192 Annals of the Philosophical Club 



1873. Feb. 27th, 233rd meeting. Professor Tyndall 

 described his recent visit to the Niagara Falls, stating that 

 he considered the disturbance of the surface in the centre 

 of the Rapids, three miles below the Falls, to be due, not to 

 inequalities of the bottom, but to the meeting of two sets 

 of waves thrown by the rocks on each bank diagonally 

 across the stream. 



June igth, 236th meeting. Dr. Hooker said that a 

 collection of plants, sent by the Challenger from Bermuda, 

 so far as examined, showed the flora of these islands to be 

 closely related to that of the southern United States with a 

 considerable mixture of tropical forms. 1 



Sir B. Brodie described results of his experiments on 

 decomposing carbonic acid gas by induced electricity, in 

 the course of which he had demonstrated ozone to be a 

 triatomic form of oxygen. 



Professor Mayer, 2 of New York (guest), gave an account of 

 his experiments on the elongation of iron bars by magnetism. 



Oct. 30th, 237th meeting. Professor Sylvester exhibited 

 a model of an instrument invented by Captain Peaucellier, 

 of the French Engineers, for converting circular into recti- 

 linear motion. With certain additions, it could also convert 

 spherical into plane motion. By a suitable combination 

 of a number of these, the working point could also be made 

 to describe any algebraical curve up to the sixth order 

 (inclusive). This result he thought might be extended to 

 curves of any degree, and that a connected train of these 

 machines would be capable of reproducing whatever motion 

 could be obtained by any combination of jointed rods. 

 Such a train would serve as a universal calculating machine 

 for extracting the roots of numbers and performing still 

 more recondite algebraical operations, so that he believed 

 Peaucellier's machine would prove to be of the highest 

 practical importance. 



1 The subject was discussed afterwards by Mr. Moseley, of the Challenger, 

 " Notes on the Vegetation of Bermuda," Jour. Linn. Soc. xiv. (Botany), 

 page 317. 



2 Perhaps Dr. A. M. Mayer, Professor of Physics and Director of the 

 Laboratory at the Stevens Institute of Technology, Hoboken, U.S.A. 



