382 PROCEEDINGS OF THE SOCIETY. 



MEETING 



Held on the 18th of May, 1904, at 20 Hanover Square, W. 

 Dr. D. H. Scott, F.R.S., etc., President, in the Chair. 



The Minutes of the Meeting of April 20, 1904, were read and con- 

 firmed, and were signed by the President. 



The List of Donations to the Society, exclusive of exchanges and 

 reprints, received since the last Meeting, was read. 



From 

 Osmond and Stead, Microscopic Analysis of Metals. "I rpj ie p u in s ] iers 



(8vo, London, 1904) .. .. / 



Harriman Alaska Expedition. Vols. VIII., IX., Insects;! T7 p,,/?-.;,.,.. 



Vol. X., Crustacea. (8 vo, New York, 1904) ,. . ./ ine ^wmners. 



A Ladd's Student's Microscope Mr. Wynne E. Baxter. 



An old portable Microscope Dr. C.St. Avbyn Farrer. 



Descriptions of the Microscopes presented to the Society by Mr. 

 W. E. Baxter and Dr. Farrer, contributed by Mr. Rousselet, were read to 

 the Meeting. 



The thanks of the Society were voted to the donors, and to Mr. 

 Rousselet for his communication. 



Mr. F. W. Watson Baker exhibited and described three new devices 

 which had recently been brought out by Messrs. AVatson & Sons. The 

 first of these was a new objective changer, consisting of two rollers linked 

 together, and having a jaw on each The rotation of these rollers by 

 means of a handle caused the inversion of the jaws, leaving a clear open- 

 ing for the insertion of the objective. On releasing the handle, the 

 rollers and jaws were carried back to their previous position by the action 

 of a coil-spring, in doing which the objective threads were gripped and 

 the shoulders brought together. In consequence of the variations in the 

 pitch of the screw-thread used by different makers, it was found necessary, 

 in order to secure accurate working, to supply small rings to fit on the 

 objectives for use in this changer. Two special features were claimed for 

 the changer : one was its thinness, the increase in the length of the body 

 by its use being only ^ in. ; the other its light weight, it being con- 

 structed of magnalram. 



The second item exhibited was a mounting device, designed by 

 Mr. W. Pcosenhain, for microscopic specimens of irregular shape, such 

 as metal sections. The description read to the Meeting was, that for 

 microscopical examination it was necessary to mount metal specimens 

 in such a way as to ensure that the polished face was accurately adapted 

 for the optic axis of the Microscope. This was sometimes secured by 

 the use of a levelling stage, but the device shown consisted of two 



