148 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



THE ELECTRICAL RESISTANCE OF SELENIUM. 



The question having been raised as to whether the phe- 

 nomena observed by Mr. Willoughby Smith, as to the effect 

 of li^ht on the electrical resistance of selenium, could not be 

 more properly explained, as the effect of heat, and whether 

 the selenium might not replace the thermal pile in the meas- 

 urement of radiant heat, the Earl of Rosse has made an in- 

 vestigation ; whence he concludes that we must give up all 

 hope of selenium replacing the thermal pile, although he has 

 nothing to say either in favor of or opposed to its applica- 

 bility to photometric purposes. Selenium is, he finds, in fact, 

 absolutely insensible to radiant heat of low refrangibility, 

 and on two occasions he notices a diminution of the electric 

 resistance after a certain duration of exposure to and screen- 

 ing from light. 7 A, XLVIL, 161. 



THE CALORIFIC EFFECTS OF OPPOSING MAGNETISMS. 



Cazin states that he has observed the calorific effects which 

 accompany the disappearance of magnetism in the core of a 

 rectilinear magnet which has several consequent points, and 

 has arrived at the following law, namely : When a rectilinear 

 core of iron is magnetized by a series of identical coils through 

 which the current passes in alternately opposite directions, 

 if the coils determine equal concamerations, then the quanti- 

 ties of heat produced in the core by the disappearance of 

 magnetism are inversely proportional to the squares of the 

 numbers of concamerations. The experimental results ar- 

 rived at by means of his delicate apparatus conform to the 

 law of magnetic energy, which he communicated nearly two 

 years ago, and the apparatus is sufficiently delicate to justify 

 him in hoping that he will be able to determine the magnetic 

 equivale.it of heat. 7 A, XLVIL, 392. 



ARCHIBALD SMITH. 



The death of Archibald Smith, on the 2Gth of December, 

 1872, has been followed by an obituary notice published in 

 the Proceedings of the Royal Society for February, 1874, 

 from which is here obtained a connected view of the very 

 important researches which form his main contribution to 

 science : viz., his study into the phenomena of ships' magnet- 



