MEASUREMENTS 



325 



SUBSTANCES 



AUTHORITY 



fO-0000500 Winkelmann (Wied. Ann, 1880 



Air < vol. x., p. 668). 



[>0000532 Rubner (see 170). 



Copper 1 -0400000 H. F. Weber 



Iron 0-1587000 Berget (Comptes Rend. Sc. tr., 



cvii., p. 227, 1888) 



Marble 0-0018000 Forbes Prco. Ed. Soc., 1872-75). 



0-0022000 Herschell 



Chalk fO-0002900 (*) Lees (Proceed. Bay, Soc., 1901, 



tr Ixxiv.) 



Oak 1 0-0001300 ( 2 ) 



^0-0001500 ( 3 ) 



Maple ( - 003500 

 \ 0-0001500 



Pine, fir tree 0-0000900 Forbes (loc. cit.) 



Cork 0-0001300 Forbes, Mauro (// Polidermes, 



Dec., 1910) 

 Hard gum 0-0000890 Stefan (Wien Ber, vol. Ixxiv., p. 



438, 1879. 



Beeswax 0-0000870 Frobes (loc. bit.) 



Horn 0-0000870 



Pasteboard ... 0-0004530 



Paper 0-0003100 Lees (loc. cit.) 



Vulcanised 



Rubber 0-0000890 Forbes (loc. cit.) 

 Woodsawdust( 4 ) 0-0001230 



Felt 0-0000900 



Wool 0-0000550 Lees (loc. cit.) 



0-0000400 Forbes (loc. cit.) 

 Compressed 



cotton 0-0000330 

 Cotton (loose) 0-0000433 

 Cotton wool 0-0001250 Mauro (loc. cit.) 



Olive oil 0-0003900 Waschmull (Phys. Zelt., 1901, 



vol. Ill, p. 79) 

 Snow 0-0003600 Okada (Meteor Zeit., 1905, vol. 



xxii., p. 336 



For ordinary clothing, Rubner's table ( 170) is the most trust 

 worthy. The co-efficient of protection ( 172) or the heat trans- 

 mitted by a tissue, must depend on the thickness of that tissue. 

 But it must be pointed out that the volume of air imprisoned 

 in fur is very important as a heat insulator., even though the 



(*) Parallel to the fibres. 



( a ) Perpendicular to the fibres and following a medullary ray. 



( 3 ) Perpendicular to the fibres and to a medullary ray. 



(') For fir tree sawdust Mauro (loc. cit.} found a higher value O'OOO, 1830. 



