An Improved Slip Joint for Mathematical and other Instruments.
Year: 1886

page_text: Date of Application, 16th Sept., 1886.
Complete Left, 16th June, 1887.
Complete Accepted, 19th July, 1887.
PROVISIONAL SPECIFICATION.
An Improved Slip Joint for Mathematical and other Instruments.
I, WILLIAM HENRY HARLING, of 40, Hatton Garden, in the County of Middlesex,
Mathematical Instrument Maker, do hereby declare the nature of this invention to
be as follows:-
My invention relates to an improved slip joint for connecting the loose parts of
mathematical and other instruments, and consists in dispensing with all feathers, set
screws, bayonet joints or the like, the result being that by my invention I produce a
joint at once cheap, efficient, simple, and durable.
In carrying my invention into effect, I bore the socket parallel and circular in
section, and make the male fitting of a circular section but tapering towards its end.
The male fitting is slipped into the socket, when a slight pressure causes the edge of
the socket to tightly embrace the tapered surface of said fitting.
PHILLIPS & LEIGH,
Agents for the Applicant.

page_text: An Improved Slip Joint for Mathematical and other Instruments.
I, WILLIAM HENRY HARLING, of 40, Hatton Garden, in the County of Middlesex,
Mathematical Instrument Maker, 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 relates to an improved slip joint for connecting the loose and
exchangeable parts of mathematical and other instruments, of an analogous con-
struction, and consists in dispensing with all feathers, set-screws, bayonet-joints, or
the like; the result being that, by my invention, I produce a joint at once cheap,
efficient, simple, and durable.
In carrying my invention into effect, I bore the socket either parallel or taper, and
circular in cross section. The male fitting is also of a circular section, and tapering
towards its end. The latter is slipped into the socket, when a slight push causes the
socket to tightly embrace the tapered surface of said fitting.
The application of my invention to various parts of mathematical instruments is
illustrated in the accompanying drawing, which is to be taken as part of this
specification and read therewith, and in which
Fig. 1 shews my invention as applied to a compass with pencil point and one knee
joint.
Fig. 2 shews the invention as applied to a compass leg in which the knee joint is
above the slip joint.
Fig. 3 shews the application of my invention to an ink point and a drawing pen
handle.
Fig. 4 shews the application of the invention to the socket of a needle point ;
and
Fig. 5 illustrates the application of the invention to a spring bow pen.
A is the socket circular in cross section and either parallel or taper, the latter by
preference.
B is the taper male fitting, circular in cross section. The length of it is about the
same as that of the socket, but its maximum diameter at 6 is greater than that of the
socket A.
The object of making the maximum diameter of the male fitting greater than that
of the socket is that the forcible insertion of the former into the latter may slightly
expand it, whereupon a slight twist given to the fitting will cause it to bind against
or to be tightly embraced by the socket.
The point is removed from the socket by a reversal of the motions mentioned in
the last paragraph.
The advantages of the method of providing for the attachment and detachment of
the points of mathematical instruments described above with reference to Figs. 1, 2
and 5, are economy in cost of production and an increased durability in consequence
of the plain surfaces and strong cross sections made use of.

page_text: In Fig. 3, C is a holder prepared in the same way as the compass leg of either
Figs. 1, 2 or 5, to receive and hold the pen point D; the junction of the two pro-
ducing a drawing pen. It is clear that other loose parts e.g., plain or pencil points,
dotting wheels or tracers may be made in the same way.
Figs. 4 and 5 also illustrate the adaptation of my invention to produce a cheap and
efficient needle point. Hitherto the sockets of needle points have been split and
fitted with holding screws. They have sometimes been made parallel and then the
needles were necessarily specially prepared to fit. Now the application of my in-
vention enables me to produce a needle point which is at once cheap and efficient ;
and having no binding screw there is nothing to obstruct the draughtsman's view of
the actual point of the needle.
The socket a is, bored out taper and will therefore take an ordinary sewing needle
or the pointed part of one which is tightened in the socket by a push at or a tap on
the thick end thereof.
I wish it to be distinctly understood that the application of my invention is not
confined to the joints illustrated in the figures but is applicable to all the slip joints
for connecting the loose and exchangeable parts of mathematical and other instruments
of an analogous construction.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I claim
is:
The combination of a socket A of a circular cross section formed in the end of the
main part of the instrument to which the loose part is to be attached and a taper
part B of a circular cross section on the loose or exchangeable part to be joined to the
said main part, which taper part fits the said socket and may be tightened therein by
a slight push or a twist or both substantially as and for the purpose described with
reference to the accompanying figures.
PHILLIPS & LEIGH,
Patent Agents,
22, Southampton Buildings,
Chancery Lane, W.C.,
Agents for the Applicant.