IMPROVEMENTS IN THE METHODS OF AND APPARATUS FOR SURVEYING LEVELLING AND PLOTTING LAND
Year: 1882

page_text: LETTERS PATENT to Alfred Julius Boult, of the firm of W. P. Thompson
& Boult, Agents for Foreign Patent Solicitors of 323 High Holborn in the
County of Middlesex and 6 Lord Street Liverpool in the County of Lancaster
Engineer for an Invention of "IMPROVEMENTS IN THE METHODS OF AND
APPARATUS FOR SURVEYING LEVELLING AND PLOTTING LAND, communi-
cated to him from abroad by Dr Luigi Cerebotani of Eltville Hof Drais
in the German Empire
PROVISIONAL SPECIFICATION left by the said Alfred Julius Boult at the
Office of the Commissioners of Patents on the 1st December 1882.
ALFRED JULIUS BOULT of the firm of W. P. Thompson & Boult Agents for
Foreign Patent Solicitors of 323 High Holborn in the County of Middlesex and
6 Lord Street Liverpool in the County of Lancaster Engineer
"IMPROVEMENTS
IN THE METHODS OF AND APPARATUS FOR SURVEYING LEVELLING AND PLOTTING
"
LAND [A communication to him from abroad by D Luigi Cerebotani of
Eltville Hof Drais in the German Empire]
This invention relates to improvod methods of and apparatus or instruments for
surveying levelling plotting or the laying off of curves.
The principle which underlays both the construction of the improved instrument
in its various forms and of the various manners of operating with the same (which
constitute the improved methods) will be apparent to mathematicions by the
following diagram and statement.

page_text: A slide embraces the base it has two lugs and a cover-plate and one of the lugs
is brought to bear on the base or box by a spring pressing on the other lug. The
cover plate is cut out and has a transverse slide guided by a screw-arbor. A pivot
pin has its bearing in the small transverse slide; on the lower end of the pin there
is a bolt so mounted that the side turned to the straight edge passes through the
axis of the pivot.
Pinion or other gear is provided for causing motion of the larger slide. The
straight edge is so held between the bolt and spring that it is deflected whenever
the box or base is moved.
The box is fixed on a slide which works on a transverse beam and is adjusted
either by toothed gear or by a spring and screw arrangement
The straight edge carries one telescope and the slide of the base another. In
operating this instrument the central axis of the bolt in the pivot pin is at a
predetermined distance from the base-line and from the zero line. The telescope
on the ruler is directed to the point whose distance is to be ascertained a convenient
object being also sighted with the other telescope and the position of the other
telescopes is noted The slide which embraces the base is then moved to the left;
by this only the telescope on the straight edge is moved; the object first sighted
with the last named telescope is then again brought into its sight and the distance
over which the slide has travelled is noted and from data thus obtained, and by
means of tables that may be previously prepared, the required datum will be
readily found.
In another form there are two telescopes on the straight.edge one at each end,
which are fixed and parallel and a third movable telescope is also provided.
With this form of apparatus the bolt is guided to the end of a convenient
segment of the zero line the sight is taken through one of the fixed telescopes and
the movable telescope directed to the same point so that the two axes meet
therein then the second fixed telescope is made to coincide with the fixed one
and by the data so obtained and by tables previously prepared the desired result
will be obtained.
It is obvious that the construction of the apparatus can be further modified without
departing from the principle of this invention and each modification will require the
operation to be somewhat varied.
In some cases a diopter is used for sighting and may be independent of the
principal apparatus.
The principal part of one form of this apparatus are:
An adjustable beam, two rods, one fixed at one end of the beam the other
movable thereon. At the end of the beam is a diopter a suitable sighting point
being provided for the same. The end of the movable bar may also carry a
diopter for which there is another sighting point the chief data are obtained by
the motions of the movable bar and the scale on the beam for which a sleeve gives
the indications.
This form may also be varied
The controlling telescope may stand either transversely or in the direction of
the object.
The apparatus embodying this invention is to serve for laying off curves or for
measuring elevations it may be constructed as follows.
It consists of two bars which at one end turn on a vertical axis common to both
On the one bar there is mounted a tongue sliding on a sliding piece. A third short
bar turning on the same axis as the other two carries a telescope, in the pin on
which the three bars turn there is a hole into which a diopter is inserted for short
distances. The slide of the tongue carries a sighting point.
At the end of the second bar there is a second sighting point and the whole is
mounted on the table of an ordinary stand.
The arbor or axis of the bars passes through the centre of the round table of the
stand. The bars are graduated and so arranged that they can be fixed in various.
positions by clamps and screws,

page_text: The legs of the stand are hinged so that the instrument can be fixed in an
inclined plane. A fine point on the tongue moves in a groove or center line of the
second bar.
If points are to be found which are equidistant from a centre the distance
between which centre and the operator is known, the following is the operation.
Let two distances be known, that from the observer to the center, and from the
latter to one of the points on the periphery of the circle, the direction of the line
connecting the observer with the centre is known the other direction unknown.
Let the problem be to find. the length and direction of the third line, or the
length for a given direction or vice versa
For this a segment is determined on a strip which is in the direction of the line
between the observer and the centre such segment being of the same proportion to
the tongue as the proportion of the length of the line between observer and centre
and the line between centre and periphery; then straight lines are projected over a.
second lath or strip whose proportion to the distance between the point on which
the bars rotate and the part on the second bar which the tongue marks, as the
radius of the circle to the length of the tongue; thus data are obtained which
allow a circle to be laid off from any stand point whether upon within or without
the periphery; or, by determining the divergence of the two bars in a proper
manner, the direction of a chord may be obtained and by obtaining a number of
chords the whole circle.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, and of
an Order of the Lord Chancellor, filed by the said Alfred Julius Boult in the
Great Seal Patent Office on the 9th June 1883.
ALFRED JULIUS BOULT of the firm of W. P. Thompson and Boult Agents for
Foreign Patent Solicitors of 323 High Holborn in the County of Middlesex and
6 Lord Street Liverpool in the County of Lancaster Engineer "IMPROVEMENTS
IN THE METHODS OF AND APPARATUS FOR SURVEYING LEVELLING AND PLOTTING
"
LAND A communication to me from abroad by Dr Luigi Cerebotani of
Eltville Hof Drais in the German Empire
The distance measuring apparatus heretofore known and used in surveying
have not hitherto proved reliable to such a degreo that the manufacture-and
use of the same, or their principle and construction, could be considered as
completed.
Now the present invention relates to a process whereby by means of simple
instruments distances can be determined and curves laid off in an elementary
trigonometric manner without the calculation of angles and without the use of a
nonius, with an accuracy not heretofore obtained by any instrument and which is
rendered possible solely by this method
In the annexed drawings the instruments required for the process are
represented in several forms which however are all based on the same principle
Figures 1. 2. and 3 represent top views of three different modifications of the
apparatus
SU Figure 1 is a box In this box (or in any base which will answer the
same purpose) there is lengthwise a ruler L capable of rotating on b that is to say
round a point in a straight line passing over the edge of the ruler. The latter is
by means of a spring held towards the left. D is a slide passing round the box
this slide is constructed as follows
Figure 1, 3 and 5 show a cover plate and two lugs surrounding the box; one of
the lugs takes conically upon the box by means of a spring pressing against the
other lug In the coverplate which is cut out there is also a transverse slide 8.
Figure 1 which is guided by a screw spindle operated at y in a groove; the details
hereof are shewn in Figure 6
In this small slide a round pivot pin has its bearing, on the lower end whereof a
bolt is so mounted that the side turned towards the ruler or straight edge passes
through the axis of said pivot (Figures 7 and 8)
To cause the requisite movement in a straight line of the large slide D a pinion is
provided underneath the box (Figures 1. 4. 5) Only the straight edge is held
between bolt and spring so that the same is deflected at every, even slight, forward
or rearward motion of the box, viz of the central axis of the bolt which is outside
the zero point (Figure 8)
The zero point is the straight line passing through the axis of rotation 61 of the
guiding line
The box US rests immoveably on a slide R (Figure 4) the latter (and con-
sequently the box US) is moveable in a straight line on the transverse beam
A B either by means of a pinion or by pressure of a strong spring and a
bolt (side view figure 4) On the ruler L lays immovably the principal
telescope F and on the slide T. R the controling telescope C in such a manner
however that the optical (visual) axis of the former passes through the axis of
rotation of the ruler that of the latter being parallel with the line in which T R is
guided

page_text: The whole is carried by a stand (figure 4) which is capable of being adjusted
at will
The operation is as follows. The central axis of the bolt is at a fixed distance
from the basis line 10-30% (and at a conveniently chosen magnitude
(1. 30. / from the zero line) this is the object of the transverse lines on the
coverplate
ת
The instrument is so adjusted that whilst the principal telescope is directed
towards the object whose distance is to be calculated some other object which is
to observed is in line with the controlling telescope C. By F (adjusted from
the stand) the point under consideration is sighted It is then ascertained and
carefully noted what point the visual axis of the controlling telescope strikes
The slide D is then moved any convenient magnitude (say 1-30 /m) it then is at
once to be ascertained through the controlling telescope whether the visual axis
has deviated and if so it is corrected (by adjustment at the stand); the slide T. R
(and thereby both telescopes) are moved to the left on the beam AB so that C does
not in the least get out of the sight line and if necessary it is brought back to the
same; then the visual axis of F which has deviated is again brought in line with
the point under consideration The path covered by this sliding action on the
beam A B which is by preference metrically graduated is read and by referring
to previously prepared tables, the distance will be directly found allowance being
made for the predetermined distance of the central axis of the bolt from the zero
line as well as from the basis line and of the extent of the first movement of the
slide D.
Figure 9 represents the progress of the operation F, F¹. F" are the three
different positions of the principal telescope m and m³ the central axis of the bolt
in the first and in the second place or position
Let the triangle dm³ B be considered. From the known magnitude dB, dm¹
and mm, m.p obviously arises. By sliding F¹ to F the upper side P. V is
ascertained (A B || mp) then from the known elements the triangle P. B. V as well
as the triangle A. P. B are obtained vis the value of PB
=
P. B (P. V. x B. m): mp or as mp = A, B-nm and in accordance with a
known principle P. B = (A. B × Bm): A. B, — n m
1
The apparatus in Figure 2 consists
1) of the box, the ruler (turning on 6) and the slide as in Figure 1
2) of the two principal telescopes I and ƒ fixed on the two ends of the ruler
transversely, parallel to one another and immovable
3) of a controlling telescope C which is adjustable at will
Operation A convenient section of the zero line (from b) is determined to the
end of this section, the central axis of the bolt is guided, the sight is taken
through F (adjustment at the stand) to the point in question. Towards the latter
the controlling telescope C is directed by the gearing provided for it, so that the
two axes of F and C meet in the same point. Then one looks throug f. moving
the slide D till the thread cross of f coincides with the point under consideration;
one then looks through C to ascertain whether any, even slight, irregularity has
taken place viz whether it has deviated from the sight line if so this is
corrected, then look again through f and so on; when C and ƒ correspond the
operation is completed
By means of tables prepared before hand the sought distance is at once read
allowance being made: a) for the chosen section of the zero line from b.-b) for the
distance (difference) between the zero line and the line of guidance; c) of the path
traversed by the slide D.
.
·

page_text: For instance if the box (viz the straight line between the visual axis of F
and f) is ½ m, and if the difference is 1'm the section that was chosen
being 30% the path traversed 4 m/m we obtain:
Distance 5662.5 M
月
Figure 10 shows the progress of the operation, it is nothing but a modification
of Figure 9 and will readily be understood by those conversant with the subject
The calculated parallel to the zero line is not, it is true, strictly and simply the
operative difference which has to be taken into consideration (of the ruler edge
deviating from the zeroline by one or at most 2 /m) but the difference is so insig-
nificant so slight that the error arising from it need not be taken into
consideration
The apparatus figure 3 differs from the one described in its construction in the
following points
{
i
1) the telescope f is rigidly fixed on the box and not on the ruler
2) F and ƒ are parallel with one another only when the ruler is in the direction
of the zero line
3) there is no controling telescope, f being the means for controling also
Operation First the point in question is first sighted through f(adjustment at
the stand) then one looks through F and D is moved till the thread cross coincides
with the point in question; then look through f to ascertain whether it has been
disturbed correct if required (viz if deviated from the sight line) turning at the
stand and so on; observe distance of central axis of bolt from point of rotation of
ruler b and read distance from tables prepared beforehand.
Figure 11 illustrates the progress of operation
To render the matter more clear and to obviate mistakes the following may be
mentioned
I) The object of the deviation of the transverse line (viz the ruler) is not to
ascertain the small angle but the ascertaining of the operating parallel lines and
of the proportionate lateral sections or basis sections (as the case may be) for any
triangle
II) The operating difference with the apparatus figure 3 is the difference in the
instrument itself whilst in apparatus figure 2 it is only a fraction thereof
III) With figure 2 the operation begins with the "sighting" of F; in figure 3
with the sighting of f
IV) With figure 3 the distance is directly proportionate to the movement of D
to the left; with figure 2 it is universely proportionate thereto
V) In apparatus and proceeding figure 2 the separate controlling telescope may
also be dispensed with by fixing F immovably on the box and so arranging it that
both telescopes F and fare parallel to one another when the central axis of the
bolt is at a determined distance from the zero line as well as from the point of
rotation (b) of the ruler. If however such is the case then there is for the use of
the instrument only one and the same primary section, one and the same primary
difference the magnitudes to be considered (which form the basis) are always the
same otherwise the proceeding is the same the telescope F remains fixed of course
and serves as controling telescope also.
. VI) The sliding of D has for its object in Figure 3 the determining of the lateral
section in Figure 2 of the difference or section of the basis
VII The power of the apparatus shown in figure 2 is far superior in comparison
to that shewn in Fig 3. If for instance caeteris paribus with the apparatus and
operation figure 3, distances up to 1000 meter can be calculated, the apparatus and
operation Figure 2 will allow distances of 10, 20 and more Kilometers to be
determined
VIII "If however apparatus Figure 3 is so constructed that the telescopes
" become parallel when the central axis of the bolt is not in the zero line but in
a predetermined point in the basis line whose distance from the zero line is also
predetermined, then a most important essential change takes place."
«
T
"The operation remains the same; first f is (by turning at the stand) turned

page_text: "from D to P. and then F &c. but from this sliding motion another difference is
now formed and comes into consideration which is only a small fraction of the
" difference upon which the instrument is based, as in Figure 2, its power is
"therefore increased, nay caeteris paribus is even much greater than in Figure 2
as the point in the guiding line in which parallellism occurs may be assumed to
"be quite at the top or even outside the instrument (in the projection of the
guiding line). The above mentioned slight error does not occur here at all, as
"the difference to be considered is here the actually operating difference."
Figures 13 13 13b show in perspective and plan an instrument in which the
sighting is effected by a diopter and the aiding apparatus can be independent of the
principal apparatus and at any distance therefrom
"
Figures 14. 14 and 14b show the construction of an instrument as described at
Figure 13. but with that difference that instead of the diopter telescopes are used.
Figure 15 shows in plan a modification of this apparatus shewn in Figures 13.
13. 13b, 14. 14. 14b. The principal parts of the same are as follows: A beam
S. U adjustable at will; two rods A. B. C. D whereof one fixed at U the other
being moveable by means of gearing or screw to and fro over U, S. similarly to what
is shown in Fig 5. At A there is a diopter with a corresponding "sighting point"
at m, these are arranged exactly as shown in Figs. 27 and 28. Upon the straight
line connecting the diopter A and the point of m no deviation takes place by
displacing C. D. In D there is likewise a diopter and for this n is the sighting
point now the length of the straight line mn is that of A B (viz the straight
line connecting the diopter) less d. B (that is to say the difference) so that B. n
(the side section) deviates from the sight line at any forward or rearward movement
of C. D however small this may be The operation is obvious from the construction
and the distance to be found can be read directly on the beam U S. through the
displacement of C. D
Figure 16 shows a modification of the instrument shewn in Figures 13 and 14;
in this the basis line lays transversely in the same path with the side section
Figures 17 and 18 show modifications of the apparatus shewn in figure 16 in
perspective and these differ from the latter only by details of construction which
need no description.
Figure 19. perspective view of an instrument in which the side section is constant,
the operating difference being produced at will.
Figure 20 differs in construction from 19 only in that, that the controling
telescope is not placed transversely, but in the direction of the object itself and is
provided with a device for adjusting it at will
The Figures 21-34 show an apparatus for laying off curves based on the same
principle. Figure 21 is a perspective view of the same when used for measuring
elevations and depressions whilst
Figure 22 shows the same as a curve measurer in horizontal position,
Figure 23 top view of the instrument,
Figure 24 side elevation thereof,
Figure 25 transverse section on ab Figure 23,
Figures 26-30 details of detached parts;
Figure 31-34 explanations for the use of same;
The instrument consists of two bars. A'. B' and A¹. C. (Figures 23, 24, 25, 29 and
30) which at one end turn on a vertical axis A¹. common to both, in one plane. On
the bar A'. B' there is mounted a tongue m. n sliding on the sliding piece D'. A
third short bar A¹ F¹ (Figure 23) also turning on A¹ carries a telescope for sighting
the directions. For short distances the diopter, Figure 28, is used in sighting
and for this purpose it is inserted in a hole in the centre of the bolt A¹
Figure 23.
The slide D¹ on bar A¹ B¹ carries the sighting point 0¹ (Figure 27) required for
this purpose in the axis of rotation of the tongue
In like manner the bar A' C' has at the end point C² a sighting point. This
imple instrument is mounted on the table of an ordinary stand

page_text: The axis A' of the bar's passes through the centre of the round table G (Figure
23., 24 and 25) The bars are, as shewn in Figures 23, 29, and 30, provided with
metrical scales and moreover so arranged that they can be fixed by clamps and
screws H (Figures. 29. 30) in any position in the plane in which they move.
The legs of the stand move on hinges so that if required the table or the
instrument can be readily be adjusted in an inclined plane.
Lastly on the tongue m n (Figure 23) a fine point is provided, which for the
purpose of accurate setting is guided in the groove or center line of A¹. C.
The instrument is used in the following manner
From the end point A of a straight line AO of given length and direction
( Figures 31. 32. 34) points (P¹. P¹¹. Pш) are to be found which are at a
predetermined distance from the other end point O which may be inaccessible or
even invisible (O. P. = 0 P¹. O. P¹¹ O. P¹¹¹)
In other words therefore, lot two sides A O. O. P be given and also the direction
of AO, or let them be known by previous calculation, whilst the direction of the
straight line O. P is unknown
Now let the length and direction of the third (AP, A P¹. A P") or the length
corresponding to a given direction (and vice versa) be what is to be determined
For the solution of this problem a segment Am is determined from the
inaccessible point upon the strip AB lying in the direction AO which segment
bas the same proportion to the tongue mn (viz to that line which-whatever its
position may be is always parallel to the opposite side by reason of the conditions
previously fulfilled) as AO to O. P
O P
972 92
When this has been done it will only be necessary to project straight lines over
the second bar A. O whose proportion to An is as O.P to mn, therefore equal
to the product from the constant quotient and the arbitrary segment tNo
The ends of these straight lines are the points P P' P... which were to be found
Therefore a circle can be laid off from any stand point whether upon, within or
without the periphery by considering the radius to the known base of a triangle
whose apex is the stand point, one side being the straight line from the standpoint
to the centre and the other side the distance to be found by the proportional
segments.
.
The end points of the latter then give points of the periphery in question.
Should however this operation viz the drawing of straight lines from one stand
point to the curve to be constructed not be easy to carry out or even
impossible as for instance in railways going up on mountains or in tunnelling then,
on the ground of what has been said, it will be feasible to determine (an
appropriate divergence of the bar AC assuming the direction of the chord
(Fig 34) and of the bar A B which takes the position of the radius being
chosen) the length of the said chord corresponding with the circle or vice versa.
The curve is then laid off by tracing a series of chords of equal leng the
constant divergence which is either predetermined or obtained being carefully
kept in view
Figure 12 illustrates the planimetric principle underlying the described
apparatus and its operation viz.
A. P: An AB: AB-n m, or
AP: dm A, B:d-B
Having now described the nature of the said Invention and the manner of
performing the same as communicated to me by my foreign correspondent I wish
it to be understood what I claim and desire to protect under the hereinbefore in
part recited Letters Patent is
The method of surveying, viz a distance measuring apparatus in which the
planimetric principle underlying the same
AP: An AB: AB-n m, or
D An
101
A the fallawing manner

page_text: connecting the diopter and the sighting point) is free to rotate on one of its ends
and can be deviated by a point (this point is the central axis of the bolt or of the
sighting point and is moved up and down along a straight line m which is at a
certain distance from the said point of rotation and has a given direction) in such
a manner that the said transverse line by such deviation assumes the position of
one side of the triangle which is to be considered, the other sides thereof being
previously determined or produced.
2 That of the three magnitudes A B, d B, d m (by which A P is obtained) two
are either given or set out arbitrarily, whilst the third results from the operation
in the following manner
a) The side segnent d m (=An) by sliding the central axis of the bolt m
passing over the guide line (the distance whereof from the zero line is a given
magnitude and which is metrically graduated) vis by deviating the ruler
(Figures 3, 11) until the telescope fixed on the latter assumes the requisite direction
and so on substantially as set forth
b) The base line A B is obtained (the small fraction of the distance between
guide line and zero line which now is the difference to be considered, having first
been arbitrarily determined and not the whole of such distance) by sliding the
telescope which has been deviated from the sight line (Figures 1 and 9) towards
the left and so on, substantially as set forth
c) The difference d B (that is to say a fraction of the difference underlying the
instrument) is obtained by sliding the central axis of the bolt further away from
the extremity of a predetermined segment (Figure 2 and 3 as also "3" if arranged
according to § VIII) or by deviating the ruler till the telescope fixed on it free
end (in Figure 3 on the point of rotation). assumes the required direction
3) The method of producing from any standpoint and by means of the
apparatus for laying off curves (Figure 23, 24, 25) proportionate sections of the
triangles in question and thus determining the unknown position and length of
the same and consequently also ascertaining the points to be marked off without
the calculation of angles and co-ordinates in the matter set forth
4) The construction of the instrument for plotting out curves (Figures 23. 24. 25)
consisting of the bars A'. B. and A'. C. capable of rotating on the vertical axis is A¹
in combination with a tongue m n capable of rotating on the slide D₁ (Figure 1)
with the telescope fixed on the bar A' F' and capable of rotating round A or with
the diopter and in combination with an ordinary stand in the manner set forth
In witness whereof I the said Alfred Julius Boult have hereunto set my
hand and seal this ninth day of June in the year of our Lord One thousand
Eight hundred and Eighty three.
ALFRED J. BOULT (L.S.)