An Improvement in the Method of Attaching Armour Plates to Ships or other Structures.
Year: 1891

page_text: Date of Application, 22nd Oct., 1891
Complete Specification Left, 7th July, 1892-Accepted, 13th Aug., 1892
PROVISIONAL SPECIFICATION.
An Improvement in the Method of Attaching Armour Plates
to Ships or other Structures.
I, TOLMIE JOHN TRESIDDER, Captain, late of H.M. Royal Engineers, now of
the Atlas Steel & Iron Works, Sheffield, in the County of Yorkshire do hereby
declare the nature of this invention to be as follows:-
By the ordinary method of erecting, armour plates are bolted to a backing
usually of wood, and, owing to unavoidable inequalities both in the front of the
backing & in the backs of the plates, the latter are bedded only on a series of
points not necessarily close together. The result I believe to be to facilitate the
cracking of the plate when struck by a shot, as there is nothing to prevent the
vibration of the plate between the points of hard bearing. I therefore propose
that a thin layer of a suitable material should be interposed between the plate and
its backing to give a practically continuous & firm contact between the two over
their whole surface. By a suitable material I mean one that can be easily applied
to a vertical surface of wood or iron, and that is plastic and compressible when first
put on but becomes hard & rigid after a time; and the material I prefer and have
found to give excellent results is Portland cement. Such material is to be spread
on the back of each plate, and the plate is then to be at once bolted firmly in its
place, so that all the cement or other material in excess is squeezed out and the
remainder forms a rigid & exact filling for all the spaces that would otherwise exist
between plate and backing.
Dated this 21st dor of October 1801
T. J. TRESIDDER.
COMPLETE
SPECIFICATION.
An Improvement in the Method of Attaching Armour Plates
to Ships or other Structures.
I, TOLMIE JOHN TRESIDDER Captain, late of H.M. Royal Engineers now of
the Atlas Steel and Iron Works Sheffield in the County of Yorkshire, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement :-
By the ordinary method of erecting, armour plates are bolted to a backing
usually of wood and owing to unavoidable inequalities both in the front of the
backing and in the backs of the plates, the latter are bedded only on a series of
points not necessarily close together. The result I believe to be to facilitate the
cracking of the plate when struck by a shot, as there is nothing to prevent the
vibration of the plate between the points of hard bearing. I therefore propose
that a thin layer of a suitable material should be interposed between the plate and
its backing to give a practically continuous and firm contact between the two over
their whole surface. By a suitable material I mean one that can be easily applied
to a vertical surface of wood or iron, and that is plastic and compressible when first
put on but becomes hard and rigid after a time; and the material I prefer and have
found to give excellent results is Portland cement. Such material is to be spread
on the back of each plate, and the plate is then to be at once bolted firmly in its
place, so that all the cement or other material in excess is squeezed out and the
remainder forms a rigid & exact filling for all the spaces that would otherwise exist
between plate & backing.

page_text: In order to facilitate the adhesion of the fresh cement to the vertical back of
the plate, it is advisable that a very thin layer of cement should be carefully
trowelled on and allowed to set hard before the plate leaves the manufacturers'
works. This will adhere very strongly to the plate if care be taken that all grease
is removed before it is applied, and to this thin layer any cement subsequently
applied will also strongly adhere. It is to be understood however that the process
does not depend in the least for its efficacy on the adhesion of the cement. If the
space between the plate and backing is everywhere filled with compressed cement
(the less cement the better provided this condition is fulfilled) it is of no con
Bequence whether the cement adheres to its surroundings or not, but when, as is
usually the case, vertical plates are erected against vertical backing, some adhesion
is necessary to keep the cement temporarily in its place till the backing can be
screwed up to compress & imprison all that is opposite hollow places & to squeeze
out all that is opposite ridges and that is otherwise superfluous.
In cases when pure cement would lose its plasticity before the process of
screwing up could be completed, a more slowly setting material may be employed
such as cement mixed with sand, hydraulic lime mortar, common mortar, red &
white lead with oil or boiled oil or in short any substance which is temporarily
plastic & permanently hard.
As a variation in the method of application of the process strong grout made of
Portland cement and water might be poured into the narrow space (say half an
inch) purposely left between plate and backing before finally screwing up,
precautions of course being taken to prevent the escape of grout at the sides and
bottom of the space. In such a case the screwing up should be postponed till the
grout had lost its fluidity but not its plasticity.
Having now particularly described and ascertained the nature of my said invent
tion and in what manner the same is to be performed, I declare that what I
claim is :-
(1) In the attachment of armour plates to ships or other structures the process
herein described which consists substantially in the interposition between each or
any plate & its backing of a plastic substance which retains its plasticity for a
certain time only & subsequently becomes hard and rigid.
(2) The method herein described of obtaining a practically continuous & firm
contact between armour plates & their backing which consists substantially in the
use of Portland cement or other cement, or mortar or any kindred substance in the
manner described.
Dated this 4th day of July 1892.