Sir,

I am directed by the board to transmit to you herewith, for the information of the Lightning Rod Conference, copies of reports made by Professor Faraday to this Corporation, one respecting a remarkable stroke of lightning which occurred at the Eddystone Lighthouse in January, 1853, and the other upon a similar accident experienced at the Nash Lights in August, 1852.

The case to which Admiral Sullivan directed the attention of the Conference, as stated in your letter of the 30th October last, was probably one of these two.

Should you desire any further details in connection with this subject, the Corporation desire me to assure you of the pleasure with which they will afford any information at their command.

G. J. Symons, Esq.

[We have been favoured with copies of three separate reports by Professor Faraday, and think that it is better to give them in chronological order. There is only one other point in the correspondence from the Trinity House which it seems necessary to mention, viz., that the sections of the copper rods now used are as under.—Ed.]

REPORT on the LIGHTNING RODS of LIGHTHOUSES, 1843.

Dungeness.—Dungeness Lighthouse stands about 14 feet above the sea and measures 97 feet to the top of the lantern. The tower is of brick with wood floors; the roof and frame of the lantern are of metal seated upon a stone pedestal, to which it is secured. There is no conductor to the building. The weathercock is fitted with a glass repeller, and a rod similarly fitted is attached to the two copper flues which rise by the side of the lantern.

Eddystone.—The height of the top of the lantern of the Eddystone above the sea is about 95 feet. The roof and framing of the lantern are of metal, secured through a stone plinth to the gallery of the tower by metal fastenings. A conductor of copper rod, ¾ inch diameter, is attached to the outside of the building; the rod rises 3 feet above the top of the lantern and terminates in the sea at low water; it is fixed to the tower and lantern by metal stays and fastenings and is isolated by glass ferules. To give stability to the building eight wrought iron ties are fixed in the interior of the house, extending downwards from the underside of the lantern floor through the next two stories, terminating by inserting the ends into the stone floor, the upper ends are riveted into an iron ring round the manhole in the ceiling and further secured by iron bolts passing through the stonework and communicating indirectly with the metal work of the lantern.

Spurn Point High Light.—The Spurn High Light stands about 16 feet above the level of the sea, and measures 100 feet to the top of the lantern. The tower is of brick with wood floors; the roof and framing of the lantern are of metal, seated upon a stone plinth to which it is secured; the weathercock is surmounted by a glass repeller. An isolated conductor of copper rod, ¾ inch diameter, is attached to the outside of the tower rising some feet above the lantern and passing down the side of the tower below the surface of the ground.

South Foreland.—The South Foreland High Light stands above 300 feet above the sea, and measures from the ground to the top of the lantern 67 feet. The tower is of brick, the lantern roof and framing are of metal with a cast iron pedestal; the weathercock is fitted with a glass repeller. A conductor of copper rod, ¾ inch diameter, is attached to the outside of the tower, of the same height as the weathercock. The rod is fastened to the lantern and tower with metal stays and fastenings, and passes into the ground, turning off at right angles to the tower a little below the surface. A copper flue connected with a stove in the base of the tower, passes up the centre of the tower through the roof of the lantern, to the lower end of which a copper rod has been attached, which is carried to the outside of the building into the ground.

The undersigned have, according to their instructions, met and considered the circumstances under which lighthouses are placed as respects lightning, and have arrived at the following conclusions:—

That lighthouses should be well defended from the top to the bottom.

That as respects the top, the metal of the lantern, and upwards, is sufficient to meet every need, and satisfy every desire and fear.

That for the rest of the course down the tower, a copper rod ¾ of an inch in diameter is quite, and more than, sufficient.

That at the bottom, where the rod enters the earth, it is desirable at its termination to connect it metallically with a sheet of copper 3 or 4 feet long by 2 feet or more wide; the latter to be buried in the earth, so as to give extensive contact with it.

That glass repellers are in every case useless.

That glass thimbles are not needed, but do no harm.

That if the repeller be removed, and the point on the vane be terminated as the lightning rods usually are, and then the metal of the lantern be strongly attached to, and connected with, the upper end of the copper rod, and the rod continued down the tower to the earth, and the sheet of copper buried in it, such a system will be an effectual and perfectly safe lightning conductor.

That then there need be no rod end rising by the side of, and above the lantern.

That the rod may (if required on other accounts) come down on the inside of the building, or in a groove in the wall; but should not be unnecessarily removed from observation and inspection.

That all large metallic arrangements in the stonework, or other non-metallic parts of the tower of the lighthouse, such as tying bars, metal flues, &c., should be well connected, by copper, with the conductor.

That the vicinity of two metallic masses without contact, or metallic communication, is to be avoided.

That, as to the South Foreland High Light, the lantern, the central stove, and the copper rod proceeding from it to the earth, connected as they now are, form a perfect lightning conductor, even without the rod that is there erected; but

That it is important casual arrangements should never be depended upon for lightning conductors; but a copper rod be established for the especial purpose: for, if the former be trusted to, the carelessness or ignorance of workmen may, at after periods, upon occasions of repair or cleansing, cause the necessary metallic connection to be left imperfect or incomplete, and then the arrangement is not merely useless but dangerous.

That, as to the Eddystone, it is desirable to connect the system of wrought iron ties in it with the lightning conductor, by joining the lower part of that iron rod which is nearest to the conductor with the latter, by a copper rod or strap, equivalent to the conductor in sectional area.

That the Dungeness Lighthouse is in a very anomalous condition; to rectify which the two repellers should be removed, and also the representative of the top of a lightning rod attached to the flue, and that then a good copper conductor should be attached to the metal of the lantern, upon the principles already expressed.

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The reference, on the important subject of lightning conductors, is to Mr. Faraday and to me. On receiving it I prepared drawings of the buildings to which our immediate attention was required, with an explanation of their present conductors.

These were considered at a meeting with Mr. Faraday, when he explained the principles and their application to the several cases, deduced from his copious experiments and scientific observations.

I have since received from him the accompanying Report for my signature along with his, but the report is altogether Mr. Faraday’s and therefore I prefer adding my approval of all it contains in this separate sheet, and recommending that authority be given to me to act upon it.

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I fortunately reached the Nash Low Lighthouse last Thursday, before any repairs were made of the injury caused by the discharge of lightning there, and found everything as it had been left: the repairs were to be commenced on the morrow.

The night of Monday, 30th August, was exceedingly stormy, with thunder and lightning; the discharge upon the lighthouse was at six o’clock in the morning of the 31st, just after the keeper had gone to bed. At the same time, or at least in the same storm, the flag-staff between the upper and lower lights was struck, and some corn stacks were struck and fired in the neighbourhood. It is manifest that the discharge upon the tower was exceedingly powerful, but the lightning conductor has done duty well—has, I have no doubt, saved the building; and the injury is comparatively slight, and is referable almost entirely to circumstances which are guarded against in the report made by myself and Mr. Walker 22nd September, 1843.

The conductor is made fast to the metal of the lantern, descends on the inside of the tower to the level of the ground, and passes through the wall and under the flag pavement which surrounds the tower. It is undisturbed everywhere, but there are signs of oxidation on the metal and the wall at a place where two lengths of copper are rivetted together, which show how great an amount of electricity it has carried.

A water-butt stands in the gallery outside the lantern. A small copper pipe, 1 inch in diameter, brings the water from the roof of the lantern into this butt; it does not reach it, but terminates 10 or 12 inches above it. A similar copper pipe conducts the surplus water from the butt to the ground, but it is not connected metallically with the other pipe, or with the metal of the conductor, or the lantern. Hence a part of the lightning which has fallen upon the lantern has passed as a flash, or, as we express it, by disruptive discharge from the outside of the lantern to this tub of water, throwing off a portion of the cement at the place, and has used this pipe as a lightning conductor in the rest of its course to the ground. The pipe has holes made in it in three places, but these are at the three joints, where, it being in different lengths, it is put together with tow and white lead, and where of course the metallic contact is again absent; and thus the injury there (which is very small) is accounted for. The pipe ends below at the level of the ground in a small drain, and at this end a disruptive discharge has (naturally) occurred, which has blown up a little of the cement that covered the place. Some earth is thrown up at the outer edge of the pavement round the tower over the same small drain, which tends to show how intense the discharge must have been over the whole of the place.

Inside of the lantern there are traces of the lightning, occurring at places where pieces of metal came near together but did not touch, thus at the platform where a covering copper plate came near to the top of the stair railing, but the effects are very slight. All the lamps, ventilating tubes, &c., remained perfectly undisturbed, and there was no trace of injury or effect where the conductor and the lantern were united.

Inside of the tower and the rooms through which the conductor passes there were and are no signs of anything (except at the rivetting above mentioned) until we reach the kitchen or living-room which is on a level with the ground, and here the chair was broken and the carpet and oil-cloth fired and torn. To understand this, it must be known that the separation between this room and the oil-cellar beneath is made by masonry consisting of large stones, the vertical joints of which are leaded throughout, so that the lead appears as a network upon the surface, both of the kitchen floor above, and the roof of the oil cellar beneath, varying in thickness in different places up to ? or more of an inch, as in a piece that was thrown out. The nearest part of this lead to the conductor is about 9 inches or a little more distant, and it was here that the skirting was thrown off, and the chair broken; here also that the fender was upset and the little cupboard against the skirting emptied of its articles. If this lead had been connected metallically with the conductor, these effects would not have happened.

The electricity which in its tendency to pass to the earth took this course, naturally appeared in the oil-cellar beneath, and though the greater portion of it was dissipated through the building itself, yet a part appeared in its effects to have been directed by the oil cans, for though they were not at all injured or disturbed, the wash or colour in the wall above four or five of them was disturbed, showing that slight disruptive connections or sparks had occurred there.

At the time of the shock, rain was descending in floods, and the side of the tower and the pavement was covered with a coat of water. This being a good conductor of electricity has shown its effects in connection with the intense force of the discharge. A part of the electricity leaving the conductor at the edge of the pavement and the tower, broke up the cement there, in its way to the water on the surface, which for the time acted to it as the sheet of copper—which I conclude is at the end of the conductor—does, i.e., as a final discharge to the earth. Also on different parts of the external surface of the tower near the ground, portions of cement, the size of half a hand, have been thrown off by the disruptive discharges from the body of the tower to this coat of water: all testifying to the intensity of the shock.

I should state that the keeper says he was thrown out of bed by the shock. However, no trace of lightning appears in the bedroom, still there are evidences that powerful discharges passing at a distance, and on the other side of thick walls may affect bodies and living systems, especially by spasmodic action, and something of the kind may have occurred here. It may be as well for me to state that the upper floors are leaded together like that of the kitchen. The reason why they did not produce like effect is evident in that they from their position could not serve as conductors to the earth as the lower course could.

The keeper said he had told the coppersmith to make the necessary repairs in the pipe, and I instructed him to connect the waste pipe and the upper pipe by a flat strap of copper plate. I would recommend that the lead of the lower floor be connected metallically with the conductor to a plate of copper in the earth. I could not see the end of the present conductor, not being able by any tools at the lighthouse to raise the stonework, but I left instructions with the keeper to have it done, and report to me the state of matters.

EDDYSTONE LIGHT.—REPORT of Professor Faraday on Electrical Phenomenon which occurred thereat on the 11th January, 1853.

In reference to the remarkable stroke of lightning which occurred at the Eddystone Lighthouse, at midday on 11th January of this year, and made itself manifest by a partial flash discharge in the living rooms, I have to call your attention to the drawing herewith returned, and to the circumstances which appear (from it) to have accompanied and conduced to the discharge.

In the body of the stone work above the store-room exist eight rings of metal; each going round the building, and each being four inches square of solid iron and lead. Also, latterly the bedroom and sitting-room have been lined with a framework of iron bars, situated vertically, and pinned by long bolts into the stonework.

The part of the tower above the floor of the living-room is, therefore, filled with a metallic system, which, with the metal lantern, gives a very marked character to the upper half of the structure.

The recent metallic arrangements (but not the rings) are connected with the lightning rod; and the copper part of this rod, beginning at the floor of the living-room, then proceeds downwards by the course which can be followed in the drawing, and terminates on the outside of the rock between high and low water marks.

Considering all these circumstances, I was led to conclude that the conductor was in a very imperfect condition at the time of low water; and I had little doubt that I should find that the discharge had taken place when it was in this state, and very probably with a spring tide.

The day of the stroke was the 11th January—a new moon occurred on the 9th, so that it was at a time of spring tide.

The occurrence took place at midday; and, according to the tide tables, that was close upon the time of low water at Devonport. The end of the conductor would then be 6 feet from the water, if the latter were quiescent, and I cannot doubt that this circumstance gave rise to that diverted discharge which became so manifest to the keepers. Mr. Burges, with whom I have conversed about the matter, thinks it probable that, through the violence of the waves, the conductor does not now descend so much as is represented in the drawing.

I think it essential that the lower end of the conductor be made more perfect in its action; and I should prefer this being done on the outside of the tower and rock, if the rod can be rendered permanent in such a situation.

If it be impossible to prolong and fix the lower end of the conductor where it now is, so that it shall have large contact with the sea at low water, then I would suggest, whether or no, on the more sloping part of the rock, about midway between high and low water, three or four holes could not be sunk to the depth of 3 feet, and about 3 or 4 feet apart, and that copper rods being placed in these, they should be connected together, and the lightning rod continued to them.

If this cannot be done, then it might be right to consider the propriety of the making a hole through the centre of the building and rock, about 2 or more inches in diameter, and 30 feet deep, and continuing the conductor to the bottom.

A conversation with Mr. Burges regarding the present state of the Bishop’s Rock Lighthouse, now in course of construction, induces me also to suggest the propriety of making provision for the lightning conductor as the work proceeds.

It would be easy now to fix terminal rods of copper, and to combine them upwards with the work. Considering the isolated and peculiarly exposed condition of a lighthouse on this site, I would propose that there be two conducting rods from the lantern, down the outside on opposite sides of the tower, each terminating below in two or three prolongations, entering as proposed into the rock, or into fissures below low water mark, so as to be well and permanently fixed.

[The present Eddystone Lighthouse, that is the stone one erected in 1757–59 from Smeaton’s designs, has a total height from low water level to the top of the vane of 107 feet. The annexed engraving shows two conductors, the old and defective one passing down the left hand side and terminating half way between high and low water level, and the proposed new one on the right terminating in holes in the rock.—Ed.]

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[The following letter would have been placed in Appendix A. along with the replies from British Manufacturers of Lightning Conductors; but it did not arrive until long after they had been printed off.—Ed.]

Please find enclosed answer to your questions. In addition to manufacturing rods, we have been protecting buildings with these rods for thirty years. We sell in this way at retail from five to six hundred thousand feet each year. We also issue a guarantee of $500 (£100) on each building that we protect, which we hold ourselves ready to make good in case of failure. Now, in this extensive business, we have only had to pay one dollar damage done by lightning. We regard this as a practical demonstration that our method of protecting buildings with iron rods is as near perfect as it can be. There is more profit to be made out of the copper rod, as it is made cheaply out of sheet copper, and can be sold much higher than the iron rod. But knowing that iron for all practical purposes is the best material for lightning rods, we feel it to be our duty to do all we can to introduce it. We would most respectfully ask the Conference to investigate this question as to what kind of metal is best for rods for practical use, iron or copper. Our own late Professor Joseph Henry pronounced in favour of iron. We have many facts in relation to buildings being struck by lightning which we could give at some future time if desired. We have gathered up a large number of points that have been melted by lightning strokes. They are melted down about ½ inch. They all look as if the same amount of heat had been applied to each, showing very clearly that the quantity of electricity in lightning strokes is quite uniform. We have never in any instance known of the rod being melted, showing that the rod which we use is of sufficient size.

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1 & 2. We make spiral twisted iron rods weighing 45 lbs. to the hundred feet [7¼ oz. per foot]. The rod is of the same sized material throughout its length, except that a copper point, plated with silver and tipped with platinum, is screwed on the upper terminal.

3. No proportion is observed between the length and sectional area.

4. Joints are made by means of copper nuts.

5. Attached to building by means of zinc strips, or a casting that fits closely to the rod, which is screwed down.

6. The rod extends from 9 to 10 feet in the ground.

7. A circle twice the diameter of height of rod above roof.

8. All terminals on the roof are connected. There are never less than two ground rods, and these are increased as the number of upper terminals are increased.

We also manufacture copper rods, but do not use them where we protect buildings, nor do we recommend them to other dealers from the fact that our experience of thirty years has demonstrated that iron is the best material for lightning rods.

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A colliery chimney near Sunderland, 180 feet high, was struck by Lightning, November 13th, 1878, and I was sent for to repair it. Upon getting to the top, which was about 15 feet diameter, I found a great many of the bricks displaced, and the upper terminal of the conductor (which was a tube 0·50 in. internal, and about 0·62 in. external diameter, and which had stood about 1 foot above the top of the chimney) had been fused and was lying on the top of the chimney, it was quite brittle, and easily broken by the hand. The upper 10 feet of ½ inch wire rope was in a similar state; it seemed as if it had been passed through an exceedingly hot furnace, and I rubbed it to dust in my hands. This 10 feet length was above the first holdfast, below the holdfast the wire rope was perfectly good. The holdfast was one of those which are driven into a wooden plug let into the wall and pinned tightly down on the rope, which had been badly bruised in the fixing—in fact, knocked almost flat. I believe that this was the cause of the accident, and that the lightning travelled down as far as this holdfast, and there meeting obstruction, returned destroying the wire and rod and shattering the brickwork. The earth connection was good, the end was buried in a trench 2 feet deep and 15 feet long.

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I have been in communication with several of the principal brick builders here by whom the great majority of the chimney stalks in Glasgow and the west of Scotland are erected, and I believe the following statements may be taken as correct:—

(1) Very few stalks under ninety feet in height have lightning conductors, but, as a rule, the higher stalks have conductors. One of my correspondents says that “this rule holds good in four cases out of five.”

(2) A chimney being struck by lightning is an extremely rare occurrence in this district. One builder of long experience (Mr. McDonald) says, “I have known of several stalks that were struck by lightning, that had no conductors. I cannot point to one that was struck by lightning and had a conductor.” Another firm of old standing (Allan and Mann) say—“In our experience we have not known of a chimney stalk, with lightning conductor fixed, damaged by lightning.” Another firm (Bell, Hornsby and Co.) say—“In our experience we have not known an ordinary stalk with or without a conductor struck by lightning,” and Mr. Goldie says—“During the last twenty years I can remember only one such case,” and he is not sure whether the stalk had a conductor or not. There are three cases known to have occurred in Glasgow, but I never heard of any others among the hundreds—I may say thousands—of chimneys which are here. The great stalk at St. Rollox was struck shortly after its erection. A stalk at the works of Messrs. Alexander Paul and Co., was struck about nine years ago. Mr. Goldie makes the remark—and I think it is well worthy of notice—that in all these cases the accident happened shortly after the completion of the stalk. In these circumstances the stalk would still, no doubt, contain a large amount of moisture.

I think the St. Rollox stalk had a conductor fixed before it was struck, but I am not aware whether either of the others had.

Mr. Higginbotham (Todd and Higginbotham) tells me that the stalk at their works was struck before it was quite completed. It was very slightly injured. It was afterwards struck as mentioned in my letter. On that occasion it had a lightning conductor.

The damage done was not very serious, but necessitated the binding of the stalk with numerous iron hoops—as thus strengthened it still stands. Mr. Higginbotham says that the opinion at the time was that the conductor saved the stalk from complete destruction, but that it was too small.

They, therefore, had it replaced by a much heavier one—copper rope ?th of an inch diameter, kept 1½ inches from the brickwork by glass insulators—which still remains.

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There was no lightning conductor of any kind at Wells Church. The electric fluid struck the east side of the Tower just above the ridge of the nave roof. The tower stands, or stood, at the west end. I enclose an account of the fire from a local paper:—

Wells.—Total Destruction of the Church.—“Near midnight of Saturday last, August 2nd, 1879, a terrific thunderstorm burst over this town and a large district around, causing most intense alarm and unfortunately ending in sad disaster. The storm raged throughout the night, and was accompanied in many places by a perfect deluge of rain. Between three and four a.m. of Sunday, the 3rd, it appeared to reach its height, the lightning being of a most vivid and alarming nature, and the thunder reverberating in continuous peals. A lull then occurred, but between five and six a.m. the storm again burst out with great fury, and at 5.50 the electric fluid struck the church on the eastern face of the tower immediately above the apex of the roof, driving out a large portion of the stone work, the flints flying hundreds of feet around. One large stone fell upon the roof of a house, near the east window, and penetrated to the room below, which was fortunately unoccupied; but the tenant, Mr. R. Wharf, who slept in the next room, was aroused, and one or two persons in the road seeing what had occurred, and observing smoke directly after issuing from the roof of the church, raised an alarm of fire, which quickly awakened the whole town.

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The first visible injury to Wells Church was the “skinning” of a portion of the tower (about 10 feet high by 5 feet broad) extending downwards from the east window of the tower (i.e., the window which looked over the roof of the nave,) to the point at which the lead-covered nave joined the tower. The lightning is believed to have set fire to the roof at this point, and also to have travelled along the lead roof to the chancel, and in crossing the vestry to have ignited the surplices, as the church was seen to be on fire at both ends before the middle was touched. The “skinning” was accompanied by great disruptive force, as the stones from the tower were not only shot the full length of the church, but one large one fell on the roof of a house 60 feet beyond the east end of the church.

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As your questions in the Times of to-day allude only to protection to buildings from lightning, I need not say anything on the perfect protection afforded to Her Majesty’s ships by the conductors of Sir Snow Harris, from the time they were used in every ship in the service.

H.M.S. “Beagle,” Commander FitzRoy, was one of the first ships fitted with them. At Monte Video a heavy shock of lightning passed down the mainmast and through the ship without doing the slightest injury; but as the vane staff which tapered to a fine point, was fused at the point, it enables me to answer one of your questions. The copper was melted till the diameter was about one eighth of an inch, but below that point the conductor was not injured in any way.

You will like to know a case in which a copper wire acted as a perfect conductor, though fused throughout its length. It was at Monte Video, in the house of the English Consul, a flag-staff was struck, and conducted the lightning through a flat roof, near the bell wire of a suite of rooms (the wire ran in sight near the cornice) through a hole in each dividing wall, and then down to the bell in the basement; the wire was melted into drops like shot, which burnt a row of small holes in the carpet of each room. A dark mark, on the cornice above, showed where the wire had been. At the bell there was a slight explosion, and some little damage, but I do not recollect whether anything acted partially as a conductor from that point, and so carried off that part of the charge.

This, I think, shows that even an ordinary bell wire will act as a conductor for a rather strong stroke of lightning, as the large flag-staff was shattered.

I am anxious to call the attention of your conference to a point that it will be interesting to clear up. That is, whether a conductor should be a solid rod, or in a shape to give the largest amount of surface in the section? When I tell you that Faraday and Harris each told me that the other “knew nothing about it,” because they differed entirely on this point, I think you will see the importance of it. I had at the time to approve of the conductors for lighthouses. I will, if you wish it, give you more particulars on this point, as I believe it has never yet been settled: lighthouses having been fitted with Faraday’s, and ships and public buildings with Harris’ conductors. The one being a solid bolt, the other a hollow tube or double thin plates.

If Harris was right there is an unnecessary amount of copper in Faraday’s solid conductors; if Faraday is right, there is an unnecessary outlay in putting a given amount of copper into the shape of a tube, instead of using it as a solid rod.

P.S.—You should get from the Trinity House particulars of a case in which, with a good solid conductor, the iron floor of a lighthouse, aided by some lead in the wall, diverted the lightning from the conductor, and caused damage inside. I think it was a Portland lighthouse, but it is so many years since that I may not be right.

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Three or four years since, I was looking out of my office window in Finsbury, when a flash of lightning struck the tower of the church of St. Giles’, Cripplegate, towards which my sight happened at the time to be directed. As a portion only of the flag-staff, placed at one corner of the tower, was destroyed, I obtained permission to ascend the tower and discover the reason. I found a substantial copper rope conductor fixed in a somewhat careless fashion to the back of the tower, and passing some distance into the earth. This copper rope was about an inch in diameter, and was carried upwards, under and over several projections and cornices, and across the roof of the tower to its centre—where it stood erect, and evidently did its assigned work admirably. Clumsy and unsatisfactory as the fixing of this bent copper rope seemed to me to be, it is quite certain that it was most efficient; and had it not been for the flag-staff, capped with lead, which was carried up considerably higher than the copper rope, no evidence whatever of the lightning’s path would have been revealed. As it was, the discharge of lightning struck the leaden cap of the flag-staff, and descended down the wet, wooden pole, until the summit of the copper-rope conductor in the centre of the tower was reached, when the discharge flew across to the metallic earth conductor, leaving the lower part of the flag-staff unhurt, but shattering to splinters that portion which was higher than the summit of the copper rope.

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A small public-house of mine (the “Wheatsheaf”) stands at Trolley Bottom, in the parish of Flamstead, between St. Albans and Dunstable. On Wednesday, August 6th, 1879, about 2 p.m., during a storm, not otherwise very severe, my tenant was seated by the tap-room window (A on the plan) his wife being seated opposite to him, and having the window on her left, whilst she held her child with her right hand; there were at the same time in the room about five men besides. A sharp flash of lightning occurred, and the poor woman (when the smoke cleared away) was observed to have fallen backwards. She gasped twice, never spoke, and died immediately, and bore no further mark of injury, I understand, than a slight mark as of scorching on her neck, below the left ear. I fail to recollect whether her clothing was scorched or not, the child’s shoe and sock were both burnt, but she, herself, was unharmed. All present were sensible of an atmosphere heavily laden with sulphurous fumes; but, excepting as above, were absolutely unhurt.

On visiting the house about a week afterwards, with a view to its repair, I found a small round hole as if made with a bullet in a pane of the window (A) close to which the woman was sitting, but could discover no further injury either to the other panes, the window-frame, the floor, or anything in the room. In the parlour, B, the window-frame was violently wrenched outwards two or three inches, several of the panes were broken, one sash-line being scorched, as also the frame and linings in places, especially in the neighbourhood of the sash-weights (iron). The wooden chimney-piece E, was slightly moved from its position, the various articles upon it were scattered, and a bottle of ink which stood there, was thrown with some violence to the ceiling. The upper part of the chimney to that room, G, and a portion of the wall, of which it was a part, forming the gable end to the house were shattered, and at H a stout post, contiguous to the house wall, and supporting the roof of a lean-to, was split and wrenched from its position. The windows and frames upstairs, C D, were in the same state as that at B. The chimney, K, to the tap-room, was quite uninjured, and no harm was done to any part of the back of the house.

Flamstead is about four miles from Luton, and six from St. Albans, and stands on high land. Trolley Bottom is a hamlet half-a-mile distant, and is, as its name implies, low-lying. My house is, perhaps, the lowest in position there. It faces the North-West.

I fear that my experiences will be found to have but little bearing upon the main point you have in view, viz., the comparative merits of different descriptions of Lightning Conductors. I venture to think, however, that they are not altogether without interest as illustrating the effects of lightning in a by no means exposed situation.

I am writing only from memory what was told me at the time, and should you desire further information on any points, shall be happy to endeavour to obtain it for you.

It would interest me very much to know how it is to be accounted for that, whilst in the room in which the poor woman was struck, no further damage was done, other parts of the house were, comparatively speaking, wrecked.

I was in a house at Cannes (France) belonging to my late father on the occasion of its being struck by lightning about five or six years ago.

The storm in which it occurred was a very short one, consisting of only four explosions, every one of which took effect on some building in Cannes.

The rain was falling in torrents, and to this I consider we owed our safety as the shoots and stack-pipes being full of water acted as conductors. The villa stood high, but another building very much higher, and on higher ground, was within 100 yards. The lightning struck the metal cowl of a brick chimney, which, being an addition, was led down outside the walls of the house.

In the explosion the front of the grate of the room to which this chimney belonged, together with fire-irons, &c., were all projected across the room (a large one), about 30 feet; but no marks of lightning having entered the room were apparent. In fact the lightning after blowing up this chimney, together with much of the roof and wall of the house (great portions of the solid masonry of which I found 50 and 60 yards off!) appears to have left the chimney and, taking the course of the iron shoot round the house, to have divided into three streams, each of which ultimately found its way down a separate stack-pipe, melting in its way all the soldering of the joints, but otherwise leaving them uninjured.

One stream passed thus into a well, the door of which (locked the night before) was burst open, I presume by the sudden expansion of the air, another stream of the electric fluid passed into an underground drain, which it burst up, hurling into the air the trees planted above it, the third passing across a level asphalt roof, which it melted in spite of the water lying on it, descended into the earth harmlessly.

You will see by this that the amount of electric fluid must have been very great to require all these modes of dispersion, and it suggests the question whether the diameter of the ordinary conductors would be sufficient to carry off so great a stream. Of course, in this case, there was no conductor, and therefore no means of testing it.

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Thank you very much for the Pamphlet, which I have read with great interest. Messrs. W. & W. (page 6) state that conductors in masts (like Harris’s) are “most objectionable.” The best answer to that is: that while ships were struck in the Navy, and lives lost every year before they were introduced, no ship fitted with them ever received the slightest damage; and since all ships were ordered to be fitted—now about 30 to 35 years—I have never heard of the slightest damage, or the loss of one life—that fact upsets all theories on the subject!

Then connections between the higher and lower masts, and especially at right angles, are objected to on the ground that at a bend the conductor may be fused; such a thing was never heard of in the thousands of conductors that must have been fitted in the navy. Even if the movable plate were turned back the lightning following the longest conductor would leave one mast for the other, as the conductor went right over the mastheads, and the two conductors nearly touched each other.

At Spring Grove, near Isleworth, the church had a high spire which was fitted with a conductor, but the Vicarage was struck and some damage done to it, though, I think, much nearer to the tower than its height. I believe many are contented with one or two conductors to a building that should have many more. My small house here is about 70 feet long by 38 feet wide, and I have seven conductors—one to each chimney.

If it is once decided beyond dispute, that copper conducts in proportion to its volume; then a rod, or flat-plate, of about the proportions of one to four or five, for the purpose of fitting closer round projections, would be the cheapest and simplest form; but if it conducts in proportion to surface then of course a tube, double plate, or wire rope, would give the greatest protection at a given cost.

I firmly believe in the surface theory of Harris. I had been with him often when he made experiments nearly fifty years since, and witnessed a strip of tin foil of the thinnest kind, and about ¼ inch wide, protect a model mast of about six inches in diameter from electric shock, that without it split the mast to pieces, aided by a small hole through its centre filled with gunpowder. And I always thought that the surface-conducting theory of Harris was indisputable. But about 20 years since, having to approve a proposal of the Trinity House for a new conductor of a Lighthouse, which, like previous ones, was an inch in diameter copper rod called “Faraday’s Plan,” I thought I would go up to the Royal Institution and ask him why he did not use a copper tube instead, giving much greater conducting power with less copper. I did so, and he asserted positively that the conducting power depended entirely on the volume of copper in the section of the conductor, no matter whether it was in a bolt, plates, or tube; and that if Harris said differently, “He knows nothing whatever about it;” of course, I approved the rod conductor. But singularly enough, though I had not seen Harris for years, he came to town a few days after, and came to the Board of Trade to see me, and bring me a piece of his large tube conductor, with a connection, that he was fitting to the Houses of Parliament. When I told him what Faraday’s opinion was, he answered, “Then he knows nothing about it.” I was still inclined to believe in Harris; but a few years after, a young Indian R.E. Officer—Lieut.-Col. Stewart—whose death not long after was a serious loss to the service, was sent home to procure the electric cables for connecting different Indian ports. I was asked by the Secretary of the Indian Office to give him all the help I could. One day he came to me with a piece of the cable he proposed using. Inside the iron wires was a single stout copper wire about ? of an inch in diameter. I asked him why he had not the central wire of several strands as usual, as I believed it would greatly increase the conductive power. He said that he had carried out a number of experiments on this point before deciding; and that he was satisfied the conducting power depended on the amount of copper in the conductor, and consequently a solid wire was better than one of the same size made up by twisting small wires together.

This of course shook my confidence in Harris’ theory; but it is a point that can be easily decided by experiments on a larger scale; and I hope your Committee will be able to decide it finally.

Messrs. W. & W. prefer to a conductor on the masts a wire rope carried down from the truck, stopped to a back stay. The following fact will show its danger:—A French frigate, some fifty years since, had one so fitted as an experiment; while striking T.G. masts the conductor formed a large bight as the mast was lowered; a man standing on cap or cross-trees—I forget which—formed a shorter conductor between two parts of the wire rope and was killed without any other damage being done.

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With reference to your recent letter in the “Times,” I shall be glad if you will inform me whether there has come under the consideration of the Conference the question of lightning conductors on board iron ships with iron masts; for my part they would seem to be useless, and that if the iron mast have sufficient metallic communication, through the bottom, with the outside of the ship either by means of the screw shaft or in some other way; no additional conductor, copper ribbon, or strip, down the masts and along the decks over the ship’s side, or copper tube down the shrouds and over the ship’s side could be of the slightest benefit.

In some ships one or other of these arrangements has been adopted, and in others both have been applied at same time.

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I have observed your letter in “The Architect” of Saturday last. With reference to the subject on which it treats, I chance to have noticed since my residence here (a period of eight years) what I suppose to be an unusual frequency of lightning striking objects immediately round this spot, and the neighbourhood generally.

This inference is suggested by the fact that within the period mentioned lightning has fallen within fifty yards of the same spot three times—that this summer (one of those occasions) two other houses, both (say) within 500 yards in a direct line from this spot, were also struck—and generally, I believe, more objects are struck in this neighbourhood than usually happens to be the case.

My idea may be a fallacy, for I have no sort of statistics by which to test it; but if you suppose it is not so, and if such points come within the scope of your inquiry, I should be glad to send you a map marked with the spots where, and the dates when, lightning has fallen in or near this town. The only local peculiarities I notice are: 1. An unusual number of houses close to this have lightning conductors (a mere coincidence, and not placed there on any impression like my own). 2. We are at the bottom of a deep bay of parabolic plan which may influence the movements of electrical disturbance. 3. A soil of sand and gravel containing much oxide of iron.

[Mr. Baldry kindly supplied the map, and we find that a half circle of half a mile radius struck from the cliff-edge half a mile west of Bournemouth Pier includes the churches of St. Peter, with one conductor, and Holy Trinity with three; eight private houses with conductors, of which four houses have one each, and the other four have two, five, six and seven respectively, and within this area six objects are known to have been struck—three in the year 1879, two in 1871, and one in 1870. We do not know of any English locality where there are so many houses with conductors; but there are many more remarkable cases of repeated injury within small areas—e.g., in one storm in June, 1878, there were at least eight separate buildings injured within a circle of half a mile radius struck from the Metropolitan Cattle Market in the north of London.—Ed.]

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It occurs to me that it is worth while for the delegates of the Royal Institute of British Architects to raise the question, and, if possible settle, whether or not the gas pipes which permeate many buildings might or might not be utilized as lightning conductors; and whether any risk of gas explosion would be incurred thereby.

In my own practice there occurred the case of a lofty building, with a domed roof, and a sun-burner with a 1½ inch gas-pipe to supply it, rising to the summit of the dome, and a large iron cowl over the sun-burner.

The same circumstance occurs in most modern theatres. If the cowl were struck by lightning there was perfect metallic connection thence to the street gas mains—and one of larger sectional and superficial area than an ordinary lightning conductor would give.

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Lightning conductors have been a great hobby with me for many years, and I have induced a great number of clergymen and others to fix them to their towers and houses. During my time in the navy and merchant service I witnessed many fearful effects of lightning, and for the last thirty years I have been striving to persuade my friends to secure their houses from these terrific visitations. On the 24th December, 1699, the upper half of the fine steeple of this town was hurled to the ground, and a large portion of the church broken in. Pinnacles were then substituted for the upper portion of the steeple, to which I have had an efficient conductor attached. As far as I can gather from records, and from the abortions so frequently substituted for the original pinnacles of towers, I have come to the conclusion that nearly every tower in this country has been struck by lightning during the last 400 years, when nearly all the towers were built. Many years since, the Illustrated News gave a sketch of a beautiful steeple (in Norfolk, I believe) destroyed by lightning. It was stated that this was the second steeple which had met with so sad a fate. After the destruction of the first, a second steeple was built by subscription, at a cost of £1,000, and the scaffolding had been removed only ten days when, during a terrific thunderstorm, this second steeple was entirely destroyed! I wrote immediately to the incumbent to ask about the conductor, and his answer was that none had been fixed, but that it was quite decided that an efficient one should be attached to the third steeple! This would almost appear incredible, and I regret that I did not dot down the name of the Parish and other data, but I think it was about 20 years since.

The conductors I recommend are simply copper rods of ¼ inch diameter, attached to the highest chimney, and brought to the ground two or three feet under the surface. When buildings are longer than they are high, I always advise a conductor at each end. I generally place the conductor four or five feet above the chimney, and bring it out from the base of the building. Where a steeple or pinnacle has a vane it is only necessary to fix the conductor to the base of the spindle. Sir W. Snow Harris recommended much heavier copper conductors, but their great expense has prevented their adoption. The old conductors in men-of-war were composed of long copper links, of which nine feet went to the lb., and these were always efficient when in place. Now of ¼ inch copper rod there are only five feet to a lb., so that I give a larger margin for security.

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I observed your notice that you required information in reference to lightning and lightning conductors. A case was brought to my attention last year which occurred in Middlesborough. I enclose you particulars of the same extracted from my report, together with a tracing shewing the elevation and plan of the chimney shaft which was struck with lightning.

Extract from a Letter from Mr. E. D. Latham, C.E., Borough Surveyor of Middlesborough, dated October 11th, 1878, with reference to the striking by lightning of the chimney in connection with the washhouse at the Middlesborough Fever Hospital at Linthorpe:—

“The chimney, which is a brick one, is about 50 feet high and 5 feet square at the base and stands at the north end of the washhouse, as shown on the accompanying sketch. The conductor, a ?th inch copper rope, is fixed on the south side of the chimney with holdfasts, no insulators, and finishes in the usual manner, about 2 feet above the top. The conductor is carried under the ground for a distance of about 9 feet from the chimney, and terminates at a depth of about 4 feet in hard, rather dry clay, the end being wrapped about three times round a common brick buried in the ground. At a distance of about 9 feet above the ground at the same side as the conductor, and only about one foot from it there is a fracture in the brickwork where the electric fluid appears to have penetrated the chimney and gone a short distance down the inside, to the flue connected with the iron disinfecting apparatus, which stands at the side of the clothes boiler, as shown on the plan. The stone work of the top of the boiler was broken and other damage done.”

Extract from the reply of Mr. Baldwin Latham, C.E., to the above communication:—

“It is no uncommon thing for buildings provided with what are called lightning conductors to be damaged by lightning, and the cause is due to the inadequacy of the conductor to carry the electric fluid, which will leave the conductor for a better or a larger conductor. Wire ropes are found to be one of the worst forms, the same amount of metal when applied in a solid rod or ribbon is far more efficient, as it offers less resistance than the strands of a rope. You say your conductor is perfect, but by examination of the drawings it will be seen that the lightning descended the conductor to a certain point. At this point the iron flue enters the shaft, but some distance from the conductor; the mass of metal located there was a better conductor than the rope, so that in leaving the rope for the better conductor, the electric fluid passed through the brickwork and caused the damage. If the boiler and flues did not join in metallic communication, damage would arise from the fluid passing from the flue to the boiler, and if the boiler were not in metallic communication with the earth, farther damage would arise when the fluid left the boiler for the earth. It is well known that electricity of high tension will leave small conductors for large ones, and the knowledge of this fact is made use of in protecting the telegraph system throughout the country. Many buildings and chimneys have been struck that have been fitted with so-called lightning conductors. A perfect system of protection against lightning consists in linking together all the conductors about the buildings. Such was the system introduced by Sir W. Snow Harris and adopted by the Government.”

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Reply of Dec. 12th, 1878, acknowledging receipt of Mr. Baldwin Latham’s Letter.

“I am directed by the Town Council to tender you their thanks for the trouble you have taken, and the valuable information you have given with reference to the lightning conductor at the Middlesborough Fever Hospital.

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At the suggestion of the Engineers of the Telegraphs in the district, the earth portion of the rope has been imbedded in a mass of coke, and a quantity of old iron has been placed at the bottom of it, to counteract the influence of the boiler and disinfecting apparatus.

I beg to report an incident which occurred on board the barque “Southern Queen,” from Pensacola, while coming up Channel on the morning of the 30th of December, 1879, the Eddystone Lighthouse bearing about north, dist. 20 miles. At 6 a.m. of the above date, saw a terrific squall rising in the W.N.W. point of the horizon, with vivid Lightning in it.

We immediately reduced sails down to lower topsails and foresail, and about 7 a.m. the squall of wind and hailstones overtook us: it blew furiously for about twenty minutes, and in the height of the squall a thunderbolt broke on the ship, shattering the main royal mast-head, thence the Lightning ran down the main royal stay to the fore topmast head, and shattering that also. Thence it ran down the chain of the fore-topsail haulyard and shattered about a fathom of the chain in bits. When the bolt struck the ship it made a report like a hundred ton gun fired off. The concussion on the ship threw every man off his feet. It filled the cabin with smoke, and also the hold: the smoke had a sulphury smell; also all the compasses in the ship were so magnetized that they were flying right round.

And on arrival into the Commercial Docks we observed that a plank on each side of the ship, in the wake of the main chains, had been blown out by the Lightning. On the port side the oakum has been blown out of the seams, and the edges of the planks shattered. Since the ship has lightened up out of the water, we have discovered that the electric fluid has passed out by a copper bolt, cut the copper sheathing in the shape of a star, and turned it back.

Any further particulars I will be most happy to supply if required.

[Two of the delegates visited the ship, but with the exception of learning from the mate that he saw “a ball of fire descend from the mizen and go over the port side” they had not been able to obtain any additional particulars. They obtained some fragments of the broken chain, a much rusted iron one, weighing however about two pounds per foot.—Ed.]

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The patterns of lightning conductors obtained from Messrs. Hart, as requested, are an improvement on the first “Spratt’s Patent” purchased by the above-named firm; the original was a mixture of copper and zinc wire, which, when it was exposed to a wet and smoky atmosphere, a galvanic action took place and soon destroyed it.

About two months ago I engaged Messrs. Davis, of Derby and Newgate Street, to test a rope of the above construction that had been fixed about ten years at No. 1, Aberdeen Terrace, Blackheath, and I was present at the time, and though we had a very powerful battery we could not get a current through any part of it, as both the copper and zinc had decayed: the copper wire is not stout enough to allow for corrosion in this climate.

St. Michael’s Church, Blackheath Park, with the needle spire, as we call it—built just fifty years ago—had a ½ inch iron rod; and as it now runs through the new vestry just built I have advised the churchwardens to have it tested, and they are going to have it done in the course of a week or so.

St. Alphege Church, Greenwich, has a ribbon of copper about 1½ inches wide by ¼ inch thick, and that has been up many years, and is as sound as when it was fixed, for I examined it about two months ago.

I have advised the owner of No. 1 Aberdeen Terrace, to have a ribbon of copper, as I am certain that wire ropes are not to be depended on in this climate.

Hoping these few remarks will not be deemed out of place,

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I have the honor to forward notes of an accident from lightning, which I lately witnessed, having been informed that your Committee desires such information.

The very rough sketch which I attach is, I believe, accurate; but I was only allowed to look in at the door while a strong light was held within, and to view the outside of the building. A native draughtsman belonging to the office, however, was allowed to make some measurements, which he communicated to me.

It seemed to me that the case was worthy of record, because the building was so little injured.

May 8th, 1878.—Camped at Pedda Kondur, a village on the west bank of the Kistna river, about 10 miles below Bezoarah anicut. All the morning there was a southerly wind blowing unsteadily; by noon it fell calm, and was very hot, clouds gathering in the east. Soon after midday thunder was heard to the east, and a storm was evidently approaching. About 3 p.m. wind began to blow from the east, and soon rose to a gale, bringing thick clouds of dust, and the thunder sounded very near. It rained rather heavily, which laid the dust, and black clouds could then be seen over-head, and nearly all round: the thunder, which was very loud, sometimes sounding quite over-head. By half-past four the rain had slackened, but thunder was almost incessant, and very loud. Just at this time a stream of lightning descended within 80 yards of the tent, and was accompanied by a tremendous explosion. The lightning struck a small pagoda near the village, and some of the natives said that they observed smoke rise from the summit when the lightning descended.

The accompanying rough sketch will show what the building is like. The main part of it is a square pyramid, each side of the square, outside measurement, being about 18 feet; height of apex above ground, 32 feet. Built on to one side of the pyramid is an entrance chamber, with flat roof, about 10 feet square, and the same in height. The apex of the pyramid is surmounted by a metal (probably copper) finial, about 1 foot in height; the ordinary attachment of such a finial to masonry is by means of a small stake built into the masonry, on which the finial—which is cast hollow—is fixed, and round which it is plastered with mortar.

The interior of the pyramid forms one room, about 10 feet square, with a domed ceiling, the thickness of the dome at crown being 2½ feet. In the centre of this room is placed the idol, in this case a lingam, or cylindrical stone pillar, 1 foot 4 inches high, and about 9 inches in diameter, which stands on a square hollow stone tray (not cut out of one stone, but fitted in two or more pieces) in which the offerings of ghee, &c. are placed. This tray has a small spout on each face to carry off the liquid ghee and water with which the priests’ ablutions are made. The tray is raised on masonry, so that the height of the top of the lingam is 3 feet 4 inches from the floor. The floor of the room is 1 foot above the surrounding ground; there is only one doorway leading from the porch or entrance room above mentioned; and the sacred edifice is closed by a substantial wooden door, with iron hinges and lock, on the outer face of the entrance chamber. The whole building is of brick in mortar, unplastered, and presents the appearance of being weather worn.

The pagoda is at a distance of about 20 yards from some low native houses, and stands in an open space, on two sides of which is the native village; round the houses are some trees, mostly of small size, but within 50 yards of the pagoda are two separate trees, which certainly exceed it in height. The village is situated on the margin of the Kistna river, and the surface of water in wells is at least 10 feet below the surface of the ground.

The lightning struck the metal finial on the top of the pagoda, and passed vertically through the dome, travelled along the east side of the lingam without leaving any mark, and bored a small round hole in the stone tray beneath it, passing into the ground below without disturbing the idol or its foundation. The hole in the tray was not quite large enough to admit the point of a little finger, and it was situated on a joint of the stone, a place where moisture would probably linger. The finial appeared undisturbed, but the masonry immediately round its base was shattered, and a shower of pieces of brick and mortar was sent from the top of the pyramid and scattered over the ground on the east side to a distance of about 20 feet from the base. The masonry of the apex of the pyramid was cracked in three places, and a small hole was bored in it, on the east side of the finial, apparently about the same size as that in the stone tray; but otherwise the masonry of the building appeared totally uninjured—not a crack could be found anywhere.

The soil at this place is a clayey loam, rather lighter than the ordinary delta alluvial soil.

When the building was struck a sulphurous smell was noticed.

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Adverting to your letter of the 13th ultimo, I have now the honour to forward herewith for the information of the Lightning Rod Conference copies of two Reports relating to the lighthouse at Berehaven being struck by lightning, in 1877, which, no doubt, is the Station alluded to by Professor Tyndall in his conversation with Mr. Inglis, of the Trinity House.

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I most respectfully beg leave to state that, in accordance with your instructions I proceeded to Berehaven Lighthouse, and on my arrival at that station I made a very careful examination and found that the lightning was conveyed into the lantern by the iron stay bars that were connected to the lightning conductor at a collar about 5 feet over the gutter on the outside of the dome for the purpose of securing it, and bolted to the dome of lantern by iron bolts. After bursting off the several coats of paint at the heads of the bolts, it put out the lights, breaking the glasses, and knocking down both light keepers insensible; it having twisted off the lead voice-tube where it was secured to the side of the lightroom by a holdfast, bursting out the stone sheeting between the iron pillars supporting the marble top; it then passed through the voice tube to the principal keeper’s bedroom, where it burst out the studding and lath and plaster, and tearing away the voice-tube, the foot-board of the bed, and destroying the pictures that were hanging on the walls. It would appear that the current was interrupted in its course by the sudden bend of the voice-tube; for, after having dealt destruction in this apartment it was attracted by the iron holdfasts and spikes that secured the voice-tube and studding to the walls, and passed out through the external walls of dwelling to the out offices, where it passed along the eave gutters to the end of them; it then followed one of the iron holdfasts, and entered the wall, destroying it, and bursting out the cut-stone kneeler and barge course, it then passed down through the roof of the low buildings, destroying the slating, passing through the walls of the pantry, &c., tearing up portions of the 3 inch Yorkshire flagging of the floor and yard, dealing destruction to the shelving, doors, door frames, brickwork, glass, &c., and bursting up the seat of principal keeper’s w.c., it passed along the sewer to the assistant keeper’s w.c., breaking up the flags and seat and then passed out through the roof. Another current was attracted by the eave gutters at the east angle of the dwelling near the tower, and passed along them to the north east angle, splitting them through the centre. At this point its course was changed to the west, and passed into the assistant keeper’s yard and down the rain water pipe to the water tank, splintering it and the slating and brick wall, &c.; it also appears that the lightning struck the south-east side of the tower and entered it in several places at the base and near the lightning conductor, and apparently glanced off it where it was secured by holdfasts to the tower, rooting up the solid rock, but giving no indication that it had been conveyed to earth by the conductor as intended: the lightning also entered the assistant keeper’s kitchen through the chimney, knocking down a portion of the brickwork, &c.

I may remark that the lightning conductor is formed by a copper rod, which stands about 10 feet over the gutter on the outside of the lantern, and is secured by three iron stays to the dome, as before described, and passes down through the centre of the gutter to the under side, where it is connected to a ½-inch copper-wire rope, which continues down the outside of the lantern close to the glass to the floor of the balcony, passing through the stone floor by means of a hole, jumped through it, then continues down the face of the tower closely pressed to it by the iron holdfasts and copper bands, which secure it until it reaches the rock at the base of the tower, where it terminates in a small hole 3 inches by 3 inches, jumped out of the rock about 6 inches under the surface.

After having made a careful survey of the damage done, I deemed it advisable, and at the solicitation of the principal keeper, who seems to have been greatly shaken and nervous, to have the iron stay-bars disconnected from the dome of the lantern and the bolt-holes plugged up with timber, fearing a recurrence of the accident, as the weather was very stormy, and should lightning come on no person on the rock would enter the lantern. I also considered it prudent to have the loose gutters and cut-stone, also a part of the gable of the out offices, taken down, as it was in danger of falling into the narrow yard, which might cause a sad accident.

Having provided workmen and materials and scaffolding for doing this work I again landed on the rock on Saturday last, with great difficulty, having been detained a day by the storm, and pointed out the temporary repairs that were necessary to be done for the protection of the people on the rock.

The probable cost of repairing the damage done the buildings, independent of the lightning conductor, and which require to be done without delay, will be £120. Hoping the action I have taken in this matter will meet with your kind approval, I have the honour to be

[The other report is to the same effect as the above, and is therefore omitted.—Ed.]

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ACCIDENT BY LIGHTNING at Upwood Gorse, Caterham, the residence of J. Tomes, Esq., F.R.S. 28 May, 1879.

As I happened to be visiting Mr. Tomes, in the autumn of 1879, I took the opportunity of obtaining all the particulars I could with reference to the accident which occurred on the night of the 28th May, 1879, when his house was struck by lightning.

The house, a sketch plan and elevation of which are annexed, stands upon a hill upwards of 700 feet above sea level, and is somewhat higher than any other object in the vicinity. It is covered by a steep tiled roof, that of the principal portion of the house being somewhat higher than the rest, and upon the ridge of this roof stand two brick chimney stacks of equal height. Upon the eastern stack, at its southern end, was fixed a lightning conductor (shown by the line, A. B. C., on the south elevation), the upper part consisting of a point and a length of copper tube ½ an inch external and ? inch internal diameter, which was screwed into a collar connected to a woven band of one zinc and thirteen copper wires carried through glass insulating rings along the slope of the roof, over the rain-water gutters and down the side of the house into the ground, going only 12 inches into dry chalk.

The electric fluid struck the lightning conductor, hurled the rod down and shattered the chimney pots and some of the brickwork. The rod was broken at the point marked A on the south elevation, where the sectional area of the copper rod was reduced by the screw being cut into it for the collar, which connected the rod with the woven band. This junction and a portion of the band are forwarded for inspection, from which it will be seen there are no rough broken surfaces, but that the thread of the screw was partly melted. The copper wires composing the band were bright and nodulated here and there throughout their length, showing that it had been heated up to a sweating temperature. The zinc wire was not continuous, having been wasted by oxidization. It showed no indication of having been hot.

Having broken the conductor, the discharge appears to have divided at the ridge of the roof, a portion passing down the southern and a portion down the northern slope of the roof. That portion which passed down the southern slope apparently followed the course of the conductor band as far as the iron rain-water gutter, which it cracked, and perforated two holes, about half an inch diameter, in two panes of glass at B. Here the current apparently again divided, as shown by the dotted line from D to E on the south elevation, some passing westwards and some eastwards along the rain-water gutter round the eaves of the house, as traced by the broken joints of the gutter. Westwards these joints (which were made of red lead) were only broken from B to D, but eastwards they were broken from B to E, and right round the eastern side of the house to F, and along the northern side as far as G.

What seemed to be the greater portion of the discharge, however, passed down the northern slope of the roof and along the course shown by the dotted lines on the Plan and north elevation. The lightning first followed the lead flashing H of the chimney stack, next broke some tiles at I, and then without disturbing any of the rest of the tiling, leapt across the roof, a distance of some 15 feet, to two galvanised iron water cisterns in the roof at K, perforating a hole through the 9–inch brick wall of the house in its course.

This hole, which was circular, was large enough to admit one’s finger easily and was blackened on its interior; when first examined, eight or ten minutes after the occurrence, it was still quite hot. One edge of the lead flashing outside the wall was fused at G, close to the rain-water gutter, from which it would seem that the current again divided at the wall of the house. There are two galvanised iron cisterns at K, connected by a pipe underneath (see adjoining sketch plan), and the discharge appears to have passed from one cistern to the other and then along the 1½ inch iron barrel rising main, from pumps, to the point L¹ in the back kitchen, where the iron pipe separated into two branches leading to the two pumps L² and M.

Probably a portion of the discharge passed down the iron suction pipe from the pump L² into the rain-water tank P, but however this may have been, a considerable portion passed from point L¹ along the 1½ inch iron pipe LM to the pump M in the scullery, and thence along a ¾ inch iron pipe to a water tap fixed over the iron sink N, but not in metallic connection with it. Here the lightning broke the slate at the back of the sink and sent it showering across the scullery, breaking the things on the opposite side of the room. The iron sink was set on brick piers and connected, by means of a 1½ inch iron pipe, with the self-acting syphon “Flush Tank” O in the yard. This “Flush Tank” consisted of a cylindrical cast-iron tank about 26 inches in diameter and 26 inches deep, buried two-thirds in the ground, so that it formed a fair earth connection.

There is an account of the accident in a letter by Mr. Charles S. Tomes in Nature, of 12 June, 1879 (which has been made use of in the present description), and there is also a letter about the accident by Mr. Newall on the next page of Nature to Mr. Tomes’ letter. The description in this latter letter is, however, erroneous in several particulars, especially where it speaks of the lightning passing round the iron gutters to the iron water cisterns.

[Note.—Mr. Tomes has most kindly sent the whole of the upper parts of the conductor; and as the accident appears a very instructive one we give full details, together with engravings of the more important portions of the conductor.—Ed.]

This conductor was of the pattern known as Spratt’s patent. The upper terminal was what the vendors call a “reproducing point,” which they say is “formed of two or more metals: the inner or core being steel, and the outer of silver alloy, tipped with platinum;” the idea of the inventor is said to have been that “should the outer coating become fused by an extraordinary charge of electricity, the core will remain intact to receive any further discharge.” In the present case the top is broken and the iron centre is rusted and bent, but there is no indication on the remaining portion of heat or fusion.

This point A was well screwed into a stout copper collar B.

Into the same collar was screwed the upper end of a copper tube C, 5 ft. 1 in. long, external diameter, 0·5 in., and internal diameter about 0·36 in., giving a thickness of only 0·07 in., or but little more than a sixteenth of an inch. The mass of copper was therefore about equal to a tape 1½ × 1/16, or ¾ × ?, or to a rod one-third of an inch in diameter—the area being as nearly as possible 0·09 in. The tube weighs 29½ ounces, which corroborates the above measurements and shows that it weighs rather less than 6 ounces per foot. This part of the conductor was evidently greatly heated, as there are distinct marks of sweating in several places. The lower part of this tube was screwed into the collar D (which is drawn of its actual size in the annexed sketch) in order to make connection with the short length of copper tube F, a portion of which is also engraved, of its actual size. It was at E that the rupture occurred. The charge passed the point A, then the top collar B, and although it greatly heated the 5 ft. copper tube C, still no damage was done, and so it passed into the second collar. Here, however, there seem to have been two faults: the short copper tube F, was very slight, weighing but little over 3½ ozs. to the foot, and this, which represents but a very slight conductor, was greatly lessened by a deeply-cut thread to the upper end, whereby the area was reduced to less than 1/20th of an inch. As this was not screwed home, the total sectional area at E immediately below the collar was reduced to the above small amount, rupture and fusion occurred, and much of the charge left the conductor. This short length of tube was, however, raised to a sweating temperature in two places.

The conductor consisted of 14 wires made into a flat plait, the wires seem to have been of the following dimensions:—

	Each of No.				Total area.
12	copper wires,	15	B.W.G., dia. of each	·072 in.:	0·048 in.
1	copper wire,	18	B.W.G., dia. of each	·049 in.:	0·001 in.
1	zinc wire,		of each	·049 in.:	0·001 in.

Thus the total sectional area of the plait G would be about 0·050 in., or rather more than that of the short copper tube into the lower end of which it was roughly thrust and riveted—but the joint was bad, there was no solder at all, and the metallic contact was very imperfect.

As to the state of this plait (which was less than an inch wide, and less than ? in. thick), and as to the ridiculously imperfect earth terminal, details are given in Mr. Field’s letter.

It may be well to recapitulate the dimensions:—

Description.	Length.	Dimensions.	Sectional Area.	Heat Effects.
“Reproducing point”	9 in.	0·45 × 0·45 in.	0·20	None visible.
Collar	1¼ in.	0·75 in. diam.	0·24	None visible.
Copper tube	5 ft. 1 in.	External 0·5 in. dia. Internal 0·36 in. dia. }	0·09	{Sweated in places.
Collar	1? in.	External 0·75 in. dia. Internal 0·50 in. dia.	0·24	None visible.
Short tube	7 in.	External 0·50 in. dia. Internal 0·375 in. dia.	0·09	{Sweated in places.
Short tube where threaded	¾ in.	External 0·438 in. dia. Internal 0·375 in. dia.	0·04	Fused.
Plait	53 ft.	? 0·7 × 0·072 in.	0·05	Sweated in places.

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We herewith hand you our circular, setting forth our ideas as to lightning conductors. We claim that if one or more sharp edges or points is so essential on the most elevated part or parts of a conductor, why not establish this principle the entire length of the conductor? or why not leave these most elevated part or parts blunt, or erect a small gilt ball?

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I think that it would be very valuable if the Conference considered how far iron ventilating pipes to drains will safely act as lightning conductors. These pipes generally consist of iron jointed with red lead or putty. Will not these joints interfere? Very often also a portion of the pipe is wholly of lead. So many of these pipes are now carried up to a very high level that the question is important.

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Our opinion is that the drain to our Powder Magazine at Bruntcliffe (see ante page 74) had no water in it at the time of the occurrence.

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We have the pleasure to send you a plated model of our new Conductor Coupling, and hope you will be pleased with it.

When screwed up, the contact between the rod and the copper tape is perfect. It is, of course, a very simple thing, but it overcomes the difficulty of soldering, which is always more or less uncertain, and rivetting up aloft is apt to be scamped.

And as to soldered connections, apart from the uncertainty of permanent contact, it is very important to keep the soldering iron away from roofs, it often damages the lead, and (as at Canterbury) the fire-pot is a source of great danger to buildings.

A is the copper tape conductor. B is a screw plug, having two slots, a a (see fig. 3), and an intervening division b, all cast in one piece. The tape or rope A is passed through one of the slots a, and bent over the division piece b, the bent portion A1 is then returned through the other slot. A screw socket forming the coupling C, bearing a collar to rest in a ring bolt built into the structure to be protected, is then screwed on to the plug B, and into this socket the rod or tube D is screwed, it being suitably tapped for its reception, until the lower end of the rod or tube is in firm contact with the tape or rope. These latter are then firmly held together, and cannot by any possibility come apart.

Note.—In fig. 2 the rod and tape are not shown in actual contact, the drawing being intended to exhibit the separate parts.

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I have the pleasure of furnishing details of the recent damage to Christ Church, at Carmarthen. The circumstances are these:

At the Eastern end of the church stands an ordinary square tower, covered with a sloping slated roof; this roof is capped by an ornamental open ironwork ridging, terminating at each end in a light open iron pinnacle, and having in the centre another pinnacle similar to those at the extremities. A is a view of this ironwork from the east end of the church.

The conductor consisted of seven copper ropes stranded together, each rope consisting of seven strands of No. 18 wire, the whole having a diameter of about ½ an inch. It was fixed to the building by ordinary copper staples; it ran up, and was attached to the southern portion of the ornamental railing, and it terminated in a single point. There was no special connection between the conductor and the iron guttering of the church.

I could not ascertain in what manner the earth was made, but it was an imperfect one, giving a resistance of 115 ohms, and this resistance would have been greater but for an accidental circumstance mentioned further on.

The lightning struck the central iron pinnacle of the ornamental ridge and broke it off. In falling to the ground it was shattered into about twenty pieces; but on the upper extremity, which was a solid cast-iron spike, about ¾ inch square, there were marks of fusion across the whole of the top to the depth of ?th of an inch.

I could not observe other marks of fusion at the point where the pinnacle was broken off, but the lightning made its way to the conductor, and on reaching the ground, at a distance of 4 feet from the point where it entered, it burst out with explosive violence, blowing a circular hole in the ground 2 feet in diameter and 8 inches deep (marked B in plan). The earth from this hole was blown into the air, and fell in a fine shower on objects standing 3 or 4 feet high and 14 or 15 feet from the hole.

A second flash struck the iron guttering at the south-western extremity of the church (C), broke off a 2 feet length, and ran down the waterspouts (D D). Opposite one of these a second hole, 9 inches deep and a foot in diameter, was blown out of the ground, some 3 feet from the base of the spout.

On examining more closely the surroundings of the lightning conductor, I observed that the church gas-pipe, an iron one, about 1¼ inches in diameter, passed through the wall of the building about 6 feet from the conductor, and was carried in a direction corresponding with the hole caused by the explosion (see plan). I immediately concluded that this explosion was due to the current breaking across from the conductor to the gas-pipe, and on opening up the hole I found this to be the fact. The conductor crossed the gas-pipe at nearly a right angle, being about a foot above it. The under portion of the conductor bore evident marks of fusion, and, more interesting still, the gas-pipe was slightly coated with a very thin deposit of copper, so thin that it perished in my attempt to remove it; but still there was an undoubted coating at one spot. But for the proximity of the conductor to the gas-pipe, the earth resistance of the former would doubtless have been greater than it was, and the damage would probably have been increased.

I was sorry that no means existed for examining the ornamental ridge, but doubtless the metallic contact between the sections was very imperfect, and to this cause was due the rupture of the pinnacle.

The fact, too, that the protector did not prevent the south-western portion of the building being struck bears on the question of the area made safe by a protector.

The tower stood 89 feet above the ground, the top of the iron pinnacle 99 feet, and the protector extended 1 foot 6 inches above the latter, thus reaching a total height of 100 feet 6 inches. The total length of the church was 123 feet.

The point C where the gutter was struck was 84 feet in a direct line from the conductor, and stood 24 feet above the ground. This gives a vertical height of the conductor of 76 feet 6 inches above the point struck, the distance of the latter being a radius 8 feet greater than the height of the former.

ACCIDENT at BOOTHAM BAR, YORK, compiled from notes and measurements taken by J. Edmund Clark.

The discharge occurred about 3 a.m., 22nd June, 1876. The principal injury occurred to the bracket lamp at A. This lamp, which was an ordinary street one, was supported by an iron bracket 2 ft. 6 in. long, and 11 ft. 6 in. above the pavement. The gas was conveyed to it by 11 ft. 6 in. of vertical iron gas barrel, and thence to the burner by about 3 ft. of ordinary ½ in. composition pipe. The glass of the lamp was not broken, but about 18 inches of the composition piping was twisted and split open as with a sharp knife, and the other 18 inches was melted; the gas was ignited and burning from the top of the iron barrel, thus producing a large flame which ignited the house to which it was fixed. That part of the lead pipe which was inside the lamp was uninjured, whence it would appear that the point struck was at or near to the top of the iron gas barrel; and this is supported by the fact that the lead over the shop window and close to the bracket was turned up off the wood-work.

The lamp, as will be seen by the plan, is attached to the corner of a house, the eaves of which were 20 ft. above the lamp, while the ridge, with a little lead flashing, was 24 ft., and the chimney pots were 31 ft. above the lamp, and not 15 ft. distant horizontally. This house was slated and had wood gutters, and an iron rain-water pipe, but the latter was 33 ft. horizontally from the point struck. The wooden gutters were very old and rotten, and one of them was very slightly shifted; it is not certain that this was done by the lightning, and there was no other indication of its presence.

C is a lamp bracket extending 4 ft. from the wall of the house, and at D are two old iron brackets.

At the distance of only 8 ft. from the lamp in the opposite direction (N.W. of the lamp) rises Bootham Bar, a massive stone structure, of which the four turrets rise to 44 ft. 3 in. above the pavement, and therefore 33 ft. above the lamp. The whole roof, about 750 square feet, is covered with thick sheet lead, and the building also contains the old portcullis B heavily shod with iron.

The noteworthy feature of the case appears to be, that the only injury is found at a spot surrounded by objects close to it, and greatly exceeding it in height; in fact, that the lightning dipped into a sort of cavity, instead of striking at the higher objects.

It is evident that in this case, although the composition pipe was melted, the iron one afforded ample conduction, and the city gas mains a perfectly safe earth terminal.