70 THE AMERICAN MONTHLY [Mch 



between two projecting arms. Accordingly on compress- 

 ing the arms the jaw leaves a space of about a quarter 

 of an inch between it and the above ring. Each objec- 

 tive is fitted with another steel ring only a little larger 

 in diameter than the milled head of the objective. The 

 objective, instead of being screwed into place as usual, is 

 then simply slipped into position beneath the body tube 

 of the microscope, and is there securely gripped by the 

 semi-circular jaw. As the ring on the objective is made 

 to fit accurately into a recess in the ring that is screwed 

 into the body tube, the objective itself is well centred, 

 though it might possibly be not quite satisfactory for the 

 highest powers. Those who prefer this type of objective 

 changer to the ordinary rotating nose-piece will find this 

 simple little device useful. It is made by R. Fuess, Steg- 

 litz, near Berlin. Its price, with four adapters,is only $4.00. 

 Crouch's "Histologist" Microscope. — Mr. H. Crouch, 

 of 22 Duncombe Road, London, N., has submitted the 

 latest model of his "Histologist"' microscope, which is 

 specially designed for the use of students, particularly 

 medical students. The coarse adjustment is by the now 

 customary diagonal rack and pinion, and the fine ajust- 

 ment is of the micrometer screw type. The foot is a 

 claw-tripod, and as such is perfectly steady. The stage 

 is of the horseshoe pattern, but in the microscope sub- 

 mitted to us the advantage of this was somewhat discount- 

 ed by the sub-stage ring being fixed in position beneath 

 the stage. The microscope itself is well made and finish- 

 ed, and is specially designed to withstand the rough wear 

 and tear of a laboratory. There are the usual plane and 

 concave mirrors. The objectives generally supplied are 

 the f-inch, N. A. -28, and £-inch, N. A. -65, both being 

 arranged to work approximately in the same focal plane. 

 The apertures are moderate, as is suitable for histological 

 work ; but the objectives are excellent ones, and will bear 

 favorable comparison with any others in the market at 



