854 SUMMARY OF CURRENT RESEARCHES RELATING TO 



MICROSCOPY. 

 a. Instruments, Accessories, &c.* 



Del)y's Twin Microscope. — Mr. J. Deby, C.E., sends us the 

 following description of a new selecting and mounting Microscope 

 devised by him : — 



" Being myself in tbe position of many other lovers of the Micro- 

 scope in regard to the few occasional hours I can find time to spare 

 for its enjoyable employment, I hope I may be rendering a service 

 to some of my fellow-workers by publishing the description of a 

 labour-saving selecting and mounting instrument which I recently 

 designed for the purpose of making the most of my time, and which 

 has been most carefully constructed for me by Messrs. Beck. 



The Microscope, which I propose to call the " Twin Microscope," 

 consists of the following parts (fig. 180) : — 



1. Two independent parallel tubes attached to the same stage ; 

 the axis of each of the tubes corresponding to the centre of one of the 

 eyes of the observer. Each tube has its independent rack motion by 

 a milled head. 



2. Two mirrors, one for each tube, with swinging bars and usual 

 motions. 



3. A fixed stage of large size,with necessary clamps for holding two 

 parallel glass slides, one under each of the tubes. 



4. A movable substage, placed immediately below the upper stage, 

 having a considerable range of rectangular mechanical motions by 

 means of two milled heads. 



5. A mechanical finger attached anteriorly to the movable sub- 

 stage. This finger is provided with universal motions by a ball-and- 

 socket arrangement. It is suited for carrying a bristle-holder, 

 needle-holder, or small scalpel. A small milled head permits of the 

 rotation of these holders independently of the ball and socket which 

 holds them. 



6. Eye-pieces and objectives, either similar or dissimilar, for both 

 the tubes. 



The directions for the use of the instrument may be summed up 

 as follows : — 



a. Clamp a slide with the material to be operated upon under, one 

 of the tubes, and clamp another clean slide under the other tube. 



h. Dissect or pick-up the desired object from slide No. 1 by using 

 one eye only, that over tube No. 1. 



c. Close this eye and open the other, looking down the tube 

 No. 2. 



d. Swing the object rapidly round by means of the mechanical 

 finger till it appears under the other eye. 



* This subdivision is arranged in the following order : — (1) Stands ; (2) Eye- 

 pieces and Objectives ; (3) Illuminating Apparatus ; (4) Other Accessories : 

 (5) Photo-micrography ; (6) Manipulation ; (7) Microscopical Optics, Books, 

 and Miscellaneous matters. 



