CA.yADlA> T INSTITUTE. 



315 



Afterwards the furnace wails are removed. The entire mass is then fractured, the 

 manner of doing this is a secret with the manufacturer;!; but it is accomplished in 

 such a way that every piee? is homogeneous in refractive power. The pieces are 

 next softened by heat and pressed into moulds, giving disks of different sizes. The 

 telescope-makers purchase these and grind them into the required thickness and lens 

 form. Two separate disks, one of crown, and the other of flint glass, are necessary 

 to form an object glass. One of these is concave, the other convex. It is by the 

 union of the two that the object glass is made achromatic. The grinding is a slow 

 and most difficult process as the utmost exactitude must be attained. First the edge 

 is ground to enable the maker to see whether the glass is clear and without air bub- 

 bles. It not unfrequently happens that many disks have to be rejected. When a 

 very superior glass is finished, it is of great value. The twelve-inch of the Cincin- 

 nati Observatory alone cost $6,000. — Chicago Journal. 



CANADIAN INSTITUTE 



session 1855-56. 

 fourth ORDINARY MKETISG — Saturday, 19th January, 1856. 

 Professor Bovell, M. D., Vice President, in the Chair. 

 The following gentlemen were elected Members : 

 Viscount Bury, Toronto. 

 Alfred Roach, Esq., Toronto. 

 George Desbarats, Esq., Toronto. 

 Capt. Alexander Cree Meik, Toronto. 

 John Shaw, Esq., Toronto. 

 James Fisxin, Esq,, Toronto. 



Junior Members : 

 Mr. Clarence Moherly, Toronto, 

 Mr. C. W. Patterson, Toronto. 

 Oa the motion of Professor Wilson, seconded bySanfoid Fleming, Esq., it was 

 resolved : 



That the Canadian Institute knowing the pers< nd valuable efforts which 



have been made by its first President, W. E. Logan, Esq., to bnr^g the Geological 

 resources of the country prominently forward, and observing with much satisfac- 

 tion the honorable position in which Canada has been placed in England, and more 

 recently in Paris, in a great measure through hi? endeavors: it is the opinion of 

 this Institute that some acsnowledgment of Mr Logan's" valuable services is richly 

 due to him — and with that • ■ the following gentlemen consti- 



tute a Special Committee to report at the nesi meeting, on the best manner in 

 which the object should be carried out: — Messrs. ; t. W. Allan, F. W. Cumber- 

 land, and S. Fleming. 



The donation was announced from the Hon. J. M Brddhead, Washington, of 

 the "United States Astronomical Expedition," vols. 1 and 2, quarto; and the 

 thaDks of the Institute were vcted to the Donor. 



The folio 



1. By the Rev. Pi M. A., " E 



Theory of Knowing and Being." 



