IMPROVEMENTS IN BOLTS AND WASHERS
Year: 1866

page_text: LETTERS PATENT to James Chalmers, of No. 2, Bickerton Terrace,
Haverstock Hill, for the Invention of "IMPROVEMENTS IN BOLTS AND
WASHERS."
Sealed the 26th March 1867, and dated the 1st October 1866.
PROVISIONAL SPECIFICATION left by the said James Chalmers at
the Office of the Commissioners of Patents, with his Petition, on the
1st October 1866.
I, JAMES CHALMERS, of No. 2, Bickerton Terrace, Haverstock Hill, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN BOLTS
AND WASHERS," to be as follows:-
This Invention has for its object to prevent the breaking of bolts by sudden
concussions, such as are caused by the impact of shot on armour plates
attached to ships of war or fortifications. As bolts subjected to sudden
concussions are liable to break at the thread, where the cross section is
reduced I propose to increase the size of the bolt and reduce the section of
the shank so as to be equal to the section at the bottom of the thread in the
following manner:-Taking a bolt, say, 2 feet in length and 2 inches in
diameter, the area of the cross section would be about.5 inches, and allowing
for depth of thread one-eighth of an inch, the area of cross section at bottom
of thread would be about 4 inches, hence the shank of the bolt would be
reduced one inch. This reduction I propose to effect by a slot through the
centre of the shauk, commencing at, say, one inch from the termination of the

page_text: screw thread, and ending about an equal distace from the inner part of the
head of the bolt. This slot, to facilitate making and lessen cost, I propose
shall be made in making the bolt; the iron of which the bolt would be made
would be a half round (or nearly half round) bar, two pieces of which of the
length required shall be placed opposite, flat sides facing each other, with a
piece of iron of the same breadth and inch thick or so between them at each
end, which when welded would make the solid part of the bolt, leaving the
space between to form the slot aforesaid. This slot when the ironwork was
finished would be filled with a slip of wood or iron driven in tight with
marine glue or some other adhesive substance to secure it; a bolt thus formed
could be of the same diameter throughout its entire length, thus filling the
hole and making a good fit. For washers for armour plate bolts, or where
sudden concussions are expected, I propose to use next the skin of the ship or
surface to be acted on a wooden or other cushion washer of tough but not too
hard materials of, say, from half inch to one inch in thickness, then an iron
washer of, say, a quarter or half inch thick, having its outer edge pressed or
turned down, say, a quarter inch, so as to surround and embrace the cushion
washer in order to prevent its falling out in case of its being fractured.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said James Chalmers in the Great Seal Patent Office on the
27th March 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
CHALMERS, of No. 2, Bickerton Terrace, Haverstock Hill, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the First day of October, in the year of our Lord
One thousand eight hundred and sixty-six, in the thirtieth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said James Chalmers, Her special licence, that I, the said James Chalmers,
my executors, administrators, and assigns, or such others as I, the said James
Chalmers, 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 "IMPROVEMENTS IN BOLTS AND
WASHERS," upon the condition (amongst others) that 1, the said James.
Chalmers, my executors or administrators, by an instrument in writing

page_text: 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 Letter's Patent.
NOW KNOW YE, that I, the said James Chalmers, 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 Invention has for its object improvements in bolts and washers, chiefly
such as are used in fastening the armour plates of ships of war and
fortifications. The chief object sought to be obtained by making the area of
the cross section of the body of the bolt about equal to the area of the section
at the thread is to prevent it snapping under a sudden concussion by
obtaining a certain stretching range in the shank of the bolt itself, and the
advantages of the following method are, that this object is obtained
economically, and that the bolt, being parallel or of an equal size from the
head to the screw can be made to completely fill the hole.
DESCRIPTION OF THE DRAWINGS.
Fig. 1 shows a bolt suitable for such armour as that of the improved
Warrior system with 8-inch plates and 18 inches of timber backing, and is
shown on a scale of 6 inches to the foot. The slot a, a, is shown filled with
a piece of wood which can be secured with marine glue or any other suitable
adhesive substance. The wooden washer c of elm or other tough wood will
fit into the iron washer d, as shown in Figs. 1 and 2, and rest upon the skin
plate b. For the thread of the bolt I prefer a shallow square thread, (such
as described in the Specification of my Invention for "Improvements in
Armour for Vessels of War, &c," for which I obtained Her Majesty's Letters
Patent dated the 19th November 1862, No. 3105,) or any shallow thread that
will not cut away the section of the bolt too much. Fig. 2 shows a section of
the bolt through A, B, and of the washers through C, D. Fig. 3 is a
longitudinal section on the same scale of the bars of which these bolts will be
made. The bars e, f, are rolled in a shape nearly half round, of which a
cross section is shown, Fig. 4; they are put together, as shown in the
Drawing, with the pieces g, h, between them at the ends. The ends with the
said pieces are then welded together, forming a solid head and point, leaving
the slot i to be filled in with wood, as shown in Figs. 1 and 2. Fig. 4 is a
cross section of Fig. 3 on A, B.

page_text: I wish it to be understood that I do not confine myself to the exact details,
dimensions, or proportions of the foregoing description of my Invention and
the accompanying Drawings; nor do I limit the use of these bolts to the
fastenings of armour plates only.
In witness whereof, I, the said James Chalmers, have hereunto set my
hand and seal, this Eighteenth day of March, in the year of our Lord
One thousand eight hundred and sixty-seven.
JAMES CHALMERS. (L.B.)