AN IMPROVED BIT FOR DARDA MARIANG TE WOOD OR OTHER MATERIAL PROVISIONAL.
Year: 1865

page_text: LETTERS PATENT to William Tighe Hamilton, of No. 2, Belgrave
Square, Rathmines, Dublin, for the Invention of "AN IMPROVED BIT FOR
DARDA MARIANG TE WOOD OR OTHER MATERIAL
PROVISIONAL. SPECIFICATION left by the said William Tighe Hamilton>
at the Office of the Commissioners of Patents, with his Petition, on the
6th November. 1865.
WILLIAM TIGHE HAMILTON, of No. 2, Belgrave Square,.. Rathmines,
Dublin, do hereby declare the nature of the said Invention for "AN, IMPROVED
BIT FOR BORING. MORTICES IN WOOD OR OTHER MATERIAL," to be as follows:-
It affects the operation of morticing by means of a spiral bit, the end of
which is shaped into any of the usual forms of boring bits (for first passing
through the object to be morticed), but the spiral sides of which are so formed
and sharpened as then to cut sideways, when the object is made to travel
sideways, in the way commonly called "slotting." The bit is formed out of a
bar of steel, thick along the centre of its length, but thin at the edges, and
so twisted that these edges may form a suitable angle with the axis of the
spiral; that of about 45° degrees seems preferable. The action is increased
when the edges are divided into distinct cutters by filing away small portions
or vacancies at such regular intervals that the cutter on one side shall be
opposite and cover the vacancy on the other. The preferable proportions
seem to be two-ninth parts of the circumference for each cutter, and one-ninth

page_text: for each vacancy. The action is further increased if before twisting the
spiral the under part of each edge is slightly hollowed lengthways, as in
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Tighe Hamilton in the Great Seal. Patent Office on
the 5th May 1866.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
TIGHE HAMILTON, Esquire, of Upper Rathmines, Dublin, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Sixth day of November, in the year of our Lord
One thousand eight hundred and sixty-five, in the twenty-ninth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said William Tighe Hamilton, Her special licence that I, the said William
Tighe Hamilton, my executors, administrators, and assigns, or such others
as I, the said William Tighe Hamilton, my executors, administrators, and
assigns, should at any time agree with, and no others, from time to time and
at all times thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention
for "AN IMPROVED BIT FOR BORING MORTICES IN WOOD OR OTHER MATERIAL,"
upon the condition (amongst others) that I, the said William Tighe
Hamilton, my executors or administrators, by an instrument in writing under
my, or their, or one of their hands and seals, should particularly describe
and ascertain the nature of the said Invention, and in what manner the
same was to be performed, and cause the same to be filed in the Great Seal
Patent Office within six calendar months next and immediately after the
date of the said Letters Patent.
NOW KNOW YE, that I, the said William Tighe Hamilton, do hereby
declare the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement :---
This bit is of a spiral form, its end being either spear-shaped (or of any
other usual form of auger) for penetration. Its spiral sides are formed to
cut edgways, when the object to be mortised is made to travel sideways in
the manner commonly called slotting. It may be either turned as a screw
qut of a solid piece of steel or it may be forged by twisting into a spiral a

page_text: blade of steel, thick along its middle, and thin along its edges. These
edges may be divided into distinct cutters or slightly hollowed, or at various
inclinations to the axis, according to the nature of the material to be cut.
But a continuous edge pitched at an inclination of about 45° and so formed
as to strike the end of the slot at right angles seems preferable for general
use.
In witness whereof, I, the said William Tighe Hamilton, have here-
unto set my hand and seal, this Fifth day of May, in the year of
our Lord One thousand eight hundred and sixty-six.
WILLIAM TIGHE HAMILTON. (LS.)