237 



character from the voltaic, the difference of the force from which it 

 proceeds; mechanical power acting by intermitting pressure. This 

 force also, through the medium of the magnet, produces a similar 

 effect ; and heat when applied to crystalline or metallic bodies, 

 originates peculiar electric phenomena. Doubtless similar results 

 will also be discovered to proceed from the action of capillary attrac- 

 tion, the disintegration of solids, or the change of density in fluids. 

 Many of these it is probable are concerned in producing the elec- 

 troscopic phenomena observed in the voltaic circuit, which are by no 

 means necessarily connected with the true current ; and therefore in- 

 dependent of mere controversy, it is important that they should be 

 carefully observed and measured. In Mr. Dale's hands we have not 

 only every reason to beUeve that this will be effectually performed, 

 but that he will also advance and improve the means of making this 

 class of observations which at no distant date must play an important 

 part in molecular physics. 



As to Prof. Williamson's grant for investigating the law of the 

 -chemical action of masses, Berthollet carried this to an extreme, 

 believing that in every case mass was as important as affinity, so that 

 the strongest force of the latter would be compensated by a larger 

 amount of the former acting by a very weak chemical attraction. 

 This was quite at variance with any theory of definite proportions, 

 and he explained the multitude of instances which seemed to enforce 

 that theory by the influence of cohesion, crystallization, and other 

 molecular forces. This view, though ingenious and containing some 

 truth, has been thrown into the shade by the triumph of the other ; 

 but Mr. Williamson believes that he has found in the class of com- 

 pounds represented by sulphovinic acid, a means of measuring the 

 influence of quantity. 



This year a grant has been made, to the same amount as last year, 

 to defray the expense of drawings of interest, to be executed under 

 the direction of Professor Owen : the valuable result of the previous 

 grant, by which a series of beautiful drawings of the skeleton of the 

 Megatherium in the British Museum were obtained, make it desirable 

 that you should continue to profit, in the same way, by his 

 powers and genius. 



As to the grants of former years, where the investigations are in- 

 complete, satisfactory reports have been received as to the progress 

 made ; where complete there is every reason to be satisfied with the 

 results. Among the latter are Mr. Cooper's Catalogue of 14,888 

 ecliptic stars. It is a most valuable addition to Astronomy, going 

 down to stars of a magnitude far below that which were previously 

 observed ; the limit being those visible in the unilluminated field of 

 an achromatic of inches aperture. In the Introduction to this 

 work the mode of observation is detailed, and the limits of error 

 within which the places may be affected for a single observation is 

 l"-3 or about 6" in space; but as many of them have been thirty 

 times observed, and most of them from fifteen to twenty times, the 

 probable error of the places given in the Cataiogue may be taken at 

 • 2". When the maps he is constructing from this Catalogue are 



