80 Dr. Butherford's Freezing Microtome. By W. J. Fleming. 
this purpose was the Stirling section-cutter surrounded by a 
freezing mixture contrived by Dr. Eutherford, and described in 
the * Lancet' in 1873, vol. ii., p. 108. The objection to it is its 
cumbrousness and the difficulty which its size adds to the necessary 
manipulations. This same fault entails that the whole machine be 
firmly fixed^ — an arrangement which, in my opinion, very much 
reduces the value of any section-cutter, as it deprives the operator 
of the great assistance to be derived from the movement of the sec- 
tion upon the razor. It often occurs in practice that, if an imbedded 
object is held in the left hand, valuable assistance in making fine 
sections can be derived from slight movements of rotation, elevation, 
or depression, given to overcome some hitch which is noticed in the 
cutting of the razor edge. If the object to be cut is fixed, this 
power is of course lost. These considerations have led me to devise 
the instrament figured here. 
The principle adopted is to freeze the substance in a Stirling's 
section-cutter by causing fluid, reduced to a low temperature, to 
flow round it. The mechanical means by which this is efi'ected 
will be easily understood by reference to the accompanying section. 
Fig. 1. 
Scale one-third actual size. 
Fig. 1. — A, Cylinder of ordinary Stirling's section-cutter, a a, Plate of ditto. 
6, Handle of brass and iron covered with vulcanite, c, Brass chamber sur- 
rounding A entered at top and bottom by two tubes, d and e. /, Movable bottom 
plate (Fig. 2, plan of this plate), which, when the nuts h h are screwed up, fits 
water-tight by the aid of two india-rubber rings sunk in grooves {gg, q g). 
k, One of the two legs forming with the handle a tripod stand. Beat to 
rest upon table or block when in use. 
The manner of employing it is as follows : The substance to be 
cut is placed in the cyhnder, about half an inch from the top, im- 
bedded in scraped potato, muscle, brain-substance, or other suitable 
material. The tube e is connected by an india-rubber tube with 
a worm of block tin immersed in a freezing mixture, and placed a 
few inches higher than the section-cutter. The other end of the 
