1835.] the Advancement of Science, 216 



4th. The action of several electro-magnets without their 

 interfering with each other. 



17. Mr. R. W. Fox on a new dipping needle. The instru- 

 ment which shews, at once, the dip, intensity, and variation, 

 was exhibited. It contains graduated circles, moving in 

 altitude and azimuth, and a vertical index adjusted to meri- 

 dian, turning in azimuth till the needle is vertical. Hence, 

 the dip may be deduced, and the intensity, by comparing 

 the effect of a small magnet introduced. 



Professors Stevelly and Lloyd made some remarks. 

 The accuracy of the instrument was confirmed by the 

 testimony of Sir John Franklin, who had examined it in 

 connexion with Messrs. Christie and Barlow, even under 

 extreme conditions. 



18. Professor Hamilton on the theory of Logologues, and 

 other numbers of higher orders. He discussed the nature of 

 algebra, and whether it is to be considered a science or only 

 a language? His leading idea is, that it may be regarded 

 as the science of pure and abstract time, as geometry is the 

 science of pure space ; and that the distinction of positive 

 and negative corresponds to past and future. He regards 

 imaginary quantities as couples of moments, or couples of 

 steps : a given moment as having a given position, in regard 

 to time, as a given point in space : each step has direction 

 and magnitude. He referred to his paper in the Irish Trans- 

 actions, which contained his suggestions for certain improve- 

 ments and simplifications in algebra. 



Thursday, 13/A August. — Mr. R. Roberts exhibited an 

 apparatus by which figures may be seen, or sentences read, 

 as distinctly, when revolving at a high velocity, as when in 

 a state of quiescence. It illustrates, also, the duration of 

 light on the eye. 



19. Mr. Baily read his report on the Aberdeen Standard 

 scale of 3 feet, which was compared with that of the Astro- 

 nomical Society, by the recommendation of the Association. 

 He found a small difference, and concluded with some 

 suggestions for the better construction of such scales. 



Sir Thomas Brisbane remarked the necessity of attending 

 to expansion. Professor Stevelly made some observations 

 on the same point, to which Mr. Baily replied, by stating 

 the precautions which had been used. 



