IMPROVEMENTS IN THEODOLITES
Year: 1872

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine,
Lake, & Co., Patent Agents, Southampton Buildings, London, for
the Invention of "IMPROVEMENTS IN THEODOLITES." -A communica-
tion from abroad by Upton Felton Biggs, of Oakland, Maryland,
United States of America.
Sealed the 24th May 1872, and dated the 5th April 1872.
COMPLETE SPECIFICATION filed by the said William Robert Lake
at the Office of the Commissioners of Patents, with his Petition
and Declaration, on the 5th April 1872, pursuant to the 9th Section
of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London, send greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS IN
THEODOLITES," and have petitioned Her Majesty to grant unto me, my
executors, administrators, and assigns, Her Royal Letters Patent for
こ

page_text: the same, and have made solemn Declaration that it has been com-
municated to me from abroad by Upton Felton Biggs, of Oakland,
Maryland, United States of America.
NOW KNOW YE, that I, the said William Robert Lake, do hereby
declare that the following Complete Specification, under my hand and
seal, fully describes and ascertains the nature of the said Invention, and
in what manner the same is to be performed, in and by the following
statement, reference being had to the accompanying Drawing, in which
Figure 1 is a plan or top view of a theodolite embodying this Invention;
Figure 2 is a view in perspective of the same in a horizontal position for
the measurement of distance; Figure 3 is a similar view of the said
instrument in a vertical position for the measurement of elevations and
depressions.
This improved theodolite consists of a quadrant the bases A, B, and
the arc C of which are provided with scales; those of the bases are in
divisions of the twenty-fourth part of an inch, and the outer one D of
the arc C has corresponding spaces in two equal divisions of 140 each,
making in all 280, each being the twenty-fourth part of an inch, while
the inner scale E is laid off in degrees of the circle in the usual manner.
At the point where the inner eyes of the two bases A, B, meet is formed
the centre F of the compass G, and the distance from this centre F,
which forms the centre of the circle whereof the arc C is a part, to the
outer scale D is exactly eight inches and a quarter, being the twenty-
fourth part of a rod, so that the divisions of the outer scale are in the
proportion of one inch to the rod to a line from the compass centre F to
the circumference of the said scale. An intermediate arc H serves for
the attachment of the centre pivot I of the instrument and the support
of the transit bar J, which being pivotted beneath the centre F of the
compass extends a suitable distance beyond the arc of the quadrant and
the meeting point of its bases to receive and support the usual sight
standards K, and is supported at its outer end upon the arc C by a guide
plate L. The sight line of the transit bar J is indicated across the arc
by a hair line a, held by a pin 6 and screw c of the said bar. Each base
of the quadrant is provided with a level M or M₁ for use with the
quadrant in a horizontal position, as shown in Figures 1 and 2.
level N is arranged at a right angle to the level M', and is supported in
the example shown upon the flange of the supplemental tripod socket,
the level M having its opposite. sides open to act in conjunction with
A third

page_text: the level N, and thereby obtain the advantage of two levels whether the
instrument be used in a vertical or horizontal position, as shewn in
Figure 3. At a suitable point on the outer edge of the base A is attached
a tripod socket P, to allow the quadrant to be used in a vertical position,
while the socket I secured to the under side of the intermediate arc H
serves for the tripod attachment when the quadrant is used in a horizontal
position.
The scale D is projected on the arc C in the following manner, viz. :-
Two and a quarter inches on each of the bases A and B from the end are
laid off in twenty-fourth parts of an inch, and lines are projected from
each of these divisions at right angles to the bases. Where these lines
cross the line of the periphery of the outer scale D of the arc C, these
twenty-fourth parts of an inch are laid off on the arc radially, and in this
way beginning at each end of the arc, 140 twenty-fourth parts of the
inch are laid off on the arc towards the centre, or 280 such divisions on
the entire arc. These divisions on the arc C of course increase in size in
regular graduation from each end towards the centre, so that every one
of these divisions is in true and correct relative proportion to its base of
one inch to the rod with every degree of inclination.
The operation of this instrument is as follows:-If it is desired to
measure the height of an object the quadrant is placed' vertically on the
tripod, the socket P on the base A serving for that purpose, and it is by
means of the two levels M¹ and N set true. The transit bar J then being
moved until the line of sight strikes the object or point the height of
which is to be ascertained, it is held on that point by means of the guide
Land a clamp screw d at its outer end. Suppose the hair or thread a is
then directly over the line in the outer scale D of the arc C opposite the
number 84, this indicates that the line from the instrument to the top of
the object rises at an elevation of 84 inches or 7 feet to the rod. The
instrument is now raised in as nearly a vertical line as possible to a
higher point until a difference of declension of one division on the scale
D is obtained. Suppose that it requires an elevation of the instrument
of 15 feet to obtain this difference of one inch to the rod, consequently
it would require 12 × 15, or 180 feet elevation of the instrument to
make a declension of one foot. The elevation of the line of sight being
originally however seven feet to the rod, it will be obvious that the
height of the object must be 7 × 180, or 1,260 feet. Or the calculation
would be really made in the following manner:-Elevation 84 inches,

page_text: declension 15 feet to the inch, 84 × 15, 1,260, thus avoiding, first,
the division of 84 by 12, and afterwards the multiplication of 15 by 12.
To measure distance the instrument would be placed horizontally, the
socket I being on the tripod and the instrument set level by the levels
M, M'. The compass being adjusted the line of sight is brought to bear
on the object; if the hair or thread a then indicates, for instance, 42,
and in a direction, say, east, 12 inches south, the instrument indicates
that there is a departure of 12 inches from the base line to the rod. By
now moving the instrument south sufficiently to give one inch departure
from the former line (and in order to obtain this one inch departure it is
required to move the instrument one foot), it will be determined that
the extent of the departure is one foot for every rod. The departure
being 12 x 12 inches, or 12 feet, the distance from the object will
be 12 rods.
I am aware that theodolites have been constructed with a view of
rendering elaborate calculations unnecessary, and this object has been
sought to be attained by a complicated and expensive construction of
the instrument, but I am not aware of any case in which the instrument
has been constructed in relative proportions of inches to rods or where
any such relatively proportioned scale has been used; nor am I aware
that a socket has been applied to one of the bases of the instrument to
render the same applicable for use horizontally or vertically, nor that
the above-described arrangement of the levels for either horizontal or
vertical use has ever been devised before.
I have shewn a scale of degrees upon the arc of the quadrant; I do
not however use it in making first measurements, but only to reduce
measurements, which may have already been taken by other instru-
ments in degrees, to rods, feet, and inches by my new quadrant scale
projected from the bases and maintaining a relative distance to the
measuring centre to produce certain results, although my instrument,
being provided with a degree scale, may be used for degree measure-
ments where necessary or desirable..
This improved theodolite is extremely simple in its construction, is
easily handled, and may be employed in the various uses for which
theodolites are required. By it the rate of speed of vessels at sea and
their distance from another vessel or given point may be easily and
rapidly determined. All its parts are such as will not easily get out of

page_text: order. It combines all the different surveyor's and engineer's instru-
ments, the compass, the transit, the quadrant, and the level; it finds its
own meridian and gives every slope; it gives length and breadth,
depression and elevation; by it the distance to any object can be found
as quick as thought. The whole instrument costs no more than the old
compass and can be easily carried. It is to a man as a calculator or an
interest table, and with a little explanation can be easily understood.
Having thus fully described the nature of my said Invention as com-
municated to me by my foreign correspondent, and the manner of
performing the same, I claim,-
First. The quadrant C having its outer scale of feet and inches pro-
jected as described in connection with its exact projection from and
relation to the compass centre for the purpose set forth.
Second., The socket P arranged on the base A to serve for using the
theodolite in a vertical position, essentially as described.
Third. In combination with the level M¹ the level N arranged as
described in order to balance the instrument when used in a vertical
position, essentially as and for the purpose set forth.
Fourth. The combination in a theodolite of the bases A, B, arc C,
provided with scales D, E, transit bar J with its sight standards K,
intermediate arc H, levels M, M', and N, sockets I, P, and compass G,
all arranged for use essentially as described.
In witness whereof, I, the said William Robert Lake, have
hereunto set my hand and seal, this Fifth day of April, in
the year of our Lord One thousand eight hundred and seventy-
Witness,
E. C. JACKSON.
W. ROB. LAKE. (L.S.)