What to look for ... We may not see what we do not expect to see ... Lenses reveal worlds great and small otherwise unseen ... Observers of the heavens and of seashore life ... Collections aid discovery ... Happy accidents turned to profit ... Value of a fresh eye ... Popular beliefs may be based on truth ... An engineer taught by a bank swallow.

Ability to observe is an unfailing mark of an inventor or discoverer: it is quite as much a matter of the mind as of the eye. A botanist, keenly alive to varieties of hue, of form in leaves, tendrils, and petals may not give a second glance to stratifications which rivet the gaze of a geologist for hours together. Each sees what he knows about, what he is interested in, what he brings the power and desire to see. When Faraday was asked to witness an experiment he always said: “What is it that I am to look for?” He knew the importance of concentrating his attention on the very bull’s eye of a target.

How much goes to sound observing is thus stated by John Stuart Mill,—“The observer is not he who merely sees the thing which is before his eyes, but he who sees what parts the thing is composed of. One person, from inattention, or attending only in the wrong place, overlooks half of what he sees; another sets down much more than he sees, confounding it with what he imagines, or with what he infers; another takes note of the kind of all the circumstances, but being inexpert in estimating their degree, leaves the quantity of each vague and uncertain; another sees indeed the whole, but makes such an awkward division of it into parts, throwing into one mass things which require to be separated, and separating others which might more conveniently be considered as one, that the result is much the same, sometimes even worse than if no analysis had been attempted at all.”

How an explorer of ability may witness a new fact without realizing that it points to a great industry, is shown in the case of Lord Dundonald. In 1782, or thereabout, near Culross Abbey in Scotland, he built a tar-kiln. Noticing the inflammable nature of a vapor arising during the distillation of tar, the Earl, by way of experiment, fitted a gun-barrel to the eduction pipe leading from the condenser. On applying fire to the muzzle, a vivid light blazed forth across the waters of the Frith, distinctly visible on the opposite shore. Soon afterward the inventor visited James Watt at Handsworth, near Birmingham, and told him about the gas-lighting at the kiln, but his host paid no attention to the matter. His assistant, William Murdock, however, was impressed by the story, and some years later applied gas to the illumination of the Soho works where Watt’s engines were built. This was the beginning of gas-lighting as a practical business.

Professor Adam Sedgwick, of Cambridge University, famous as a geologist, and Charles Darwin once took an excursion in Wales amid markings of extraordinary interest which neither of them noticed. Darwin tells us: “I had a striking instance of how easy it is to overlook phenomena, however conspicuous, before they have been observed by any one. We spent many hours at Cwm Idwal, examining the rocks with extreme care, as Sedgwick was anxious to find fossils in them, but neither of us saw a trace of the wonderful glacial phenomena all around us; we did not notice the plainly scored rocks, the perched boulders, the lateral and terminal moraines, yet these phenomena are so conspicuous that, as I declared in a paper published many years afterward, a house burnt down by fire could not tell its story more plainly than did this valley. If it had been filled with a glacier, the phenomena would have been less distinct than they now are.” At a later day when Darwin’s powers of observation had become acute in the highest degree, he noticed a bird’s feet covered with dirt. Rather a common fact, not worth dwelling on, earlier observers had supposed. Not so thought Darwin. He carefully washed the bird’s feet, and planting the removed solids he was rewarded with several strange plants brought from afar by his winged visitor.

A cousin to Charles Darwin, Francis Galton, is an investigator of eminence. In a study of visual memory, a faculty in which observation bears its best fruits, he says:—

“It is a mistake to suppose that sharp sight is accompanied by clear visual memory. I have not a few instances in which the independence of the two faculties is emphatically commented upon; and I have at least one clear case where great interest in outlines and accurate apprehension of straightness, squareness, and the like, is unaccompanied by the power of visualizing.”

A new instrument, machine or engine is imagined by its creator long before it takes actual form; everything he sees that will be of help he builds at once into his design, everything else, however interesting in itself, he passes with a heedless eye.

Think Birds and You Shall See Birds.

“If we think birds, we shall see birds wherever we go,” says John Burroughs. An observer faithful and accurate in noticing birds and beasts, rocks and leaves, may come at last upon a flower which opens a sphere of knowledge wholly new, as when the round-leaved sun-dew was first observed to entrap and feed upon insects. Much, also, depends upon comparisons such as occur only to a mind at once broad and alert. One may notice in spring and early summer a few leaves growing directly from the trunk of a tree, sometimes near the ground. In maples these leaves are decidedly narrower than those growing from branches in the usual way, and they often have a reddish tinge. Comparing a variety of such leaves with fossil impressions of allied species, Professor Robert T. Jackson of Boston came upon an interesting discovery. He found that these sporadic leaves closely resemble those borne by the remote ancestors of our present trees: they are the lingering reminders of a far distant day.

An observation equally keen saved the orange groves of California from destruction by the fluted scale insect. In 1890, or thereabout, the orange growers in their extremity sought the advice of Professor C. V. Riley, entomologist to the Department of Agriculture at Washington. He asked: “Where did the pest come from?” “Australia,” was the answer. “Is it much of a nuisance there?” “Not particularly.” “Then what keeps it down, what preys upon it?” “Nothing specially,” was the response. Dissatisfied with this answer, Professor Riley sent to Australia a trained entomologist and acute observer, Mr. Albert Koebele, who gathered various insects noticed as preying upon the fluted scale. Distributing these upon his arrival in California he was fortunate enough to find that one of his assisted emigrants, a lady bird, Vedalia cardinalis, fed so ravenously upon the fluted scale as to restrict its ravages to quite moderate proportions.

It was an equally disciplined eye which in the laboratory first noticed that air is non-conducting until traversed by an X-ray, when it becomes conducting in a noteworthy degree. The field of radio-activity, at which we have glanced in this book, owes its cultivation to observers keen to note phenomena utterly unlike those before dwelt upon by the human eye. Often close observers learn what would never be imagined as possible: in rifle-making the tendency of the drills, which revolve nearly a thousand times a minute, to follow the axial line in a revolving bar is a fact which may be accounted for after observation, but which no one would predict.

One day on the Glasgow and Ardrossan Canal a spirited horse took fright; it was then observed, with astonishment, that a boat, the “Raith,” to which it was attached, for all its increased speed, went through the water with less resistance than before. The vessel rode on the summit of a wave of its own creation with this extraordinary effect. The “Raith,” said Mr. Scott Russell, “weighed 10,239 pounds, requiring a force of 112 pounds to drag it at 4.72 miles an hour; 275 pounds at 6.19 miles an hour, and but 268¹/₂ pounds at 10.48 miles per hour.” Thus paradoxically was reversed the rule that the resistance of a vessel increases rapidly as she is moved through the water. Mr. Russell added:—“Some time since a large canal in England was closed against general trade by want of water, drought having reduced the depth from 12 to 5 feet. It was then found that the motion of the light boats was more easy than before; the cause was obvious. The velocity of the wave was so much reduced by the diminished depth, that, instead of remaining behind the wave, the vessels rode on its summit.”

The Mississippi Jetties of James B. Eads.

One of the most difficult problems ever solved by an American engineer was the making navigation safe for vessels of fairly deep draft in the lower branches of the Mississippi. The difficulties were overcome by James B. Eads, of St. Louis, in his system of jetties. He remarked, says his biographer, Mr. Louis How, that other things being equal, the amount of sediment which a river can carry is in direct proportion to its velocity. When, for any reason, the current becomes slower at any special place, it drops part of its burden of sediment at that place, and when it becomes faster again it picks up more. Now, one thing that makes a river slower is an increase of its width, because then there is more frictional surface; and contrariwise, one of the things that makes it faster is a decrease of its width. Narrow the Mississippi then, at its mouth, said Eads, and it will become swifter there, and consequently will remove its soft bottom by picking up the sediment (of which it will then hold much more), and by carrying it out to the gulf, to be lost in deep water and swept away by currents, you will have your deep channel. In other words, if you give the river some assistance by keeping its current together, it will do all the necessary labor and scour out its own bottom. This sound reasoning, based upon observation as sound, was duly embodied in a series of jetties which have proved successful.

Observation Suggests an Experiment.

Such a river as the Mississippi taking its source through an alluvial plain, has bends which go on increasing by the wearing away of the outer banks, and the deposition of mud, sand and gravel on the inner bank. In 1876 at the Glasgow meeting of the British Association for the Advancement of Science, Professor James Thomson showed a model which made the phenomena of the case perfectly clear. A stream eight inches wide and less than two inches deep, flowed round a bend. As it turned this bend the water exerted centrifugal force, while a thin layer of the water at the bottom, representing a similar layer close to a river-bed, was retarded by its friction with the remainder of the stream, exerting less centrifugal force than like portions of the larger body of water flowing over it farther away from the bottom. Consequently the bottom layer flowed in obliquely across the channel toward the inner bank; rising up in its retarded motion betwixt the fast flowing water it protected the inner bank from scour. At the same time this retarded current brought with it sand and other detritus from the bottom, duly deposited along the inner bank of the stream.

Instrumental Aids to Observation.

The powers of the eye, acute as they are, have narrow limits; inestimable therefore is the value of the microscope, the telescope and the camera which bring to view uncounted images otherwise unseen. Let us remark how in the early days of instrumental aids a great observer just missed noting a phenomenon of utmost importance,—the black lines of the solar spectrum, upon which Fraunhofer, an optician of Munich, based his spectroscope. In sending a solar beam through a lens and a prism Sir Isaac Newton admitted the rays through an oblong slit at times as narrow as one twentieth of an inch. He saw the familiar colors, from red to violet, and nothing more. Even with a crown lens, such as he probably used, four lines distinctly appear; that is, they appear to-day, to an observer who is looking for them. In 1802 these lines were observed, as far as we know, for the first time on record, by Dr. Wollaston, who drew six of them in a diagram accompanying a paper in the Philosophical Transactions. Four of these lines he regarded as boundaries of the colors of the spectrum; of the other two lines he attempted no explanation. He used prisms of various materials but found no alteration in the lines while he studied a sunbeam. When he employed candles or an electric light he found the appearances different, why, he could not undertake to explain. In 1814, Fraunhofer observed these lines in detail, mapped them, and proved that they identified elements long known to chemists. As he built his spectroscope he gave the chemist, the physicist and the astronomer an instrument of research worthy a place beside either the microscope or the telescope.

Dr. Wollaston, in 1802, as we have seen stood upon the threshold of spectroscopy without knowing it. During the same year he performed an experiment which took him into the field of photography without his recognizing the possibilities of that wonderful art. He took paper which had been dipped in muriate of silver and caught on its surface impressions of the ultra-violet light in a solar spectrum. These rays, as rings, were reflected from a thin plate of air, as in the case of the colors of thin plates, at distances corresponding to their proper places in the spectrum. Thus was established the close analogy between rays visible and invisible, and by a method destined to give mankind a universal limner in light of all kinds, and in much radiance which is not luminous at all.

Two Observers of the Skies.

Edward Emerson Barnard, of the Yerkes Observatory, Williams Bay, Wisconsin, is in the first rank of living astronomers. Among his many discoveries the most remarkable is that of the fifth satellite of Jupiter at the Lick Observatory. His early work at the Vanderbilt Observatory, Nashville, gave full promise of his later achievements. One evening in November, 1883, he was observing an occultation of the well-known star Beta Capricorni by the moon. He had patiently waited for his opportunity; such an occultation is best seen when the moon is a small crescent, the star disappearing at the dark curve of the moon where its beams do not overpower the feeble stellar ray. When the moon passes between the eye and a fixed star, the disappearance of the star is instantaneous. At the distance from which we look at it the star is a point only, and as the moon has no atmosphere, the instant the edge of the lunar surface touches the line joining the eye of the observer with the star, it vanishes from sight. When the moon passed in front of Beta Capricorni Mr. Barnard noticed that instead of disappearing at once, there was a sudden partial diminution of the light of the star, then a total extinction of the remaining point. The interval between the diminution and complete extinction of the light occupied only a few tenths of a second, but it was long enough to put his keen mind upon inquiry. Mr. Barnard in an astronomical journal called attention to the phenomenon and suggested that instead of there being only one star, as formerly supposed, there were really two stars so close together that in an ordinary six-inch telescope, such as he had used, they appeared to be one. He inferred also that one of the pair must be a good deal brighter than the other, because at the beginning the change in brightness was less than at the end. This surmise was soon afterward fully verified by Mr. S. W. Burnham with the eighteen and one half inch equatorial of the Dearborn Observatory at Chicago, revealing a close and unequal double star which would have remained unresolved had he used a less powerful instrument.

This Sherburne Wesley Burnham is the most successful discoverer of double stars who has ever lived. “The extreme acuteness of vision,” says Professor John Fraser, “which enables one to prosecute such research with the highest success is a very rare gift; and the discovery of close doubles, as in his case, is its severest test. To measure a star—that is, to ascertain by means of the micrometer the distance and position angle of the companion with reference to the principal star—is one thing, and to find new and close doubles is a very different thing. Baron Dembowski, the most noted measurer of double stars, had no success as a discoverer, and confessed his inability to find new doubles. When, however, a new double had been found by another observer, and the distance and position angle of the companion approximately estimated, he could readily find and accurately measure it. When Mr. Asaph Hall, in 1877, had found the two satellites of Mars and described their positions, it was not difficult for any astronomer who had access to a large Clark telescope to find them and see all that Mr. Hall had seen. The whole difficulty was in seeing them for the first time. Besides the ability to see a difficult object, there is required an intelligence and experimental knowledge of the subject, which are as rare as the visual faculty itself. Some of the lower animals have more acute vision than human beings; but they do not know all they see, or understand relations to other facts. They have plenty of sight, but they lack insight. Mr. Burnham’s powers in both these respects is extraordinary.”

At the Cape of Good Hope Observatory remarkable observations of double stars have been recorded. Sir David Gill, the director, says:—“At the Cape Observatory, as has always been the case elsewhere, the subject of double star measurement on any great scale waited for the proper man to undertake it. There is no instance, so far as I know, of a long and valuable series of double star discovery and observation made by a mere assistant acting under orders. It is a special faculty, an inborn capacity, a delight in the exercise of exceptional acuteness of eyesight and natural dexterity, coupled with the gift of imagination as to the true meaning of what he observes, that imparts to the observer the requisite enthusiasm for double star observing. No amount of training or direction could have created the Struves, a Dawes or a Dembowski. The great double star observer is born, not made, and I believe that no extensive series of double star discovery and measurement will ever emanate from a regular observatory through successive directorates unless men are specially selected who have previously distinguished themselves in that field of work, and who were originally driven to it from sheer compulsion of inborn taste.”

The Eye of a Naturalist.

It is sometimes said that the faculty of observation is a special gift with limitations, that the naturalist sees bones, feathers, shells because he is looking for them, while the armorer or the engineer but seldom gives a second glance to anything but guns, girders, or machinery.

To this rule we find striking exceptions. Edward S. Morse, of Salem, Massachusetts, is the foremost American expert in Japanese pottery. As a youth he was a railroad draughtsman in Portland, Maine, where his ambidexterity with the pencil and his discoveries in natural history brought him to the notice of Louis Agassiz. As a boy he was greatly interested in the shells of his native State; before he left school he had discovered and described a new species of land snail, Helix asteriscus, which the older naturalists had regarded as the young state of another and well-known species. At the same time he determined the distinct character of a most minute species, Helix minutissima, which had been described as such thirty years before, but which the later authorities had believed to be the young of another species. This faculty for discrimination led him to demonstrate a new bone in the ankle of birds which Huxley, and others, had supposed to be a process and not a separate bone. This discovery added another to the many reptilian characters which have been disclosed in the anatomy of birds. He also established beyond question that the brachiopods, always believed to be mollusks, are not mollusks at all, but are related to the worms. In Mr. Morse’s case we have either a man with a universal power of observation, or enjoying distinct faculties of perception, each usually appearing alone in an observer. Noticing a Japanese shooting a bow and arrow one day he took up the study of the attitude of the hand in pulling the bow. His memoir on this subject, with illustrations, has attracted world-wide interest. Pursuing this theme he examined an ancient object of bronze having three prongs, labeled as a bow-puller in European museums, showing that it had no relation whatever with the bow. Keenly susceptible to the beauty and variety of roofing tiles in Europe and the East, he has for the first time given them classification, and shown their ethnological significance. While teaching natural history at the University of Tokio he brought together the Japanese pottery now exhibited at the Museum of Fine Arts in Boston, unsurpassed as a collection in the world. His eye was as sharp in reading a potter’s mark, however worn and blurred, as when as a boy in Maine he defined minute species of land shells.

The Value of Collections.

Altogether commendable is the spirit which leads a boy or girl to collect and arrange shells, common wildflowers, seaweeds, and the diverse minerals brought to light in a railroad cutting. What is thus gathered, compared, and studied will leave a much deeper impression on the memory than what is seen for a moment in a museum or a public garden. And yet, to the profound student the museum is indispensable: he gives weeks or months to the contents of its cases, supplementing what he has learned in the field, by the seashore, in the woods. Take, for example, protective resemblances, one of the most fascinating provinces of natural history. Here is a hornet clear-wing moth. What has made it look like a wasp? Both share the same field of life, and while the wasp does not prey on the moth or in any perceptible way compete with it, the two insects have a vital bond. In its sting the wasp has so formidable and thoroughly advertised a weapon that by closely resembling the wasp the moth, though stingless, is able to live on its neighbor’s reputation, and escape attack from the birds and insects which would devour it if they did not fear that it is a stinging wasp. So far is the resemblance carried that when the moth is caught in the hand it curves its body with an attitude so wasplike as seriously to strain the nerves of its captor.

How came about so elaborate a masquerade? At first, ages ago, there was a faint likeness between the moth and the wasp; any moth in which that likeness was unusually decided had therein an advantage and tended to be in some measure left alone by enemies. In thus escaping it could transmit in an ever-increasing degree, its peculiarities of form and hue to its progeny, until in the rapid succession of insect generations, amid the equally rapid destruction of comparatively unprotected moths, the present striking similarity arose. Instances of this kind abound, forming some of the most attractive exhibits in the American Museum of Natural History of New York, and other great museums. Mr. W. H. Bates, who first explained these resemblances, did so as the result of comparing many various examples preserved in his cabinets at home, although, of course, his memory of habits observed in the field was indispensable. His ample collections enabled him to bring into view at once many captures separated by wide intervals of time and space. It was the opportunity thus afforded of taking a comprehensive survey of resemblances as a whole that led him to think out the underlying reason.

Accidental Observation.

Accident has played a noteworthy part in both discovery and invention. Nathaniel Hayward long ago remarked that sulphur deprives rubber of stickiness. Charles Goodyear one day combined some rubber and sulphur by way of experiment; quite by accident he overturned part of the mixture upon a hot stove. He saw in a moment that heat is essential to make rubber insensible to both heat and cold: he had indeed discovered vulcanization. Examples of this kind abound in the history of every art. As far afield as the war on insect pests in France a priceless discovery was hit upon unsought a few years ago. One autumn the vines were still suffering from phylloxera when a mildew caused by a fungus began to do serious damage to crops. Through the spraying of vines with blue-stone to prevent pilfering of fruit, it was noticed that the fungus was killed, leading to the most telling mode of attack on many of the pests which assail leaves, flowers and fruit.

James Hargreaves once saw a spinning-wheel overturned, when both the wheel and spindle continued to revolve on the floor. As he observed the spindle thus changed from a horizontal to an upright position it occurred to him that if a number of spindles were thus placed, side by side, several threads might be spun at once instead of a single thread. This was the origin of the spinning jenny; an invention which has parallels in the multiple drills, the gang-saws, and other machinery which take a task once executed by a single drill, saw or punch, and simultaneously perform it with ten, twenty, or a hundred drills, saws, or punches.

About thirty years before Josiah Wedgwood laid the foundation of his future eminence, a chance observation gave rise to improvement in the earthenwares of Staffordshire. A potter from Burslem, the centre of the potteries and the birthplace of Wedgwood, in traveling to London on horseback was detained on the road by the inflamed eyes of his horse. Seeing the hostler, the horse-doctor of those times, burn a piece of flint, and, having reduced it to a fine powder, apply it as a specific to the diseased eyes, it occurred to the potter that this beautiful white powder, if combined with the clay used in his craft, might improve the strength and color of his ware. An experiment succeeded, and so began English white ware, since manufactured on an immense scale.

More important than this discovery of a new use for flint powder was the discovery, also accidental, of electro-magnetism by Professor Oersted of Copenhagen. The incident is thus related in a letter to Michael Faraday from Professor Christian Hansteen:—

“Professor Oersted was a man of genius, but he was a very unhappy experimenter; he could not manipulate instruments. He must always have an assistant, or one of his auditors who had easy hands, to arrange the experiment; I have often in this way assisted him. In the eighteenth century there was a general thought that there was a great conformity, and perhaps identity, between the electrical and magnetical forces; and it was a question how to demonstrate it by experiments. Oersted tried to place the wire of his galvanic battery perpendicular (at right angles) over the magnetic needle, but remarked no sensible motion. Once, after the end of his lecture, as he had used a strong galvanic battery to other experiments, he said, ‘Let us now once, as the battery is in activity, try to place the wire parallel with the needle;’ as this was done he was quite struck with perplexity by seeing the needle making a great oscillation (almost at right angles with the magnetic meridian). Then he said, ‘Let us now invert the direction of the current;’ and the needle deviated in the contrary direction. Thus the great detection was made; and it has been said, not without reason, that ‘he tumbled over it by accident.’ He had not before any more idea than any other person that the force should be transversal.”

Granting that many important discoveries thus come about in ways beyond human foresight, accident alone will not produce an invention. As Dr. Ernst Mach reminds us, in every such case the inquirer is obliged to take note of the new fact, to recognize its significance, to detect the part it plays, or can be made to play, in a new structure, or in a novel and sound generalization. What he sees before him, others also have seen, perhaps many times; he is the first to notice it as it deserves to be noticed, simply because he has an eye earnestly desiring to behold just such a fact as this and use it to bridge a gap either in art or explanation.

Let us take a case where an accident, well observed, has meant a golden discovery. One day during a trip on the Thames in a steamer propelled by an Archimedean screw devised by Francis Pettit Smith, the propeller struck an obstacle in the water, so that about one half of the length of the screw was broken off; it was noticed that the vessel immediately shot ahead at a much quickened pace. In consequence of this discovery, a new short screw was fitted to the vessel and with this new propeller the steamer went uniformly faster than before.

Perforated Sails for Ships.

In craft built ages before steamers were designed, fishermen have observed that sails torn in the middle, if the rents were not too big, were more effective than when new and whole. What thus began in sheer wear, or accidental damage, is now imitated of set purpose. Under the equator one may often see small craft whose sails are matting woven with large openings, as the sailors say “to let out the wind.” The mariners of Carthegena, St. Thomas, and other islands of the West Indies, know that a ship goes better thus than if her sails were each one continuous breadth of canvas. Japanese junks of clipper builds have sails made of vertical breadths laced together so as to leave large apertures free to the air. Why is this breeziness of structure profitable? Because against the concave surface of an ordinary sail the wind rebounds so as to hinder its impulsive effect; through an aperture the air rushes in a continuous current and no rebound takes place. For a like reason, and with similar gain, Chinese rudders are made with separated boards or planks. The stream of water passing through such a rudder would exert an undesirable back pressure in a rudder of solid form.

It would be interesting, and might prove gainful, to experiment with perforated sails in sail-boats, ice-boats and wind-mills. In large kites, sent to the upper air by meteorologists, it has been found helpful to give the fabric a few small perforations.

Observations Must be Remembered and Compared: The Value of a New Eye.

It is not only necessary to observe if one would learn, one must remember and compare observations. In a cycle of 223 lunations all the motions of the moon are repeated; it is astonishing that astronomers in Chaldea detected this period, exceeding eighteen years as it does. On the other hand, one of the most striking phenomena of a solar eclipse, its revelation of the solar corona, does not seem to have been noticed until comparatively recent times. The first known record of it is by Lobatchevsky, July 8, 1842.

There is value in the teaching which teaches the eye what to observe; at times there is gain in a freshness of view unwarped by ideas as to what deserves to be inspected and what does not. Dr. Priestley, one of the founders of chemistry, says:—“I do not at all think it degrading to the business of experimental philosophy to compare it, as I often do, to the diversion of hunting, where it sometimes happens that those who beat the ground the most, and are consequently best acquainted with it, weary themselves without starting any game, when it may fall in the way of a mere passenger; so that there is but little room for boasting in the most successful termination of the chase.” True, yet this discerning eye will always be found beside a brain of uncommon force and sweep. Mr. Edwin Reynolds, of Milwaukee, as related in this book, never saw a mining stamp until the morning when he planned a bold and profitable simplification of it. Professor Alexander Graham Bell, who invented the telephone, came to his triumph not as a disciplined electrician, but as a student, under his father, of articulate speech and its transmission. He has told me that had he known the obstacles to be surmounted, he would never have begun his attack.

Professor Ernst Abbe, of Jena, who more than any other investigator is to be credited with the production of Jena glass, was at the outset of his labors quite ignorant of practical optics. But he had a thorough mastery of mathematical optics, and this in due season enabled him to revise the theory of the microscope, and to prescribe the conditions according to which the manufacture of totally new kinds of glass should proceed. Every one of these men, every peer they have ever had among the volunteer forces of research, is far removed in native ability, in plasticity of mind, from Priestley’s “mere passenger.” If ignorance by itself were the chief qualification for discovery, science would long ago have entered upon its golden age.

Any Observation May Have Value.

Michael Faraday, that consummate observer, held that at times the observations of comparatively untrained men are well worth attention. In one of his note-books he wrote:—“Whilst passing through manufactories and engaged in the observance of the various operations of civilized life, we are constantly hearing observations made by those who find employment in these places, and are accustomed to a minute observation of what passes before them which are new or frequently discordant with received opinions. These are frequently the result of facts, and though some are founded in error, some on prejudice, yet many are true and of high importance to the practical man. Such of them as come in my way I shall set down here, without waiting for the principle on which they depend; and though three fourths of them ultimately prove to be erroneous, yet if but one new fact is gathered in a multitude, it will be sufficient to justify this mode of occupying time.”

Folk Observation Foreruns Science.

Often a conviction widely held by the plain people of a countryside is based on many and sound observations, long before a scientific theory accounts for the facts. For many generations there was a saying among German peasants that when a storm is approaching a fire should be made in the stove, with as much smoke as possible. Professor Schuster has shown that this saying and the custom founded upon it are rational, as the products of combustion and the smoke act as an effective conductor to discharge the atmosphere slowly but surely. He quotes statistics showing that out of each 1000 cases of lightning stroke, 6.3 churches and 8.5 mills were struck, and but 0.3 factory chimneys. Only the factories had fires burning.

A mighty work has been wrought by glaciers on the surface of our globe. Long before this fact was discovered by professional geologists it was clear to many of the plainer people. Jean de Charpentier, one of the first propounders of the theory of glacial action now fundamental in geological science, relates:—“When in the year 1815, I returned from the magnificent glaciers of the valley of the Rhone, I spent the night in the hamlet of Lourtier, in the cottage of Perraudin, a chamois-hunter. Our conversation turned on the peculiarities of the country, and especially of the glaciers which he had repeatedly explored and knew most intimately. ‘Our glaciers,’ said Perraudin, ‘had formerly a much larger extent than now. Our whole valley was occupied by a glacier extending as far as Martigny, as is proved by the boulders in the vicinity of this town, and which are far too large for the water to have carried them thither.’” Charpentier adds that he afterward met with similar explanations on the part of mountaineers in other sections of Switzerland.

Cowpox was long observed by English country folk to be a preventive of smallpox. It was in hearing a servant woman say so that Dr. Jenner was drawn to the study which ended in his successful vaccinations, in all the triumphs since won in this department of medical science. For two thousand years the peasants of Italy have suspected mosquitoes and other insects to be concerned in the spread of malarial and other fevers. It remained for Dr. Ronald Ross in our day to prove that the suspicion was founded in truth. In “The Naturalist in La Plata,” one of the best books on natural history ever written, Mr. W. H. Hudson says:—“The country people in South America believe that the milky secretion exuded by the toad possesses wonderful curative properties; it is their invariable specific for shingles—a painful, dangerous malady common amongst them, and to cure it living toads are applied to the inflamed part. I dare say learned physicians would laugh at this cure, but then, if I mistake not, the learned have in past times laughed at other specifics used by the vulgar, but which now have honorable places in the pharmacopoeia—pepsine, for example. More than two centuries ago, very ancient times for South America, the gauchos were accustomed to take the lining of the rhea’s (a large ostrich’s) stomach, dried and powdered, for ailments caused by impaired digestion; and the remedy is popular still. Science has gone over to them, and the ostrich-hunter now makes a double profit, one from the feathers, and the other from the dried stomachs which he supplies to the chemists of Buenos Ayres. Yet he was formerly told that to take the stomach of the ostrich to improve his digestion was as wild an idea as it would be to swallow birds’ feathers in order to fly.”

Snake poison has long been used by the Hottentots as an antidote to snake poison. With aid from the Carnegie Institution of Washington, Dr. Hideyo Noguchi, of the University of Pennsylvania, has succeeded in producing antivenins, to use the medical term, for the venoms of the water-moccasin and Crotalus adamanteus snakes, using the venoms themselves in preparing his antidotes. He is continuing his researches in this remarkable field of the healing art.

Kelp, as it drifts and sways in the Atlantic, attracts from the sea both the iodine and the bromine dissolved in minute quantities in the sea-water. This trait of fastening upon a particular and rare element is displayed by plants on land as well as by sea-weeds. In the Horn silver mine of Utah, the zinc mingled with the silver is betokened by the abundance of a zinc violet, Viola calaminaria, a delicate cousin of the pansy. In Germany this little flower was believed to point to zinc deposits long before zinc was discovered in its juices. The late Mr. William Dorn, of South Carolina, had faith in a bush of unrecorded name, as declaring that gold veins stood beneath it: that his faith was not baseless is proved by the large fortune he won as a gold miner in the Blue Ridge country—his guide the bush aforesaid. Mr. Rossiter W. Raymond, a famous mining engineer of New York, has given some attention to “indicative plants” of this kind. He is of opinion that their unwritten lore among practical miners, prospectors, hunters, and Indians is well worth sifting.

He says:—“Judging from the general laws of the distribution of plants, and from the analogy furnished by Viola calaminaria, we may expect that an indicative plant will be, not a distinct species, but a variety of some widely distributed species, the range of the species as a whole being determined by general conditions of climate, altitude and soil, while the characteristics of the variety are affected by causes peculiar to the mineral deposit. Temperature and moisture, as Agricola long ago pointed out, are among these causes, and color is one of the most sensitive of their effects. It is quite reasonable to believe the soil may affect the color of the plant absorbing it. On the other hand, it is not certain, even if a plant is proved to indicate by color or other peculiarities the presence of silver, that silver is the substance actually entering into and altering the plant. The effect may be due to some other mineral substances associated with the silver-ores; and our silver-plant may be indicative of silver in a silver region only.”

Mr. Raymond remarks that a general relation between the flora and the geological formation of any given district is a fact familiar to field-geologists. Many plants, too, indicate the neighborhood of water. A botanist knowing the root-length, water-requirements and habits of different species can often determine from the surface vegetation, he tells us, the nature, amount and distance of the underground water-supply.[33]

How observation may lead to a bold and successful experiment is told by Mr. L. E. Chittenden, Register of the Treasury under President Lincoln, in his Personal Reminiscences:—

A Lesson from a Bank-Swallow.

Between the Winooski Valley and Lake Champlain, north of the city of Burlington, lies a broad sand plain high above the lake level, through which the Central Vermont Railroad was to be carried in a tunnel. But the sand was destitute of moisture or cohesiveness, and the engineers, after expending a large sum of money, decided that the tunnel could not be constructed because there were no means of sustaining the material during the building of the masonry. The removal of so large a quantity of material from a cut of such dimensions also involved an expense that was prohibitory. The route was consequently given up and the road built in a crooked ravine through the centre of the city, involving ascending and descending grades of more than 130 feet to the mile. When the railroad was opened these grades were found to involve a cost which practically drove the through freights to a competing railroad.

There was at the time a young man in the engineers’ office of the railroad who said that he could tunnel the sand bank at a very small cost. He was summoned before the managers and questioned. “Yes,” he said, “I can build the tunnel for so many dollars per running foot, but I cannot expect you to act upon my opinion when so many American and European engineers have declared the project impracticable.” The managers knew that the first fifty feet of the tunnel involved all the difficulties. They offered him, and he accepted, a contract to build fifty feet of the structure.

His plan was simplicity itself. On a vertical face of the bank he marked the line of an arch larger than the tunnel. On this line he drove into the bank sharpened timbers, twelve feet long, three by four inches square. Then he removed six feet of the material and drove in another arch, just inside the first one, of twelve-foot timbers, took out six feet more of sand, and repeated this process until he had space enough to commence the masonry. As fast as this was completed the space above it was filled, leaving the timbers in place.

Thus he progressed, keeping the masonry well up to the excavation, until he had pierced the bank with the cheapest tunnel ever constructed, which has carried the traffic of a great railroad for thirty years, and now stands as firm as on its completion.

The engineer was asked if there was any suggestion of the structure adopted by him in the books on engineering. “No,” he said, “it came to me in this way. I was driving by the place where the first attempts were made, of which a colony of bank-swallows had taken possession. It occurred to me that these little engineers had disproved the assertion that this material had no cohesion. They have their homes in it, where they raise two families every summer. Every home is a tunnel, self-sustaining without masonry. A larger tunnel can be constructed by simply extending the principle, and adopting masonry. This is the whole story. The bank-swallow is the inventor of this form of tunnel construction. I am simply a copyist—his imitator.”