Intelligence and Miscellaneous Articles. SiS 



*t> 



Mr. Lassell that some difficulties had been found in the arrangement 

 of the edge-bearing of the mirror, which had been overcome by sus- 

 pending it in an iron hoop. These, however, from the great differ- 

 ence of dimensions, would probably be trifling compared with those 

 of Lord Rosse's mirrors. 



Adverting again to the mounting of these telescopes, the Astro- 

 nomer Royal suggested for consideration whether it might not be 

 advantageous to mount the telescope with an altitude and azimuth 

 movement, by an overhanging fork inserted in a vertical pillar. If 

 a rod were joined to the stalk of this fork, and, by means of an or- 

 dinary parallel motion, were compelled to move parallel to the axis 

 of the telescope, and if any part of this rod were connected by an- 

 other rod (adjustable in length according to the polar distance of 

 the object) to a universal joint on the ground, in such a position 

 that the line drawn from that universal joint to the stalk of the fork 

 is a polar axis, then the motion of the telescope would be equatoreal. 

 For the observer, it was proposed that an observing-box should be 

 fixed to the telescope, and that the access should be by a spiral 

 staircase round the pillar, by a narrow platform near its top, and 

 by a staircase along the side of the tube. 



In conclusion, the Astronomer Royal observed that it was impos- 

 sible to overrate the advance that had been made in the construction 

 of telescopes by the two amateur constructors of whom he had spoken. 

 Lord Rosse had shown that it was possible, without any important 

 manual labour, to produce with certainty, by means of machinery, 

 mirrors of a size never before attained, and perhaps with a perfect- 

 ness of definition which had not been reached before ; and he had, 

 by publication and by private communication, made these methods 

 accessible to the world. This success was the more remarkable, 

 because the whole of the work was done by workmen found on the 

 spot ; even the steam-engine, by which (to a late time) the whole 

 of the machinery was driven, was made by native workmen under 

 Lord Rosse's personal instructions. To Mr. Lassell also much was 

 due, for the example which he had set of what may be done by a 

 man possessing less ample means, and whose time is fully occupied 

 in business ; and much also for the elegant and compendious and 

 manageable apparatus arranged by him, which promises to be of the 

 greatest use in the construction of large object-glasses as well as of 



LXXIX. Intelligence and Miscellaneous Articles. 



DEFLECri'ION OF THE MAGNETIC NEEDLE BY THE ACT OF 

 VOLITION*. 



THIS curious and interesting experiment is due to the investigations 

 of M. DuBois Reymond of Berlin, and his method of performing 

 it is as follows : — He takes a very sensitive galvanometer, and attaches 

 to the terminal wires thereof two perfectly homogeneous strips of 

 * We are indebted to the kindness of W. G. Lettsom, Esq., for the com- 

 munication of this notice, by whom we are also informed that the experi- 

 ment has been repeated with success. 



