62 Royal Society : — 



unit of area at the temperature t and blowing it up again to its 

 original dimensions after hanng raised its temperature to t'. If t'—t 

 be infinitely small, and be denoted by C, the gain of work may be 

 expressed by 



at 

 and by using Camot's principle as modified for the Dynamical 

 Theory, in the usual manner, we find that there must be an absorp- 

 tion of heat at the high temperature, and an evolution of heat at the 

 low temperature ; amounting to quantities differing from one an- 

 other by 



1 -2JT ^ 



and each infinitely nearly equal to the mechanical equivalent of this 

 difference, divided by Camot's function, which is -. if the tempera- 

 ture is measured on our absolute scale. Hence if a film such as a 

 soap-bubble be enlarged, its area being augmented in the ratio of 

 1 to m, it experiences a cooling effect, to an amount calculable by 

 finding the lowering of temperature produced by removing a quan- 

 tity of heat equal to 



t -dT 



from an equal mass of liquid unchanged in form. 



For water T=2'96 gr. per lineal inch. 



Work per square inch spent in drawing out a film =5'92, say 



6 grains, -r-=r^T, or thereabouts. 

 at ooU 

 ft 300 

 Suppose -^ss- „ — Yo' ^^^^ the quantity of heat to be removed, 



to produce the cooling eifect, per square inch of surface of augmen- 

 tation of film will be -tVo • Suppose, then, 1 grain of water to be 

 drawn out to a film of 1 6 square inches, the cooling effect will be 

 ifi^ of a degree Centigrade, or about ^4^. The work spent 

 in drawing it out is 16 X 6=96 grains and is equivalent to a 



96 1 



heatina; effect of -— — r7r?rF;=r=r7. Hence the total energy (reck- 

 ° 12x1390 1/4 *=•' "^ 



oned in heat) of the matter is increased yfj- + -^ of a degree Cen- 

 tigrade, when it is drawn out to 1 6 square inches. 



" On the Logocvchc Curve, and the geometrical origin of Loga- 

 rithms." By the Rev. J. Booth, LL.D., F.R.S. 



June 17. — The Lord Wrottesley, President, in the Chair. 



The following communications were read : — 

 " Description of some Remains of a Gigantic Land-Lizard (Mega- 

 laniapriaca, Ow,) from Australia." By Prof. Richard Owen, F.R.S. 



