TRANSACTIONS OF THE SECTIONS. 



29 



change of elasticity produced by extremes of temperature in the sus- 

 pension-spring ; and 3rd, because another quantity is due to that effect 

 of extreme cold which is indicated by a decrease in the vibration-arc 

 of the pendulum. In the present case, the reduction of compensation 

 required is so small, that until some cause for stopping the clock occurs, 

 Professor Johnson is not anxious that the compensation shall be at- 

 tempted. 



The following is the monthly abstract of the mean daily rate of the 

 transit-clock, as observed by the late Savilian Professor of Astronomy : 



Mean Daily Rate, 

 sec. 



1838, October -0-136 . . 



„ November — 0'51 1 . . 



„ December — 0'987 . . 



1839, January —0-887 . . 



„ February —0*544 . . 



„ March —0-414 . . 



„ April -0-060 . . 



„ May -1-0-016 . . 



„ June +0*222.. 



„ July -1-0-375 .. 



„ August -f-0*223 .. 



Therm. 



o 



50*14 

 44-18 

 41-47 

 38*45 

 42-29 

 41-18 

 55*57 

 55-38 

 62-57 

 65*00 

 64-53 



On Natural Perspective. By Mr. Parsey. 



On an analogy between the atomic weights of certain Gases and the ex- 

 pansions of the primitive colours of the Solar Spectrum. By Lieut. 

 Morrison, R.N. 



CHEMISTRY. 



On the Theory of the Voltaic Circle. By Prof. Graham. 



Professor Graham explained the views now received of the propa- 

 gation of electrical induction through the fluid and solid elements of 

 the voltaic circle, by the formation of chains of polar molecules, each 

 of which has a positive and negative side, and in which no circulation 

 of the electricities is supposed, but merely their displacement and se- 

 paration from each other in each polar molecule. These electricities 



