Improvements in and relating to Instruments for Measuring Distances.
Year: 1888

page_text: Date of Application, 14th Aug., 1888
Specification Accepted, 22nd Jan., 1889
COMPLETE SPECIFICATION.
Improvements in and relating to Instruments for Measuring
Distances.
We, JAMES BEARD FAUCETTE, residing at Argenta, in the County of Pulaski,
State of Arkansas, and HENRY LEWIS FLETCHER residing at Little Rock, in the
above named County and State, in the United States of America, Gentlemen, 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:-
The invention relates to a combination instrument which is mounted on standards
and may be used for ascertaining distances, for determining altitudes and differences
of elevation; for measuring and calculating angles, without the use of logarithms
or other intricate calculations.
The object of this invention is to adapt our improvements to ordinary surveying
instruments and provide them with tangential scales; and the improvement consists
in certain details of construction and combination of parts hereinafter described
and particularly designated in the claims.
The principle upon which the instrument works is that it takes the tangent
axis of the telescope H as the base of a right-angled triangle, and the distance
between such tangent axis and the axis of the vertical pivot (upon which the
telescope G is mounted) as the perpendicular of the same triangle. Then the
telescope G being accurately directed upon the same object as the telescope Ha
second angle is given by the reading on the sector plate E, or vertical limb I,
but instead of the angular measurement being read off, a particular scale of
tangential graduations is likewise given which is so graduated that the corre-
sponding one being used as a divisor for the square of the perpendicular the base,
representing the distance of the object, is found.
In the case of two instruments being used the distance between the two
horizontal axes is taken as the base.
In the accompanying drawings:-
Figure 1, is a perspective of our improvement applied to a transit instrument
or theodolite.

page_text: Figure 2, is a plan of the same.
We will first describe our improvement as applied to a transit instrument or
theodolite of ordinary construction, wherein a horizontal base plate, A, mounted
upon a tripod and carrying a compass-box, B, and needle, C, is fitted above a revolving
plate, D, and carries standards, D¹. The upper ends of the standards, D¹, have
bearings, d, into which are fitted the trunions, e, of the radial sector-plate, E, the radius
of which is in this instance, twelve inches, which is marked with natural tangents and
degrees for the measurement of distance.
A radius bar, F, is pivoted centrally upon the sector plate, E, and has a
telescope, G, upon its pivotal end and an index hair, f, upon its movable end to
intersect the graduations upon the sector plate, E, in the vertical plane of the
telescope.
An arc, E', forming a part of the sector plate, E, is slotted at, e¹, to receive a
clamping screw, F', pivotally connected with the radius bar, F, by a tangent screw, F2.
The radius bar may be quickly moved and secured approximately to position upon the
sector plate, E, by said clamping screw and accurately adjusted thereon by the tangent
screw.
A tangent sight or telescope, H, is pivotally secured at right angles to the trunions, e,
of the sector plate E, to revolve therewith upon its horizontal axis and is directed in
the line of the base of a right angled triangle, the perpendicular of said triangle being
in the line of the trunion axis of the instrument; and the hypotenuse of said triangle
being in the line of collimation of the telescope or the sights upon the radius
bar.
A vertical limb, I, preferably the half, or any other sector of a circle is graduated
with degrees and natural tangents of said degrees and fixed securely by brackets, I¹, I²,
upon the standards, D', and plate, D, of the instrument at right angles to the horizontal
axis of the sector plate, E, to permit the radial edge of said plate to swing upon its
trunions across the face of said vertical limb and intersect the graduations upon its
periphery. A set screw, i, or any well known means for adjustably securing the sector
plate upon the vertical limb is attached to said sector plate."
The graduations upon the sector plate, E, and the vertical limb, I consist of the
ordinary degrees, and also of tangential graduations corresponding with a standard
measurement of length to be used in the calculation of distances.
The tangential and radial sight bars or telescope, either or both are located upon
the sector plate, E, or its trunions, to extend back of its horizontal axis sufficiently to
counter-balance the weight of said sector plate and thus permit the various movable
parts of the instrument to swing freely upon their axis of rotation.
The instrument is serviceable in any survey, in both the preliminary and location
survey for railroads, and in taking topography it is particularly valuable, as distances,
slopes and points along contour lines may be determined quickly and accurately
without the assistance of chain-men or rod-men.
A correct contour map which will be valuable in determining the final location of
the line may thus be quickly surveyed and plotted by a topographer, with but litttle if
any assistance.
This instrument may be used successfully to find the range of a distant ship or.
of an enemy, and their position and distance may be obtained with great accuracy, by
placing separate instruments upon each end of a ship; the distance between said
instruments may be accurately measured by a tape for the base; the tangent
telescope H of both instruments being placed in line with the base and the radial
telescope G of said instruments sighted upon the distant object.
By the adjustment or positioning of the radial telescopes the radius bar F is also
positioned on the sector-plate E and by reading the natural tangent graduations of
the angle as indicated by said bar through the slit thereof on the sector plate and
dividing the square of the distance between the sights G and H upon the horizontal
axis of the sector plate by said tangent graduations, the distance of the object may be
determined.
Its low first cost and the adaptability of the tangent scale to instruments in general

page_text: use will recommend its adoption, and its simplicity of construction will suggest its use
for other purposes not herein mentioned.
Having now particularly described and ascertained the nature of our said inven-
tion. and in what manner the same is to be performed we declare that what we
claim is :-
1. In a surveying instrument the combination of the horizontal base plate and its
magnetic needle and standards thereon, a quadrant shaped graduated sector-limb, secured
at one of its radial sides to a horizontal axis supported in said standards and provided with
arc and tangential divisions, a tangential sight affixed to said limb and a radius bar
carrying sights pivoted to the horizontally pivoted limb, to move over the surface of
said sector limb, substantially as described.
2. In a surveying instrument the combination of the horizontal base plate and
standards thereon the graduated sector limb provided with arc and tangential divisions
and pivoted horizontally upon the standards and located upon one side of its axial
line; a tangential sight vertically movable with said sector limb, a radius bar carrying
sights pivoted to the sector limb, and a graduated vertical limb provided with arc and
tangential divisions and secured to the standards upon which the vertically swinging
sector limb may be adjusted, substantially.as described.
3. In a surveying instrument the combination of the horizontal base plate and
standards thereon, a revolving horizontal sector limb graduated with arc and tangential
divisions and carried on said standards a vertical limb located upon one side of its
axial line, a tangent sight secured to the revolving sector limb, and a radius bar
carrying sights and pivoted to the sector limb to swing with and move upon said limb,
substantially as described.
4. The combination in a surveying instrument of a horizontal plate carrying a
magnetic needle and standards adapted to revolve upon a vertical axis, a graduated
quadrant shaped sector limb provided with an arc and tangential divisions and pivoted
horizontally to swing upon one side of said standards, and sights one of which is
located mainly upon the opposite side of said standards to counter-balance the said
sector limb, substantially as described.
1080