Heat by Conduction in Bone, Brain-tissue, and Skin. 185 



Percentages of heat transmitted, deduced from the above values. 



Times. 



Averages. 



Maxima. 



Minima. 



2 „ „ .... 

 4 „ „ .... 

 6 „ „ .... 



16-090 per cent. 

 36-523 

 59-874 

 78532 



23-541 per cent. 

 50-378 

 77-864 

 91-287 



8-804 per cent. 

 20543 

 26969 

 46-187 



This table shows that already by the end of one minute and a 

 quarter the thermal transmission was, on an average, very marked, 

 and that at the end of the sixth minute, 78^ per cent, of the initial 

 difference of temperature had been made up. It will further be seen 

 that these results are widely at variance with those of M. Franck, 

 the latter having failed to obtain, at the end of fifteen minutes, using 

 thermometers detecting O- 05 C, any indication of conduction through 

 only 3 millims. of bone, with a difference of temperature of 1° C. ; 

 while, according to the table, a change of nearly 0°'06 C. was found, at 

 the end oi four minutes, through 7'5 millims. of bone, with a difference 

 of only 0°'l C. 



(c.) The maximum change of temperature produced when the per- 

 manent thermal condition is attained. 



"We have under this heading to consider the thermal condition of 

 the bone at the time when the flow of heat through it has settled into 

 a regular and steady movement, in which each cross section of the 

 conductor receives and transmits equal quantities. 



We have first to inquire how long a time is usually occupied in the 

 attainment of this condition. 



With the differences of temperature specified under the heading (a) 

 the time ranged from 9 minutes to 11 minutes 30 seconds, the average 

 of all the times being 9 minutes 53 seconds. In 42 "85 7 per cent, of 

 the cases it was 9 minutes, in 28 - o72 per cent, it was 10 minutes, in 

 14*285 per cent, it was 11 minutes 30 seconds, while the remaining 

 14*286 per cent, was divided equally between 11 minutes and 10 

 minutes 30 seconds respectively. 



Table II gives the effects of the transmission at this period, reduced 

 to values representing 0°'l C. difference of temperature. 



