15G ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



the conditions of the problem, and this can not be said of 

 either of the theories which have thus far been discussed. 

 To quote the eloquent language of Sir Humphrey Davy, 

 " When I consider the variety of theories which may be form- 

 ed on the basis of one or two facts, I am convinced it is the 

 business of the true philosopher to avoid them altogether. 

 It is more laborious to accumulate facts than to reason con- 

 cerning them ; but one good experiment is of more value 

 than the ingenuity of a brain like Newton's." 7 -4, XL VIII., 

 94. . 



THE SPECIFIC HEAT AND CUBIC EXPANSION OF BODIES. 



Mr. Walter Spring communicates to the Royal Academy 

 of Belgium the following note with reference to the specific 

 heat of bodies. He states that he sought to determine 

 whether there were any relation between the specific heats 

 and the co-efficients of cubic expansion by heat. He arrives 

 at very beautiful results, both practically and theoretically. 

 For instance, the computations which he makes of the spe- 

 cific heats of mercury and of graphite agree to the fourth 

 decimal place with the observations of Regnault, Dulong, 

 and Petit. He concludes that the product obtained by mul- 

 tiplying the specific heat of any body by its atomic weight 

 can not be constant, since the specific heat is itself a func- 

 tion of a variable factor. Bulletin of the Royal Academy 

 of Belgium, 1874, 294. 



LIGHTNING-CONDUCTORS. 



In a few remarks upon the action of lightning-conductors, 

 Secchi, the well-known astronomer, describes the storm of 

 November, 1872, in -which the cathedral and palace of Alatri 

 were struck by lightning, these structures having been free 

 from such visitations for many years. The damage done on 

 this occasion was, as he shows, due in great measure to the 

 fact that the lightning-rods, instead of being directly con- 

 nected with the metallic gutters and other portions of the 

 roof, were isolated from them. The fluid, therefore, sought 

 to make its own way to such other good conductors as were 

 near. After quoting other instances, he expressed the opin- 

 ion that the conditions most favorable to safety consist in 

 joining the lightning-rod directly to all the metallic portions 



