




ON THE LAWS OF THE CONDUCTION OF HEAT. 261 
_ (continued.) 
July. August. September. October. November. December. 








rature| Rain. 
of the of the 
day. . day. 
a y, in 
1°78 | 85°9 88°3 86° 76°2 66 59°4. 
86 85°6 86°6 80°9 64°6| .. | 59°2} o712 
3°00 | 81°8 . 81°9 83'5 78'4 59°5| 1°90 | 57°4| oO°50 
ine oe 1°5 
864 89°1 87°5 776 64 o*60 | 59°4| o*10 
1°54 | 87°3 90°3 go'l 82° 66°4.| x09 | 60°4 
1°25 | 87°5 906 : 82°6 68°5| 1°35 | 60°6| o'25 
+ | 95°5 88°7 87° 74 60°6 57°5 
0°98 | 92°1 904 o. 57°9 58 
3°79 | 85°5 83°2 85°7 76°2 45° 
-- | 684 66°7 62°1 62°8 
ge 84° 55° 
88°3 g2"1 88-7 85 67° 61 
84°1 81°7 84° 64°5 58°6 
oe 62° 
ee 63° 
: a .. 89°5| = + 82° 25 . he 58° 
223) tak ORTH at Mage O2 ail Merk S6sg)}) Pe. 68°4 
ee «= | | 8675) 4. 81° os . a 56° 
93 93° 67 


of heat through the solid is not in a simple direct proportion to the difference 
of temperature of two contiguous thin slices, but varies in a less rapid’ pro- 
portion; or, the conductivity diminishes as the temperature increases. My 
experiments were so framed as to give the numerical relation between the 
conductivity and the temperature ; but though the numbers, given by expe- 
riments under circumstances essentially different, substantially agree, I do 
not as yet feel justified in assigning a numerical value to the effect of tem- 
perature on the conductivity of iron, until the possible disturbing effect of 
the cause which I have mentioned shall be better ascertained. 
I take this opportunity of expressing my acknowledgements to Professor 
Kelland for the advice which he has, with his usual kindness, from time to 
time afforded me. I still hope to be able to renew these experiments, and 
I shall not cease to devise plans for their improvement ; in the meantime I 
Intend to put on record both the principles of the method and the direct 
results obtained, as well as the reductions; and also the manipulations which 
experience has taught me, and which I believe will be found of use to any 
future observer. 
Ambleside, 25th August, 1852. 

