Mathematical and Physical Science. 363 



summer, and found the maximum to be at 9 a.m., the mean 

 at 3 P.M., and the minimum at 9 P.M. M. KupfFer had ob- 

 tained results of the same general character, so that we may 

 thus apply to observations a correction for the hour of the 

 day. Now, he (Professor Phillips) had found as the result 

 of his observations regarding the point he had in view, that 

 the isoclinal curve in individual cases, and within a limited 

 track, tends towards the high ground. Whenever we come 

 to a mountain country, there we come to great flexures. 



Professor Airey, the Astronomer Royal, laid before the 

 Section a question of Probabilities which had occurred to him 

 in the use of a fixed collimator for the verification of the con- 

 stancy of position of an azimuth circle. 



Mr Nasmyth made an interesting communication on the 

 lunar surface. 



James Dennison, Esq., read a notice on a Tissue spun by 

 Caterpillars. Specimens were exhibited, one a veil, 46 by 

 24 inches, seeming almost to realize the figurative epithet of 

 the ancient " textilis ventus,''' and another, a picture drawn on 

 a portion of a similar tissue, 7 by 5 inches. 



Sir David Brewster shewed to the meeting the beautiful 

 Talbotypes by Messrs Adamson and D. O. Hill, Ross, and 

 Thomson, Edinburgh. 



The Rev. J. B. Reade made a communication regarding a 

 new Solid Eye-piece. 



Sir William Rowan Hamilton read a paper on " Polygons 

 inscribed on a Surface of the Second Order,'* which will ap- 

 pear in the Mathematical Journal. 



Professor W. Thomson read a paper on the Theory of 

 Magnetic Induction. 



Professor Nichol made a communication on the winds in 

 the west of Scotland, as observed at the Glasgow Obsei'va- 

 tory by Mr Osier's Anemometer, giving the reduction of 

 observations for six years in a tabular form. 



Professor Smyth read a paper on Oometary Physics. The 

 motions bad been reduced to mathematical calculation, but 

 the addition to, and arrangement of, the facts regarding 

 comets which observation furnishes, have been too little 

 attended to. Having had an opportunity of seeing a num- 



