352 THE AMERICAN MONTHLY [Nov., 



graphic purposes ; and Naegeli and Schwendener, seem of the 

 same opinion. 



For years I used a condenser I made myself. It cost me 

 nothing, as I had the apparatus, but would only have cost me 

 a very few shillings if I had needed to buy it. 



A small microscope is sold at about the price of Is. Standing 

 on three legs, and containing two good large biconvex glasses, 

 the body screws out of the rim of the stand, and if wrapped 

 round with two thicknesses of chamois leather will tightly fit 

 the understage ring tube. I then got two small biconvex glasses 

 out of an old three-power hand magnifier, and cut the horn 

 rims so that they fitted the aperture of the stage tightly, the 

 smaller lens being uppermost. I then arranged the large lenses 

 so as to get a focus on the surface of a thin slide — that is, the 

 smaller lenses being in place — and the thing was complete. It 

 served its purpose perfectly, as far as my requirements were 

 concerned, and gave me sufficient light on the dullest day of 

 winter to use a water-immersion 1-16. The large lenses were 

 kept in position by rings of stiff paste-board ; room was left 

 above the uppermost lens so that the diaphragm might just 

 clear. I believe I could do anything with the objectives I em- 

 ployed in the way of resolving markings that they were capa- 

 ble of, though I did not go much in for that perhaps somewhat 

 overdone thing. I could get a very complete removal of the 

 former picture when examining tinted bacteria — my usual work; 

 but, of course, the aperture of my condenser had to be greatly 

 cut down to see podura markings, or blood corpuscles, or histo- 

 logical details, even with a l-16in. Lancastrian". — Eng. Mech. 



A New Microscope for Observations at High Tempera- 

 ture. — With a view to examining the transformation of dimor- 

 phous substances at temperatures up to 600°, Mr. Von Wyron- 

 bofif has had constructed a polarization microscope, by Nachet, 

 which is much simpler than the instrument previousl}' em- 

 ployed by Lehmann and others, but which nevertheless, with- 

 stands the radiations of the heated objects for a longer period. 

 These advantages are obtained by giving the objective a very 

 long focus. The polarizing nicol is placed at an adequate dis- 

 tance above the stage. The image is obhquely thrown upwards, 

 and the microscope is suitably bent, whereby the observation 

 can be made in the usual position. The object lies on a per- 



