Improvements in Plumb Bobs.
Year: 1892

page_text: Date of Application, 1st Nov., 1892-Accepted, 3rd Dec., 1892
Improvements in Plumb Bobs.
I, HERBERT MORTON FULLER Civil Engineer of 1525 Indiana Street in the
City and County of Philadelphia, State of Pennsylvania, one of the United States
of America, 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 improvements in plumb bobs and particularly to
improvements in surveyors' plumb bobs and the object of my invention is to
furnish a plumb bob with an extensible point which may be advanced from time
to time as its extremity is worn away and which may at trifling expense be
entirely renewed.
The points on plumb bobs, and particularly on the ones used by surveyors, are
usually made of steel and attached to the body of the plumb bob by screwing them
into its end. These points are subjected to very hard usage, being frequently used
to make scratches or marks on stone and bricks and for other purposes of a
similar nature; the consequence is that the points soon become worn away and the
plumb worthless.
My improved plumb bob is furnished with a long point or spindle which passes
up into the interior of the plumb bob and which can be operated by means of a
screw, in order to push it out beyond the body of the plumb bob as its point wears
away and which, when completely worn away, can be withdrawn and replaced with
no trouble and very slight expense.
In the accompanying drawings forming part of this Specification and in which
similar letters of reference indicate similar parts throughout the several views:-
Fig. 1 is a central sectional elevation of a plumb bob embodying my invention;
Fig. 2, a central sectional elevation of a plumb bob showing a modification of
my invention; and
Fig. 3, a similar view showing another modification.
A is the plumb bob, which is furnished with a threaded hole B, extending from
its top down along its vertical axis, as shown, to within a half inch or an inch of
its bottom. C is the point or spindle, which is preferably furnished with a head D
at its top and which is smaller in diameter than the hole B, and is placed within
this hole and passes to the outside of the plumb bob through a hole E of about its
own diameter, which extends from hole B to the smaller end or point of the plumb
bob.
F is a spring surrounding spindle C which bears against the bottom of hole B
and against the bottom of head D, on this spindle, and G is a screw which travels
on and is held by the threads on the hole B; this screw bears against the top of
head D on spindle C, and by setting this screw down by means of a screw-driver
the point of the spindle may be advanced any distance desired beyond the plumb
bob.
The spring Facts to prevent the spindle from advancing further than is dictated
by the screw G.
H is the top or cap of the plumb bob and is held in place by screwing it down
in the hole B, this cap being furnished with a threaded projection I for this purpose
and with a hole K, passing through its centre, through which the cord L which
carries the plumb bob may pass.
In the modification shown in Fig. 2, the spindle C is threaded, as is the hole E,
and this spindle may be advanced by turning it by means of a screw-driver
or key.
In the modification shown in Fig. 3, a spindle, having a head D similar to that
D

page_text: shown in Fig. 1, is used; the plumb bob is also furnished with a threaded hole B
and with a screw M. This screw is furnished with a central hole M' through which
the spindle C passes, its head resting on top of the screw M. G is a screw similar
to the screw shown in Fig. 1, which bears against the head D of the spindle and
which prevents this spindle from being forced inwards, while it is prevented from
falling outwards by the screw M. In order to advance the point Ċ screw G and
spindle C are removed from the plumb bob, the screw M is set down the requisite
distance and the spindle C and screw G are again put in place.
The spindles C, when worn away so as to be useless, may be readily removed
from the plumb bobs and replaced by new ones.
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 :-
:―
1. The combination in a plumb bob of a body and a spindle within and pro-
jecting from said body and means substantially as set forth for advancing said
spindle as its point wears away.
2. The combination with a plumb bob of a spindle within and projecting beyond
said plumb bob, a head on said spindle, a threaded hole and a screw within said
hole, engaging the head of said spindle and adapted to move said spindle forward
and a spring surrounding said spindle and bearing against said head and the bottom
of said hole, substantially as set forth.
Dated this 26th day of September 1892.
HERBERT MORTON FULLER.
H. D. Fitzpatrick,
70, Wellington Street, Glasgow, Agent.