CONSTRUCTION OF THE MICROSCOPE. 47 



well as behind. Hence the Author regards the arrangement adapted by 

 Messrs. Siebert and Kraft (Fig. 33) as preferable ; in which the supports 

 for the hands are oblique wooden blocks, altogether disconnected from 

 the stage. These, being hinged to the wooden base of the pillar, can be 

 made to turn up for portability (as shown in Fig. 34), so that the instru- 

 ment packs into a very small compass. 



46. Laboratory Dissecting Microscope. Where, on the other hand, 

 portability may be altogether sacrificed, and the instrument is to be 

 adapted to the making of large dissections under a low magnifying power, 

 some such form as is represented in Fig. 35 constructed by Messrs. Baker 

 on the basis of that devised by Prof. Huxley for the use of his Practical 

 Class at South Kensington will be found decidedly preferable. The 

 framework of the instrument is solidly constructed in mahogany, all its 

 surfaces being blackened; and is so arranged as to give two uprights for 

 the support of the stage, and two oblique rests for the hands. Close to- 



Laboratory Dissecting Microscope. 



the summit of each of these uprights is a groove into which the stage-plate 

 slides; and this may be either a square of moderately thick glass, or a plate 

 of ebonito having a central perforation into which a disk of the same 

 material maybe fitted so as to lie flush with its surface; one of those being 

 readily substituted for the other, as may best suit the use to be made of it. 

 The magnifier is carried on an arm working on a racked stem, which is 

 raised or lowered by a milled-head pinion attached to a pillar at the fur- 

 ther right-hand corner of the stage. The length of the rack is sufficient 

 to allow the arm to be adjusted to any focal distance between 2 inches and 

 l-4th of an inch. But as the height of the pillar is not sufficient to allow 

 the use of a lens of 3 inches focus (which is very useful for large dissections) 

 the arm carrying the lenses is made with a double bend, which, when its 

 position is reversed (as is readily done by unscrewing the milled-head that 

 attaches it to the top of the racked stem), gives the additional inch 

 required. As in the Quekett Microscope, a Compound body may be easily 

 fitted, if desired, to a separate arm capable of being pivoted on the same 

 stem. The mirror frame is fixed to the wooden basis of the instrument; 

 and places for the magnifiers are made in grooves beneath the hand- 



