MICROSCOPY. 239 



ment by that of Ross, so far as attractiveness of appearance 

 was concerned, for R. and J. Beck's exhibit was more com- 

 plete, but badly displayed ; Crouch also exhibited a full se- 

 ries of instruments of excellent workmanship and at moder- 

 ate prices. The only American display of any note was by 

 Zentmayer, of Philadelphia. Messrs. Bausch and Lomb, of 

 Rochester, however, exhibited a large series of entirely new 

 designs, elaborated under charge of E. Gundlach, formerly of 

 Germany, and chiefly remarkable for excellent workmanship 

 and high optical qualities at greatly reduced prices. The 

 other American exhibitors were T. H. M'Allister, George 

 Wale, and J. W. Queen and Co. Powell and Lealand, Hart- 

 nack, Zeiss, Spencer, and Tolles were conspicuous by their 

 absence. 



In the American Journal of Microscopy for April, the well- 

 known optician Mr. E. Gundlach describes two new illumi- 

 nating-glasses for the microscope. One is a hemispherical 

 lens, which is connected to the object-slide by a drop of wa- 

 ter or glycerin, and of such thickness that the converging 

 rays from the mirror undergo no refraction at the first or 

 convex surface, but, on emerging from the plane surface, or, 

 better, the glycerin, are powerfully refracted, but almost 

 without aberration, as the centre of the curve is in the op- 

 tical axis of the microscope, and the object itself is very 

 nearly in the centre of curvature. The other is an oblique 

 light-projector, distinguished from the condenser by the fact 

 of the lower surface being plane instead of convex, and par- 

 allel with the upper one. 



In the April number of the Monthly Microscopical Jour- 

 nal, Rev. S. G. Osborne describes a modification of Reade's 

 "kettle-drum" illuminator under the novel name of the 

 "Exhibitor." Like most other devices of this class, the 

 practice and patience required to master it will more than 

 counterbalance its advantages (if, indeed, it really have any) 

 over the simpler and easier modes of illumination. 



In the Monthly Microscopical Journal for August, 1877, 

 Surgeon J. J.Woodward, Brevet Lieut.-Col., U.S.A., describes 

 a simple device for the illumination of balsam-mounted ob- 

 jects for examination with immersion objectives whose "bal- 

 sam angle " is 90 or upwards. A truncated rectangular 

 prism of glass, supported base upwards upon a similar trim- 



