Improvements in and relating to Planimeters or Means for Ascertaining the Areas of Steam Indicator Diagrams and other. Figures.
Year: 1896

page_text: Date of Application, 6th Oct., 1896-Accepted, 7th Nov., 1896
COMPLETE SPECIFICATION.
Improvements in and relating to Planimeters or Means for
Ascertaining the Areas of Steam Indicator Diagrams and other.
Figures.
I, ALPHEUS CREGG LIPPINCOTT, a citizen of the United States, residing at
942 Eighth Avenue, in the City of New York, County of New York, and State of
New York, United States of America Inventor, 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 :-
This invention contemplates certain new and useful improvements in planimeters.
In ascertaining the arrears of steam indicator diagrams and other figures, it is
essential that accuracy be observed and the reading of the marks or scales be capable
of easy accomplishment. It is well known that scale-bars for indicating the areas,
in connection with measuring wheels, are affected by atmospheric influences, which
seriously impairs their accuracy. By my invention I seek to avoid this difficulty.
This I accomplish by providing a hollow shaft for the measuring wheel, said shaft
being of glass or other translucent material and enclosing therein scales of
graduation, preferably printed on paper. The ends of the shaft are closed, and said
shaft being removably held to the frame of the planimeter a series of such shafts may
be used interchangeably. In planimeters the length of the diagram controls the
distance between the pivot of the frame and the tracing point of the tracer-bar. It
has been customary to mount pointed lugs over these two points and they are brought
into coincidence with the length of the diagram to be measured by turning the entire
instrument over or partly so in making the necessary measurements. A source of
inaccuracy is introduced from the fact that these two points may not be exactly the
same distance apart as the two measuring points above which they are located. To
overcome this I provide the frame of the planimeter with a depressible pin the point
of which is preferably directly beneath or in alignment with the pivot of the frame.
This pin is normally held out of the way when not in use by means of a spring,
but can be forced down while the instrument is being adjusted for length, the point
of this pin and the tracer point corresponding with the pointed lugs heretofore used.
In this way it is not necessary to turn the instrument over to ascertain the length of
the card.
The invention will be hereinafter fully set forth and particularly pointed out in the
claims.
In the accompanying drawing :-
Figure 1 is a plan view.
Figure 14 is a detail perspective view.
?
Figure 2 is a sectional view on line 2-2, Figure 1. Figure 3 is a similar view on
line 3-3, Figure 1.
Figure 3 is a detail sectional. view.
Figure 4 is a view like Figure 3, showing a slight modification.
Figure is a view of a modified form of the shaft holder.
Figure 6 is a view of a modified form of tracer-bar and guide.
Referring to the drawing, A designates the frame, which consists of an oblong
block; and a the tracer-bar which is extended through a longitudinal opening in the
block and held at any desired point by a set-screw a'. Through a threaded opening
in one end of this tracer-bar is passed a screw b which serves as a tracer-point.
A fulcrum bar B is pivotally connected at one end to the underside of frame A by a

page_text: .
screw b', its free end having a pointed pin 6 for holding that end of said bar. This
acts as a guide for the instrument. This screw b¹ is made hollow and through it and
a vertical opening in frame-block A is passed a pin 6 having a lower pointed end b
and an upper head 6. A coil-spring encircling this pin serves to hold the latter
68
elevated so as not to contact with the card while the planimeter is being used, but
when the length of the card is to be ascertained, or the tracer-bar adjusted according
to such length, the pin is depressed. In this way the lower point of pin band
pin serve as the measuring points, avoiding turning over the instrument. In lieu
of this form of depressible pin, the latter may be formed with angular end-portions 6
and held to the side of the frame-block A by keepers 68, and a plate-spring can
serve to hold the pin normally elevated. (See Figure 4.) The forward end of the
tracer-bar may be extended and slightly curved to one side and bent downwardly, as
at b* (Figure 6) so that its extreme end will fit in and be movable on a grooved
guide-bar 6xx.
(designates the measuring-wheel having an elongated hub d; and is the shaft
therefor which is removably held to frame A by a split-sleeve d extending from one
side of said frame. Or in lieu of this sleeve a separate socket ds for each shaft may
be employed. (See Figure 5.) This socket has a threaded shank at and a hollow
ball-end d in which the end of the shaft may be securely held by melted shellac.
When this form is employed the removal of the shaft necessitates the removal of its
socket, but in using the split-sleeve the shaft is separable therefrom. This shaft is
made of translucent material, preferably glass, and is formed at its outer, closed end
with a peripheral flange d. Within this shaft is a graduated scale D preferably
composed of a narrow strip of paper on which the scales are printed. The scales of
different shafts vary according to the different scales of measurement. After the
scale is inserted in the translucent shaft the inner end of the latter is sealed, as by
a wax-held stopper e, so as to preclude atmospheric influences upon the scale.
The advantages of my invention are apparent to those skilled in the art. It will
be observed that the shaft can be easily removed for effecting the interchangeability
of scales of different measurement and that the reading of the scales is readily
accomplished, one of the edges of the wheel-hub being the point of indication.
The scales are protected from the atmosphere and hence their accuracy is insured.
The adjustment of the tracer-bar is easily accomplished and the length of the card
readily ascertainable without necessitating the reversal of the planimeter. The
depressible pin is held out of the way while the instrument is being used and can
be quickly depressed for bringing the tracer-bar pin into coincidence therewith.
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. A planimeter provided with a measuring wheel having a rotary and longitudinal
movement, a shaft therefor of translucent material, a graduated scale enclosed in said
shaft, and a tracer-bar, as set forth.
2. A planimeter provided with a measuring-wheel having a rotary and longitudinal
movement, frame, a shaft for said wheel removably held at one end to said
frame and formed of translucent material, a graduated scale enclosed.in said shaft, a
tracer-bar, and a guide therefor, as set forth.
3. A planimeter provided with a measuring-wheel having a rotary and longitudinal
movement, a frame, a tracer-bar, a guide therefor, a holder extending from one side
of said frame, a hollow shaft for said wheel secured in said holder and formed of
'translucent material, and a graduated scale within said shaft, as set forth.
4. In a planimeter having a wheel capable of a rotary and longitudinal movement,
a: hollow shaft for said wheel, of glass and closed at its ends, and a graduated scale
within said shaft, substantially as set forth.
.: 5. In a planimeter. having a frame and an adjustable tracer-bar, a depressible pin
carried by said frame, and a spring engaging said pin for normally holding the same
elevated, as and for the purpose set forth.

page_text: 6. In a planimeter having a frame, and an adjustable tracer-bar, a guide-bar
pivoted to said frame, and a depressible pin having its lower point in alignment with
the pivot of said guide-bar, as set forth.
7. A planimeter having a frame, and an adjustable tracer-bar, a guide-bar pivoted
to said frame, a depressible pin having its ends in alignment with the pivot of said
guide-bar, and the spring acting on said pin, substantially as set forth.
8. A planimeter having a frame-block, a tracer-bar adjustable in said frame-block
having a tracer-pin at one end, a guide-bar, a hollow screw pivoting the latter to
Baid frame-block, and the depressible spring-held pin extended through said hollow
screw and a coincident opening in said frame-block, substantially as set forth.
9. The herein-described planimeter, comprising the frame-block, the longitudinally-
adjustable tracer-bar, the removable shaft, having a graduated scale, the wheel thereon,
the pivoted guide-bar, and the depressible pin having its ends in line with the pivot
of said guide-bar, substantially as set forth.
Dated this Sixth day of October 1896
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.