INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 329 



Beck's Improved Microscope-Stand with swinging Substage 

 (Plate IX.). — The Stand has a tripod A for its base, ujjon which is 

 placed a revolving fitting B, graduated to degrees, so that the 

 Microscope can be turned round without being lifted from the table, 

 and the amount of rotation registered ; upon this fitting are two 

 pillars and between them the limb C can be elevated or depressed 

 to any angle, and tightened in its position by the lever D. The limb 

 carries at one end the body E, with binocular jjrism I, and coarse 

 (K) and fine (L) adjustments ; in its centre is the compound stage F, 

 beneath which is the circular plate J, carrying the swinging bar 

 U with the substage G, and at the lower end of the limb is another 

 triangular bar V carrying the mirror H. 



The compound Stage is of a new construction. It is attached 

 to the limb on a pivot, and can be rotated so as to be set at any 

 inclination, the angle being recorded on the divided plate E, or it 

 can be turned completely over, so that the object is then underneath 

 and can be viewed by light of any obliquity witliout interference from 

 the thickness of the stage. It revolves in a circular ring by the 

 milled head P, or this can be drawn out, and then it turns rajiidly 

 by merely applying the fingers to the two ivory studs Q Q fastened 

 on the top plate, which is divided into degrees to register the amount 

 of revolution. M is the usual spring-piece for clamping the object, 

 and N, the milled heads of the rectangular movements. Beneath 

 and attached to the stage is an iris diaphragm S, which can be 

 altogether removed from its dovetailed fitting, so as not to interfere 

 during the rotation of the stage. The variations in the aperture 

 of this diaphragm are made by a pinion working into a racked arc 

 and adjusted by the milled licad T. 



Of the two triangular bars beneath the stage, V is rigid in the 

 optical axis of the instrument, the other, U, swings to either side 

 and carries the Substarje G which is racked up and down by the 

 milled head W. The bar U is attached to an arc J working in 

 the circular fitting Y, and is revolved by a rack and pinion X, the 

 amount of angular movement being recorded on the ujiper surface of 

 the plate. This allows of illumination being used at any angle beneuth 

 the stage, or if desired the bar U can be carried round and above 

 the stage for opaque illumination. Having once fixed the angular 

 direction of the light, the focussing of it is eftected by the lever Z, 

 which moves the circles J, Y up and down, on a dovetailed fitting, 

 and with them the arm U (carrying the illuminating apparatus) in 

 the ojitical axis of the inatriimcnt, the amount of the elevation and 

 depression being registered on a scale attaclied to the limb. 



The Mirror II is carried on the bar V when the illumination 

 is required to be concentric with the optical axis of the Microsco])e, 

 and iuflepcndent of the movements of other illuminating apparatus ; 

 when desired, however, it slides on U, and can then be moved below 

 or above tlie stage in tlie same way as the substage. It revolves on 

 a circular fitting for giving greater facilities in regulating tlie direc- 

 tion of the reflected l)eam, and is made to reverse in the socket so as 

 to bring the centre of the mirror concentric with the axis of the 

 instrument in either case. 



