12 Dr. J. S. Lombard. On the Propagation of [Nov. 17, 



adhesion between the bone and the pile had taken place. The whole 

 pile, and the bone, to within a couple of millimetres of its free surface, 

 was then wrapped in thick layers of cotton wool soaked in melted 

 paraffine, these layers extending beyond the upper end of the pile and 

 along the conducting wires for a little distance. In the cases of brain- 

 tissue and skin, a pasteboard box was taken and filled with melted 

 paraffine. When the latter had solidified, a hole was cut through the 

 centre of the paraffine of the size of the piece of brain or skin, and 

 the pasteboard bottom corresponding to the hole removed, and its 

 place supplied by a thin copper plate. The piece of tissue was then 

 inserted in the hole in the paraffine, until it rested on the copper 

 plate ; the pile was then passed into the hole and pressed firmly upon 

 the piece of brain or skin, being kept in place by wedges of cotton 

 wool thrust between the sides of the pile and the paraffine walls sur- 

 rounding it. 



The free end of the bone, or the copper plate of the box,* was 

 brought in contact with water of the desired temperature, this tem- 

 perature being tested by both thermo-electric apparatus and thermo- 

 meters. 



The differences of temperature to which the tissues were subjected 

 ranged from 0°"1136 C. to 0°'1645 C. 



We have to consider, first, the time required for the first sign of the 

 change of temperature to show itself through the pieces of bone, brain, 

 and skin. The following figures show the times required for o, l C. 

 to show itself through 7'5 millims. of sheep's skull, 7"5 millims. of 

 upper surface of sheep's cerebrum, and 3 millims. of sheep's scalp 

 respectively. 



The galvanometer shows 0°'0006742 C.— 





Bone. 



Brain. 



Scalp. 



37 -30 seconds. 

 55 -86 „ 

 26 -29 „ 



40 490 seconds. 

 63 -706 „ 

 27 -646 „ 



22 -880 seconds. 

 29 -417 „ 



10 -ooo „ 



We have next to consider the degree of change of temperature pro- 

 duced by conduction, at certain measured intervals of time, through 

 the same thicknesses of tissues as above, and calculated for 0'1° C, 

 with the galvanometer showing, as before, 0° '0006742 C. The 

 averages alone are given. 



* It was found, by many experiments, that the presence of the copper plate could 

 be disregarded. The same is true of the dura mater in the case of brain-tissue. 



