128 Progress in Science. (January, 
given out that wave of motion, and arein a condition to absorb heat from the 
tissues. That the ability of the nerve to perform its function depends on 
absorption of heat from the surrounding tissues is a supposition confirmed by 
the fac that, if you reduce the temperature greatly, the nerve ceases to ad. 
Professor CLERK MAxwELL—No doubt there is plenty of power in the 
heat of the body to renovate a nerve. But as heat can do work only by 
passing from a hotter body to a colder, ‘‘all the king’s horses and all the 
king’s men” could not renovate the nerve by the aid of heat alone. 
At the late British Association Meeting at Belfast an important communi- 
cation ‘On the Absolute Electro-Magnetic Units of Resistance and Elec¢tro- 
Motive Force, with Suggestions for their Re-determination,” was made to 
Section A by Prof. G. Carey Foster. The method consists in determining the 
ratio of the ele&romotive force to the strength of the current produced by it 
in a given conductor; and then, since— 
E 
awe 
the resistance of the condudor is determined. For this purpose a large coil 
of covered copper wire, like a hoop placed vertically, is made to rotate about 
a vertical axis, so as to have a certain electromotive force E generated in it by 
Hi 
J 
the horizontal component of the earth’s magnetic force. During each half- 
revolution beginning and ending with the plane of the coil at right angles to 
the magnetic meridian, the mean value of E is— 
Bae 
t 
where a is the effective area of the coil, ¢ its time of revolution, and H the 
earth’s horizontal intensity ; but during successive half-revolutions the sign of 
