By Mattieu Williams.

The following extracts are from the experiments and conclusions of Rumford, with supplements by Prof. Mattieu Williams, of England. (See "Knowledge," Nos. 171 to 205, "Philosophy of Clothing.")

The physiological confirmation of these results are not quoted; confining the citations to the qualitative value of fibres, especially sheep's wool, and the possibility of materials therefrom that possess the essentials recommended.

The first use of clothing being to keep the wearer warm, Rumford's first inquiry was directed to find the best material for this purpose. He saw at once that clothing did this by resisting the passage outwards of the animal heat.

He accordingly constructed a model wearer, as described in the following experiments: A mercurial thermometer, whose bulb was 55/100th of an inch in diameter, and its tube about ten inches long. This was suspended in the axis of a cylindrical glass tube about three-quarters of an inch in diameter, ending with a globe 1 6/10 inch in diameter, in such a manner that the center of the thermometer bulb occupied the center of the globe, thus leaving a surrounding space to be occupied by the material to be examined. The thermometer tube was graduated with 800 divisions between the freezing and boiling points of water—i. e., a Reaumur scale divided to tenths of degrees. The thermometer was held in its place by a long cork stopper.

He described his method of clothing the bulb as follows: The thermometer being taken out of the cylindrical tube, about two-thirds of the substance which as to be the subject of the experiment is introduced into the globe; after which the bulb of the thermometer introduced a few inches into the cylinder; and after it, the remainder of the substance being placed round about the tube of the thermometer: and lastly, the thermometer being introduced further into the tube, and being brought into its proper place, that part of the substance which, being introduced last, remains in the cylindrical tube above the bulb of the thermometer, is pushed down into the globe, and placed equally round the bulb of the thermometer by means of a brass wire, which is passed through holes made for that purpose in the stopple closing the end of the cylindrical tube.

The temperature he selected as the starting point was 70 degrees Reaumur=190 degrees Fahr. He preferred this to the boiling point, as he could obtain it accurately by first plunging the whole apparatus duly charged into nearly boiling water, then allowing it to fall to 70 degrees, and immediately plunging it into a mixture of pounded ice and water, where, by the aid of a little agitation, it remained steadily at the freezing point.

The following table shows the results with the substances therein mentioned, the quantity in each case being 16 grains:

The clothing value or "warmth" of these substances as thus applied varies directly with these figures, representing the passage of heat or their "non-conducting" power.

The experiments described were directed to the determination of the relative power of different materials. (We have only quoted the substances most generally used for clothing purposes.) These were followed by another series upon certain given materials differently arranged, or in different conditions of density. The same "passage thermometer" was used. The question to be determined was, whether the protecting power of the substances used in the previous experiments was due to the non-conduction of the material of those substances themselves, or whether the air imprisoned between their fibres was an important factor. If the silk, wool and cotton did all the obstructive work independently of the air, then the amount of obstruction should vary with the quantity of fibre. As, in the experiments already described, the fibres were loosely arranged round the bulk of the thermometer, it was easy to increase their quantity by packing them more closely, and yet retaining the other conditions of bulk, etc., the same.

It was evident from the results, with 16 grains, 32 grains, 64 grains, that the protective power does not increase nearly in the same proportion as the quantity of material when packed in the same space. Had such been the case, and the rate of cooling proportionately retarded, the experiment (with eider down from the duck) with 64 grains should have been 1,304x4 5,216 seconds, instead of only 1,615 seconds.

The following displays the results obtained by using the same material, in same quantity, but differently disposed, 16 grains of each:

From this it is to be seen that sheep's wool loose would retard the passage of heat more perfectly than when spun into thread.

The "Jaros Hygienic Material" of sheep's wool unspun worn next the body possesses the essentials for non-conduction of heat in a manner described.

It is an instance how an effort to apply pure science to practical business may react in such manner that practical business shall become a beneficent contributor to pure science.

Another practical question suggested is: Whether clothing materials differ in their powers of absorbing the cutaneous exhalations; if so, which are the most effective, and what are the relations of this function to that of confining air, and thereby maintaining the temperature of the body? If these two functions are opposed, then how shall we effect a compromise? If, on the other hand, they go together in any special material, the desirability of using this material is doubly indicated.

Sheep's wool does absorb (see Knowledge 191) the aqueous vapor. Loosely distributed fibres of wool in a suitable fabric take hold of the vapor of the insensible perspiration in the gaseous form, and by virtue of gaseous diffusion continually exchange this with the gasses of the outer atmosphere.

The conclusion, therefore, is that such a material is best suited for clothing, both in winter and summer.

Sir John Billingall (lecturer on Military Surgery) mentions his experience in India, and the proof of the utility of wool in checking the progress of a most aggravated form of dysentery in the Second Battalion of the Royals. The result of this has led to the enforcement of the use of belts for tropical service. Mr. Sage of the Army Clothing Depot at Pemlico, tells me many thousands have lately been made there.

My experience and subsequent observations have proven that, although loosely woven flannels may advantageously prevent the sudden chills from the evaporations of accumulated perspiration, this is better done by a knitted fleecy wool fabric worn next the skin.

Jaros Hygienic Material,

wool fleece knit.