INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 853 



are four vertical pivots d, iiiDon wliich are fitted, so as to turn freely 

 thereon, tlie four flanged rollers D D and D' D'. In front of tlio 

 rollers D is fitted a flat metal plate E, and at the back of the rollers 

 D' is similarly fitted a flat strip of wood F, the side of the strip 

 bearing against the rollers being provided with a lining of india- 

 rubber. The plate E and the strip F are secured together by means 

 of the transverse tie bolt G and the clamp H, thus forming a kind of 

 rectangular frame, capable of traversing freely to and fro on the 

 rollers D and D'. At the end of the stage-plate A is mounted in 

 suitable bearings a crank-shaft I, fitted with a flywheel I* and a 

 winch-handle J. This crank is connected by the rod K to the bolt 

 G of the rectangular frame E F. In front of the plate E are secured 

 the metal bars L and L'. The bar L is slotted, and is secured by 

 two screws, so as to be capable of adjustment vertically by means of 

 the screw I. The bar L' is pivoted to the plate by one screw, so as 

 to admit of adjustment laterally by means of the screw I'. A fine 

 saw web m is clamped by its ends to the two bars L L'. 



The saw being clamped in its place, the requisite tension can be 

 given to it by the screw l', while, by means of the adjusting screw I, 

 its parallelism can be secured. On turning the crank-shaft I by 

 means of the winch-handle J, a reciprocating motion will be imparted 

 to the frame E F and to the saw m. 



For holding and imparting the reqiaisite feed to the material to 

 be cut, the following contrivance is adopted : — Beneath the stage- 

 plate A is secured a tube M (shown detached in longitudinal section 

 at Fig. 79). Sliding freely inside this tube is a solid cylinder N. 

 This cylinder is pressed by a spiral spring against a micrometer 

 screw P. On the upper side of the cylinder N is secured by screws 

 a lever arm Q. This lever arm carries at one end a counterpoise 

 weight E, and is furnished at the other end with a clamp and binding 

 screw S. The material to be cut — say a piece of bone — is fastened 

 by any suitable cement (such as glue) to a slip of wood T, and this 

 slip is clamped, as sliown in the figure, to the end of the lever arm Q. 

 By turning the micrometer screw P the cylinder N will be driven 

 forward, carrying with it the lever arm Q and the piece of bone to be 

 cut. The counterpoise R will now cause the piece of bone to bear 

 upwards against the teeth of the saw, and a rapid rccii)rocating 

 motion being imparted to this latter, as already explained, a thin 

 slice will be cut oil". This operation may be repeated imtil the whole 

 of the material is cut up. The slices can then be removed from the 

 wooden slip by snaking in a little warm water. 



A grooved pulley U is provided on the crank-shaft in order that 

 the machine may be driven by a flywheel and treadle if desired, and 

 saws of different degrees of fineness may be employed to suit the 

 various materials required to bo cut.* 



Bleaching and Washing Sections. f — Mr. S. Marsh, jun., suggests 

 the direct action of free chlurinc for bkaching vegetable tissues prior 



' Son Mourn. Qiiok. Mi( r. ( liil),' vi. (I^SO) p. 8:5. 

 t Ibi'l., i-p. Tit-?. 



