THICK OR THIN BLANKETS

Evening Post, Volume CIX, Issue 131, 6 June 1925, Page 16

THICK OR THIN BLANKETS

• WHICH &REBEST FOB GOOD '- , ; ; w : HEALTH? Teats made, recently'by the Bureau of Standards" at'-Washington show "that blankets, of moderate density keep the indoor- sleeper "-warmer than those which are closely -woven- or ..dense ;,.also.. tijat . cotton Mankets. can bo used over sheets to good advantage by all except those who, like campers, sleep where it is damp. Blankets have been, used by man for so many thousands of years that they have become a commonplace. | Few scientific tests have ever been -made j on them. Most people take it for granti ed that a thick blanket is warm, esj pecially if it is tightly, woven, and that i a. thin blanket is correspondingly colder, , says the "Scientific American." Withjin certain limits this is true. But there i is such, a thing, saya the bureau, as put-j-ting so much 6bre into the blanket and thus leaving so little space between the fibres that the fibres themselves become conductors.of heat. Thus the blanket actually,cools us, just as-tfie thin cooling nns of an automobile radiator cools the tubes and the-water within them. What-, in a scientific sense, is a blanket? It is only a convenient device for surrounding ourselves with several lay-ers-of non-conducting bubbles of air Air is the best insulator of heat that is available.: ;• Ifis also" the cheapest. The tmy spaces between the fibres of tho blanket constitute these insulating air cells. -What we want in a blanket is tie correct balance, between the size of the air spacesand the'space taken up by the fibres. If there are too few fibres the a r will . pasß 3a and out of the contained air cells too freely. ■- We shall always be warming up new air If on the other hand. Lherp arc too many £?',fcT WI bB litUo sp:ice IcFtfor tliP fih' ?i SCt ? SUU ins "'«^V while away from om- bodies.;. When we wish to sleep in the wind or in a strong draught, we must prevent the pressure aJI ■ V" 5 an: fn»m'Wivin S ont tho mmmw4