188 Dr. J. S. Lombard. On the Propagation of 



Percentages of heat transmitted, deduced from the above values. 



Times. 



Averages. 



Maxima. 



Minima. 



1 min. 15 sec. . . 



2 „ „ 



4 „ „ .. 

 6 „ „ 



14-176 per cent. 

 28-803 

 50-459 

 66-799 



21-875 per cent. 

 39-825 

 69-581 

 91-696 



4 - 294 per cent. 

 13-066 

 21951 

 33-450 



Times. 



Thermometric degree 

 of average superiority 

 of skull over brain. 



Percentages of degree 

 of average superiority 

 of skull over brain. 



2 „ „ 



4 „ „ 



6 „ „ 



00191° C. 

 0-00772 

 0-00942 

 001174 



1*914 per cent. 

 7-720 

 9-415 

 11-733 



Comparing the maximum values of the two tables (land III), it will 

 be noticed that at the end of the sixth minute the brain-tissue exceeds 

 the skull by 0° "00042 C. 



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

 permanent thermal condition is attained. 



First, as to the time required to reach this condition, with the 

 differences of temperature set down under the heading (a), the range 

 was from 9 to 11 minutes, the average of all the times being 9 minutes 

 52'5 seconds. In 50 per cent, of the cases it was 9 minutes, in 37*5 

 per cent, it was 11 minutes, and in the remaining 12*5 per cent, it was 

 10 minutes. 



In Table IV we have the results of the transmission at this period, 

 reduced, as in the case of the skull, to values representing o, l C. 

 difference of temperature. 



Table IV. — Permanent thermal condition effected by 0°'l C, through 

 7'5 millims. of cerebrum of sheep. 1° of galvanometer is equal to 

 0°-0006742 C, and0°'l C. is equal to 148°'316 of galvanometer. 





Degrees of 



Thermometric 



Percentages of 





galvanometer. 



values. 



heat transmitted. 





113 029° 



0-07620 C. 



76 208 per cent. 





138-888 



0-09364 



93-638 





72-000 



0-04854 



48-545 



