CERTAIN IMPROVEMENTS ON SAW MILLS
Year: 1812

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, MARC
ISAMBARD BRUNEL, of Chelsea, in the County of Middlesex, Gentleman,
send greeting.
WHEREAS His most Excellent Majesty King George the Third did, by
His Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Twenty-eighth day of
January, in the fifty-second year of His reign, give and grant unto me, the
said Marc Isambard Brunel, my exors, admors, and assigns, His especial
licence, full power, sole privilege and authority, that I, the said Marc
Isambard Brunel, my exors, adiñiors, and assigns, should and lawfully might,
during the term of years. therein mentioned, make, use, exercise, and vend,
within England, Wales, and the Town of Berwick-upon-Tweed, my Invention
of "CERTAIN IMPROVEMENTS ON SAW MILLS;" in which said Letters Patent there
is contained a proviso that if I, the said Marc Isambart Brunel, shall not
particularly describe and, ascertain the nature of my said Invention, and in
what manner the same is to be performed, by an instrument in writing under
my hand and seal, and cause the same to be enrolled in His Majesty's High
Court of Chancery within two calendar months next and immediately after the
date of the said Letters Patent, that then the said Letters Patent, and all
liberties and advantages whatsoever thereby granted, shall utterly cease, deter-
mine, and become void, as in and by the same, (relation being thereunto had)
may more fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
Marc Isambard Brunel, do hereby declare that my Improvements on Saw
Mills consist in the mode of fixing a saw or saws in the frame in which they
are to work, and likewise in the method of keeping the cutting edge of the
saw true, it being a desideratum that saws fixed into frames which are to be
worked by michinery should be kept in the best cutting state, and should
likewise be placed at and shifted to any distance from each other as the work
to be performed may require. I propose, in order to obtain these advantages
with both expedition and accuracy, to have the saws so fixed as to be easily
put into place and removed at pleasure, and to have them so prepared
previous to their being applied to the frame as to be, when fixed, true and
parallel.in every respect with the sliding motion of the frame.
The most expeditious mode for fixing saws to the frames, particularly when
they require to be very close to each other, is by hooking them at both
extremities in the manner represented in the annexed Drawings. A 1, A 2,
Fig. 1 and 2, represent the hooks fixed to the saws, the lower end of which is
hooked to the under head at A 2, and the upper end to the tiller B. The
tiller B, passing, in the way hitherto practiced, through the upper head of the
frame, is held fast by means of a wedge or of a screw and nut in the usual
manner, both these means being objectionable: the first on account of the
wear and tear of the wedges, which are driven in with hammers, and the
second on account of the space required for the .nuts. I propose to add to the
frame a stretching apparatus consisting of a transversal bar c, Fig. 1, 2, 3,
parallel with the upper head, resting at its extremities in two standards or
screws D, D, Fig. 1 and 4. These standards or screws may be raised or
lowered by means of levers or wedges; but I give the preference to endless
screws E, E, Fig. 1 and 4, working into wheels F, F, Fig. 4, and turned by
the assistance of a handle G, Fig. 1 and 4. The movable strap represented
at H, Fig. 1, 2, and 3, being connected, by means of a wedge J, Fig. 1 and 2,
or of a hook 'a, Fig. 3, to each tiller, is intended to assist in drawing up the
saw and in stretching it to the degree of tightness required. When in that
state, the wedge K, Fig. 2, is pushed in by hand, instead of being driven
by the aid of a hammer. The bar being then lowered, the strap is ready to be
applied to another tiller, and so on successively until every saw is brought to
its working order. In lieu of a wedge a small paul 6, Fig. 3, may be intro-
duced, on account its requiring less room than the wedge. In order that the
saws, which are to be fixed into the frames in the manner before specified,
may be so prepared as to be in every respect true with the sliding motion of
the frame, I propose to have each saw stretched by means of corresponding

page_text: hooks, sec A, Fig. 5 and 6, into an apparatus represented in Fig. 5 and 6,
in which the saws are to be filed and sharpened, and set by means of
knippers adjusted for that purpose. It being equally important that the front
edge of the teeth should be square with the cut of the saw, I propose to have
the teeth touched now and then (when it may be found expedient) with a
sliding instrument represented at B, Fig. 5, 6, and 9. This instrument carries
at C, Fig. 5 and 9, a small file or a burnisher, which is intended to keep the
extreme point of the teeth of the saws perfectly true, and thereby prepare them
before they are applied to the frame. The file or burnisher, which, in order
to be made more conspicuous, is colored in red, in Fig. 5 and 9, can be
lowered at pleasure, according to the breadth of the saw. The instrument B,
Fig. 5, 6, and 9, is intended to slide on the strait edges of the apparatus c,
Fig. 5, 6, and 9. It is obvious that if the saw frame represented in Fig. 1 is
constructed with great accuracy, every saw prepared by the assistance of the
apparatus represented in Fig. 5 and 6 will, when fixed on such a frame,
correspond with each other, and be true with the sliding motion of the frame.
In witness whereof, I, the said Marc Isambard Brunel, have hereunto
set my hand and seal, the Twenty-sixth day of March, in the year
T