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PROCEEDINGS OF SOCIETIES. 



the bed, and 3^ inches deep, bevelled at its sides, and having a short 

 tongue, or elongation, at the lower edge, for insertion into either 

 of the dovetailed sockets ; it has a large central aperture, and is 

 provided with a light cross-piece, fitting on the bevelled sides of 

 the stage, and capable of moving easily up or down, for carrying 

 the object-slides ; at the right-hand corner of the stage there is also 

 a small aperture, with a saw cut through its edge, for the reception 

 of the pin of a pair of forceps. The small condenser may also be 

 inserted below the stage into this aperture, so as to condense the 

 rays from the source of light to the mirror, or between the mirror 

 and the stage. 



The clamp, or saddle, should be made as small and as light as 

 is compatible with the thickness of the wooden bed, or stand, and 

 the weight which the screws have to maintain firm and steady. 

 The body is constructed of two tubes sliding the one within the 

 other, so as to allow of its elongation to its proper length when in 

 use. The outer one of these is embraced by a short tube two inches 

 long, lined with cloth, and through which the body tube should 

 have a steady and easy motion, as that forms the coarse adjustment. 

 To the lower edge of this tubular support is soldered the cradle- 

 joint with its attached rod ; the latter being five inches in length. 

 The fine adjustment, which I believe is new, is situated just above 

 the object-glass ; it is constructed on the principle of a common 

 union-joint, the outer half of which works in a male screw at the 



extremity of the body-tube, and acts 

 against a spring in order to maintain a 

 constant bearing, thus : — A is the lower 

 part of the body-tube, having a ring of 

 metal as a stop in its interior, at 1, 

 against which the spring, 3, bears, and 

 liaving a screw on its exterior, at the 

 lower aperture, for the half-union, C, 

 to work in. B is the tube which re- 

 ceives the object-glass at its lower 

 aperture, and has a ring of metal at- 

 tached to its upper extremity, within 

 the body-tube, at a, for the bearing of 

 the lower coil of the spring, 3 ; it has 

 also a slight projection on its exterior, 

 near the object-glass, which is embraced 

 by the curved extremity of the half-union, C. 



The great object in this arrangement was to avoid the projection 

 of a screw-head, which in packing away the instrument generally 

 takes up so much space. By these modifications the whole instru- 

 ment, together with a live-box, two object-glasses, the condensing 

 lens, and the forceps, enclosed in a leather case, occupies a space 

 of 8 inches long, by 3 wide and 3 deep ; so that it can be easily 

 carried in the coat-pocket. The cost is estimated at about £3 for 

 the microscope complete, including the packing-case, without the 

 powers ; or with two French achromatics, at 15*. additional. 



