May 1, 1885.] 



♦ KNOWLEDGE ♦ 



361 



MAGAZINE OF SCIENCE 

 PlainlyWorded-ExactlyDescribed 



LONDOX : FRIDAY, MAY 1, 1885. 



Contexts ok 2s' o. 1; 



The PhUo»ophT of Clothing. VII. 



Bj W. Mattiea Willisms 3CI 



A DmHoe Lottery Sirindle. By R. A. 



Proctor S62 



Criticml Methods of Delectinp Errora 



in Pkne Surfaces. (7//u...) 363 



ThoaKht an.i Language. VIII 3t>5 



Erriution of the Sense of Beauty. 



BtC. C.W.Naden 366 



Migration of Hlovring Vipers. (JUu.) 368 



Other Worlds than Ours 



Amateur Photocraphic Exhibition. 

 The International Inventions Exhi- 

 bition. [With Plan.) 



Modem Domestic Economy 



Editorial Gossip 



Reviews 



Correspondence 



Our Inventors' Column 



Our Chess Colamn 



• ei 



3U9 

 370 



371 

 375 

 378 

 378 

 378 

 381 

 382 



THE PHILOSOPHY OF CLOTHING. 



By "W. Mattieu Williams. 



VII.— BUMFORD'S KXPERIMENTS ON CLOTHING 

 MATERIALS. 



THE experiments already described were directed to the 

 determination of the relative protecting power of 

 diflFerent materials. These were followed by another series 

 upon certain given materials differently arranged, or in 

 different conditions of density. The same " passage ther- 

 mometer " 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, cotton, <tc., did all the obstruc- 

 tive 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 bulb of the thermometer, it was easy 

 to increase their quantity by packing them more closely, 

 and yet retaining the other conditions of bulk, itc, the same. 

 The material selected for the first series of experiments 

 was eider-down. It was placed round the bulb of the ther- 

 mometer, occupying tiie space between it and the outer 

 globe, but so packed that the quantities therein were 

 16 grains, 32 grains, and 64 grains respectively in the 

 different experiments. The following were the results, the 

 times of cooling shown in seconds : — 



It is evident from these results 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 propor- 



tionately retarded, the time for Gf grains should have been 

 1,301 x 4 = ,"),l!l() seconds instead of only 1,G15 seconds. 



The following displays the results obtained by using the 

 same material, in the same quantity, but did'erentjy disposed. 

 The tirst-nanied, the raw silk, was very fine, and <-<iually 

 distributed throuj^hout the space it occupied ; the second, 

 the ravelliiignof tatl'ety, were also fine, but not so lino as the 

 raw silk, and, of course, the interstices between its threads 

 were greater ; the cultiugs of sewing silk on the thin! 

 were very coarse, and, consequently, the material was very 

 unequally distributed in the space in which it was confined. 

 In the fourth the same quantity of sewing-silk, instead of 

 being distributed through the space between the bulb and 

 globe, was wound round the bulb of the thermometer, 

 forming a tightly-titting jacket, entirely covering it, and 

 as nearly as possible of the same thickness in every part 

 The time of cooling each 10 degrees is shown in seconds. 



Here the clothing efficacy of a given quantity of silk is 

 shown to diminish with its closeness of texture. 



There is, however, a curious anomaly displayed by these 

 experiments. The protective superiority of the loosely- 

 arranged fibres of silk is greater at the first cooling down 

 from the higher temperatures, and gradually diminishes as 

 the temperature lowers. This is the most strikingly shown 

 by comparing the fourth and fifth columns, the loose 

 sewing-silk and the tightly-wrapped sewing-silk. Between 

 70° and 60° the superiority of the loose silk is as 67 to 42 ; 

 this ratio diminishes progressively until equality is nearly 

 reached between 30" and 20°— i.e., 105 to 191. Between 

 20° and 10° the relations are reversed, the tightly-wound 

 silk having the advantage in the ratio of 399 to 342. That 

 this is not an error of experiment, or a peculiarity of silk, 

 was shown by subsequent experiments on other materials. 



The quantity used in the following experiments were the 

 same as before, viz., 16 grains; the sheep's wool, cotton wool, 

 and lint placed round the bulb of the thermometer, filling 

 the space between it and the outer globe ; the different 

 kinds of thread wound closely round, and the fine linen 

 cloth wrapped nine times round the bulb, and bound 

 together at the top and bottom, so as to cover it. 



