500 
MR. C. H. LEES ON THE THERMAL CONDUCTIVITIES 
Mica, large plate, *18 cm. thick. Thermal stream lines perpendicular to cleavage 
planes. Air, 15°‘G C. 
Cool bar. 
Hot bar. 
v-y 6'36 Aj 6'58 
v. 2 2'77 Q x 1093 
fr _ : 1093 x '18 x L002 _. nA1 , 4 
18-90 A 2 18'67 
t'o 27 44 Qo '1436 
■1436 x AS x 1' 0 °2 _ 
18'67 — 6'58 x 1'05 
8 18'67 x 1-05 - 6-58 
Te mean = '00181. 
As the mica was in the form of a large plate, the above method of finding k is not 
strictly correct, and this accounts for the difference between the calculated values of 
k y and k 2 . It was found impossible to use a disc, as in the other experiments, on 
account of the mica splitting. The value of k given must be taken as approximate 
only. 
III. Rock Specimens. 
Marble Disc, l - 93 cm. diam., '26 cm. thick. The marble was the white 
variety used for statues. Air, 15°*5 C. 
Cool bar. 
Hot bar. 
Vy 10-15 Ay 10-40 
v 2 4-38 Qy -1767 
lc — '17t)7 x -26 x 1-001 _ .00000 
Vy 17-31 A 3 17-01 
v. 2 27 27 Q 3 -1839 
j _ -1839 x -26 x l’OOl _ .QQ^jg 
1 17-01 - 10-4 x 1-003 
3 17 01 x 1-003 - 10-4 
Tc mean = '00709. 
Slate Disc, I *93 cm. diam., ‘31 cm. thick, cut from an ordinary school slate. 
Air, 14°-9 C. 
Cool bar. 
Hot bar. 
Vy 8-80 Ay 9-08 
v 2 4-27 Q, -1508 
. /, _'-150Sx -31 x 1-002 _ 
vy 19-40 A 3 19-15 
v 2 28-58 Q, "1581 
j -1581 x -31 x 1"002 _ .QQ432 
1 19-15 -9-08 x 1-006 
a 19-15 x 1-0U6 - 9-08 
k mean = '00475. 
