Year: 1887

page_text: Date of Application, 14th July, 1887
Specification Accepted, 6th Sept., 1887.
I, HENRY FRANK DALE, F.R.M.S. Sutgrove, Cirencester, Gentleman, do hereby
declare the nature of this invention and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement :-
My Invention has reference to the class of instruments known as microtomes,
employed for cutting extremely thin slices or lamina or exfoliations of various
substances, for microscopic observation. The primary object I have in view being to
provide an instrument which, while it may be made at comparatively small cost, shall
be effective and durable to the highest degree possible and which particularly
distinguishes itself also owing to the facility with and advantageous manner in which
it is operated. In order to allow of my invention being the better understood, I have
appended the accompanying two sheets of drawings in which Figure 1. is a sectional
elevation, illustrating the arrangement of the mechanism. Figures 2 and 3 are end
elevations of the same. Like letters of reference being used to denote corresponding
parts in the several figures.
The device in accordance with my invention comprises a table or base plate A,
upon the surface of which is fixed a rectangular box B, having accurately fitted
therein a receptacle a. for the freezing medium or Agent, which latter may be ice, or
equivalent means of producing extreme cold. The receptacle a, (hereinafter termed
the freezing chamber is perforated at the bottom with two holes into the larger of
which is secured a tube b. which contains the object from which it is desired to obtain
a thin section, slice or film. The smaller of the two perforations above referred to,
is provided with a short length of tube c, which serves to drain or carry off the
liquified refrigerant. On the top of the box B. and freezing chamber a is secured,
preferably by screws or equivalents, a face plate C. partially covering said box B.
and chamber a, the open portion 6' thereof being provided to allow of the introduction
of the refrigerant. Said face plate or cover C. is accurately planed so as to present
a perfectly flat and level surface to allow of the cutting knife riding smoothly
thereon; it is also drilled or otherwise perforated to receive the upper extremity of
the tube b. aforesaid to which it is securely attached by brazing or otherwise.
The mechanism for raising the object from which a sectional slice or film is to be
cut, is arranged beneath the base plate or table A above described, and comprises a

page_text: spindle D, upon or near the centre of which is securely fixed a ratchet wheel E. into
the teeth of which latter takes a pawl e. carried upon an arm d, said pawl e. being
pressed against the ratchet wheel E. by a small bent spring f. The arm d. aforesaid
which works loosely upon the spindle Ď is kept in its proper position by means of the
washer g. pinned to said spindle D as shown at g¹; the extremity of said arm d. is
forked and into which takes a bent wire H. fixed to a rod G. working horizontally in
bearings h. h¹. Within the bearings h. h' said rod G. is surrounded by a spiral
spring for the purpose hereinafter described. To one end of the rod G. aforesaid,
beyond the bearing his provided a small hook i. to allow of the attachment thereto
of a cord, which, passing over the small pulley I. is secured to a suitable treadle
provided in any convenient position beneath the table upon which the apparatus is
fixed, but which as forming no part of my Invention I have not shewn in the
drawings. The other end of the rod G, beyond the bearing h¹ has a screw thread
formed thereon, and is provided with a thumbscrew devised for the purpose of
regulating and limiting the horizontal motion or "play" of the rod G and conse-
quently the action of the whole mechanism.
To the base plate A. is fixed a second pawl F. of such length as to act upon the
ratchet wheel E. at whatever height the latter may be, said pawl F. being gently
pressed against the ratchet wheel by the spring j. Figs. 3 and 4. The upper part of
the vertical spindle D. has a fine screw thread of any desired pitch cut thereon, which
works in a metal disc 7. screwed to the base plate A. The other extremity of the
vertical spindle D is plain, it moves freely in a bearing formed in a rigid bracket J.
and serves to keep said spindle D. perfectly central relatively to the tube b. above
described. The spindle D. terminates at its upper extremity in a conical formation o,
upon the apex of which is a plug m. which, whilst not being unduly loose, may move
freely up and down in unison with the vertical motion of the spindle D. aforesaid.
The mode of working the apparatus is as follows:-that is to say -Having
adjusted the thumb screw i¹, the treadle is depressed, and by means of the cord n.
attached to the rod G, the latter is drawn forward in the direction of the arrow, a
distance limited by the position of the thumbscrew and in this forward motion,
carries with it, by means of the wire H, the arm d; whereupon the pawle (which as
above referred to, is fixed upon said arm d) now takes into the ratchet wheel E. and
rotates the latter a distance corresponding to one, two or more teeth, thus raising the
plug m. and object to be operated upon, to such a height as to allow of a slice or
sectional film to be taken therefrom in accordance with the thickness desired, and first
before determined upon. It will be obvious therefore, that the whole of the mechanism
is actuated by the depression of the treadle, thus leaving both hands free to manipulate
the razor or section knife, as also to vary the position of the object being operated upon.
It is well known that in preparing objects for microscopic examination, it is almost
impossible, by the methods at present generally adopted, to obtain very thin sections
or slices of substances of a brittle or nonelastic nature, this difficulty is to some extent
due to the inability to utilise both hands for manipulating the razor or section knife
before referred to, but with the improved apparatus above described, inasmuch as the
mechanism is actuated by the foot, both hands are available to give to the cutting
knife those exact movements so essentially necessary to the successful production of
extremely fine, thin, delicate films; therefore the brittle substances having been
treated in any of the usual ways to impart tenacity and partial elasticity thereto, the
knife is made to approach and cut into the substance of the object, either direct,
diagonally, or in any other desired manner, without fear of one part of the film or
slice being of greater thickness than another, a most important consideration with
respect to opaque or semi opaque substances. Another important feature in the
device arranged as above described, is the rigidity with which the object to be
operated upon is maintained in position, during the process of cutting or slicing the
same, as the means for imparting motion being situated at a distance from the
mechanism, and the latter enclosed if desired in a protective case or box, the risk
of movement, or shifting of the substance from which a film is to be cut, is rendered
impossible.

page_text: Having now particularly described and ascertained the nature of my said Invention
and in what manner the same is to be performed I declare that what I claim is :-
Firstly. For obtaining extremely thin sections of various substances, the improved
microtome, substantially as herein described and shown in the accompanying
drawings.
Secondly. In a microtome the method of and means employed for bringing into
position the substances from which a thin section is to be cut, substantially as herein
set forth and shown in the accompanying drawings.
Thirdly. In the improved microtome above referred to, the means employed for
imparting motion to the mechanism thereof, substantially as herein set forth.
Dated this Thirteenth day of July 1887.
JAMES STEVENSON,
Gray's Inn Chambers,
20, High Holborn, London, W.C.,
Agent for Application.