Heat by Conduction in Bone. Brain-tissue^ and Skin. 187 



it was 38 seconds, in 22*223 per cent, it was 30 seconds, and in the 

 remaining 5"556 per cent, it was 53 seconds. 



If all the individual results are reduced to values representing 

 0°'l C. difference of temperature, the average time becomes 40*49 

 seconds, the maximum and the minimum being respectively 63*706 

 and 27*646 seconds. The average rate of the thermal movement is, 

 therefore, 1 millim. per 5*3986 seconds, the maximum and the 

 minimum times being respectively 8*4941 and 3*6853 seconds. There 

 appears indeed from these figures to be but little difference at this 

 period between brain and skull. 



(6.) The degree of change of temperature produced at certain 

 measured intervals of time. 



Proceeding in precisely the same manner as in the case of the skull, 

 we arrive at the results set forth in Table III. These results are evi- 

 dence of the accuracy of M. Franck in attributing a high conducting 

 power (comparatively speaking) to brain- tissue ; for the values given 

 in the table approximate closely, especially in the earlier periods, to 

 those contained in Table I for the skull. If we take the differences 

 between the thermometric values at the same periods in the averages 

 of the two tables, we find that the superiority of bone over brain- 

 tissue is represented, even at its greatest, by only a little more than the 

 one-hundredth of a degree Centigrade. The average degree of supe- 

 riority of the bone over the cerebral tissue in point of conductivity at 

 the different periods will be seen below : — 



Table III. — Effects of 0°*1 C. difference of temperature through 7* o 

 millims. of upper surface of cerebrum of sheep. 1° of galvanometer 

 is equal to 0°*0006742 C. ; and U 3 T C. is equal to 148 3 *316 of gal- 

 vanometer. 



Time from the 

 moment of 

 contact of copper 

 plate, on which 

 the piece of 

 brain rested, 

 ■with the •water. 



Averages. 



Maxima. 



Minima. 



Degrees 



of 



galvano- 

 meter. 



Thermo- 

 metric 

 Tallies. 



Degrees 

 of 



galvano- 

 meter. 



Thermo- 

 metric 

 values. 



Degrees 

 of 



galvano- 

 meter. 



Thermo- 

 metric 

 values. 



At the end of — 



1 min. 15 sec. 



2 „ „ 

 4 „ „ 

 6 „ „ 



21-036° 

 42*721 

 74*840 

 99-075 



0'0141S°C. 

 002880 

 0-05045 

 0-06679 



32-445° 

 59-068 

 103-200 

 136-000 



0-02187° C. 

 003982 

 0-06957 

 0*09169 



6-370° 

 19-379 

 32 55S 

 49-612 



0-00429° C. 

 0-01306 

 0-02195 

 0-03344 



