Improvements in Instruments for Determining the Distance and Height of Inaccessible Objects and for Measuring the Width thereof.
Year: 1897

page_text: Date of Application, 17th June, 1897
Complete Specification Left, 16th Mar., 1898-Accepted, 17th June, 1898
PROVISIONAL SPECIFICATION.
Improvements in Instruments for Determining the Distance and
Height of Inaccessible Objects and for Measuring the Width
thereof.
I, MICHAEL HORNSTEIN, of 17, Wahringerstrasse, Vienna, IX Austria, Gentle-
man, do hereby declare the nature of this invention to be as follows:-
This invention relates to an instrument by means of which the distance, eleva-
tion, height and width of a visible object can be determined from a single
standpoint, without the said object being necessarily accessible. In determining
the distance of a point, that is to say, determining its position or location, in all
cases two sights must be taken. In working with range finders, universal measur-
ing instruments, theodolites, tacheometers, etc., these two sights are made from
one standpoint over two horizontal threads, whose projections are read off from a
vertically divided lath which is set up on the point to be observed. In working
with the measuring table and in triangulation sights are taken successively from
two standpoints.
Range-finders have already been proposed in which the triangle necessary for
finding the distance of inaccessible points is formed from a single stand point.
In most of these instruments the points from which the two sights are taken
are situated in a line at right angles to the first sight, so that this triangle is a
right-angled triangle, for determining which two known valves are sufficient.
When the inclination of the sights to each other is predetermined, only the distance
of the two starting points for sighting must be measured. But when this
distance is fixed, it is sufficient to measure the angle enclosed by both sights in
order to find the distance of an inaccessible point.
These instruments however, which require two telescopes or other sighting
devices have great drawbacks; they are not directly capable of being used for
finding the elevation and then they only determine the. actual horizontal distance
of the stand point from the point observed when both points are on the same level.
In all other cases the determined distance is merely the length of the air line
between the two points, and is not the projection of this air line upon the hori-
zontal plane which is of importance in all measuring work.
Other instruments proposed for the like purpose, have a single telescope through
which sights are taken successively from two points situated vertically over each
other, and which are situated at a predetermined invariable distance from
each other. On account of the great length of their vertical base, these instru-
ments necessitate special means of transport and aids to observation, which must
be made from such a great height above the ground that ladders or the like are
necessary.
In an instrument according to this invention, the above mentioned drawbacks
are obviated. Both sights are taken by means of one and the same telescope which
is capable not only of a vertical, and a horizontal rotary motion, but can also be
moved in a vertical direction to an extent which can be measured and which varies

page_text: in each case.
The alteration in the height of the instrument produced by this
movement is relatively small and is measured as accurately as possible,
because it serves as the basis for finding the distance and the elevation of the
observed point, in addition to the inclinations of the sights. The amount of the
sight inclination is preferably read off from a fixed scale with the aid of a pointer
which moves with the telescope. For the purpose of measuring the width of an
object, such as, for instance, the diameter of a trunk of a tree at a known distance
above the ground, an apparatus may be employed for measuring the angle enclosed
by the sight towards one bounding edge of the object, and the sight towards the
other edge.
A vertical thread arranged in the telescope is first caused to coincide
with the one edge and then with the other edge of the object to be measured. The
amount of the horizontal movement of the sighting tube rendered necessary for
this purpose can be read off, in order to serve, in combination with the previously
known distance of the object, for the determination of its width.
Suitable arrangements of the measuring scales may be made so as to reduce to
an extremely small amount the work of calculation for all these determinations,
so that even inexperienced persons are able to obtain exact results of observation.
The accompanying drawings illustrate by way of example a form of instrument
constructed according to this invention.
Fig. 1 is a side elevation of the same.
Fig. 2 is a horizontal section on the line - and
Fig. 3 is a similar section on the line y-y of Fig. 1.
The sighting tube marked a must not be a telescope in all cases. A sighting
tube having an eyepiece of the smallest possible size, is suflicient for measuring
small distances. The water-level a serves for the horizontal adjustment of the
sighting tube, on the eye piece of which there is provided cross-threads, which in
those cases where it is not required to determine the location of the observed points,
can be replaced by a horizontal thread or by two horizontal threads,
situated one above the other, between which the observed point is viewed.
In the example shown, a folding telescope is employed, the cradle a² of which is
vertically movable in a forked bearing in the usual manner. To the latter there
is fixed by means of arms a³ a scale a which, in the arrangement shown, is set
horizontally when the instrument is properly set up; it may, however, have any
other desired position. The unit of measurement of the scale is in a definite ratio
say 1: 1000, to its vertical distance from the centre of rotation of the telescope.
A lever a pivotted on the telescope cradle a³, moves with the telescope along the
scale a¹.
In the instrument as shown, the arrangement is such that this lever is moved
by means of a screw mechanism, hereinafter described, along the scale, the tele-
scope moving with it. This arrangement having for object to enable the sighting
tube to be moved exactly to an extent corresponding to the unit of measurement
of the scale or to a multiple of said unit, which is of great advantage for reasons
hereinafter stated.
In addition to this vertical movement the telescope is also capable of a hori-
zontal movement as in usual universal measuring instruments, by making the
round supporting spindle 6 of the telescope cradle a capable of rotating. The
amount of this horizontal movement is read from a fixed disc b¹ (divided in degrees)
by means of a nonius 62 working thereon, the nave-portion 63 of which
can be made fast to the supporting spindle 6 by means of a clamp 64. The hori-
zontal movement is effected by means of a device of a well known kind. The
simplest and most used means in universal measuring instruments is by the use
of a screw whose screw-threaded portion passes through a nut pivoted to the
fixed disc b', whilst the smooth bolt portion of the screw is jointed to an arm 65
fixed to the nave-part 3, as shown in Fig. 2.
Instead of the device described, any other desired device may be employed,
such as, for instance, a screw mechanism of the kind described with reference to the
scale a

page_text: As stated at the commencement of this description, the telescope a must
also be capable of vertical movement or of an adjustment in height parallelly to
itself. This is effected, in the example shewn by causing the supporting spindle b
of the telescope to form an upper extension, of a three-sided prism d, which is
movable vertically in a correspondingly recessed sleeve f. This sleeve is arranged
vertically with relation to a carrying plate f¹, which is fastened by means of hooked
screws wound round with spiral springs, to the table plate f³ of the standard f*,
in such a manner that an exact horizontal position of the carrying plate f¹ is
possible of attainment when the screws f² are tightened up. For this purpose
three adjusting screws f³ and spirit levels f and fare employed in the usual
way. For raising or lowering the prism d there is used a toothed rack d¹ which
is formed on one side of said prism and in which gears a toothed wheel g¹
keyed on a shaft g. This shaft rests in bearings g³ fixed on the carrying plate f¹,
and carries at both ends hand wheels g³ by means of which the shaft 9 can be
rotated, and consequently the prism d be moved vertically within the sleeve f
The amount of this vertical movement is read off from a disc g (which is provided
with a scale or with divisions, and is clamped upon the shaft 9,) by means of a
nonius g which is fixed on a fixed part (for instance on one of the bearings g³).
Instead of the arrangement described for vertical adjustment, any other device
for the same purpose may be employed, for instance instead of a prism, there
might be employed a screw spindle which is raised and lowered by means of a crank
handle mechanism with toothed wheel gearing.
Since the correctness of the vertical adjustment depends on the accuracy of the
vertical movement, it is advantageous in many cases to provide a micrometer
arrangement of known type, for the purpose of effecting the minute adjustment after
the rough or approximate adjustment effected by means of the device described.
To that part of the instrument which carries the telescope u and which is capable
of being raised and lowered, there is fixed a spirit level as which acts when this
part of the instrument is in a vertical position and thus indicates in all cases
whether said part has remained in a vertical position after the vertical adjustment
has been effected. According to the indication of the spirit level, the instrument
is again rendered vertical by means of the three screws f5, whereby an otherwise
unavoidable error of observation is obviated. According to the preceding, the
telescope is capable of three movements, viz:-1, of a rotary movement in the
vertical plane passing through its longitudinal axis;
2, of a rotary movement in the horizontal plane;
3, of a vertical or height adjustment up or down parallel to itself.
Further arrangements of the instrument will be described hereinafter in describ-
ing the mode of working.
Let B (Fig. 4) be a point of an object the distance E of which from the stand
point A of the instrument is to be measured.
The telescope a (the instrument being at a height J, position 1) is pointed to-
wards the point B; the lever a turning with the sighting tube and assuming a
position in which a reading m is indicated on the scale a. Then the sighting
tube is raised (or lowered) to an extent V, and then turned until the point B is
again sighted. The reading m¹ is now taken in this position (position 2) from
the scale. There are now the following relations:-

page_text: In order to obviate all calculation, it is arranged that m-m 1. If now as
above stated, the unit of measurement of the scale is a bath of its distance from
the centre of rotation of the sighting tube, then = 1000 and E 1000 V: there-
fore every millimetre of the amount of the vertical movement V corresponds to
one metre of the desired distance E, so that the divided disc can be easily so
arranged as to enable the distance to be read off from it directly.
Then according to the above the manner of working will be as follows:-
In position 1 the point B is sighted with the pointer lever in the position m.
Then the telescope is turned so as to bring the pointer lever into the position m-l.
The telescope is raised or lowered until the line of sight at this latter inclination
of the telescope again meets the point B, and then the amount of this vertical
movement is read off.
screw
For the purpose of enabling the telescope to be turned to a definite extent, the
hereinafter described arrangements are provided in the instrument shewn, viz.
Parallelly to the bar that carries the scale a³, there is pivoted a
spindles which acts upon the pointer lever a5. This spindle carries on its free
end facing the observer a hand wheel s¹, the divided periphery of which slides
along a fixed nonius s*, and extends through a sliding carriage s², which must
move along the scale bar when the hand wheel is rotated. The sliding carriage 2
carries a sliding piece 3 which is capable of being slidden parallel to the scale
by means of a micrometer screw st, and has an index a7 against which the pointer
lever a is constantly pressed, for which purpose there is employed in the arrange-
ment shown a small rod s which acts upon the back of the pointer as and which
is subjected to the influence of a spring situated in the casing s6.
If now for instance, the vertical distance of the scale from the pivot of the
pointer lever is 200 millimetres, then, with the ratio of division of 1: 1000, the
unit of measurement is equal to 0.2 millimetres. Therefore if the divisions of
the scale are 5 millimetres apart, this distance corresponds to 25 units of measure-
ment. In such case the screw 82 is made preferably with a pitch of 5 m/m, so that
each complete revolution corresponds to the shifting of the index on the scale from
one division to the other; the micrometer screw 84 is made with a pitch of 0.2 m/m
so that each of its revolutions corresponds to a shifting movement to the extent
of one unit of measurement. Thus if, in the position 1 of the instrument, the
telescope has been directed on to the point B, it is then merely necessary to turn
the micrometer screw s¹ once round, to shift the telescope vertically, until the sight
again meets the point B, and then to read off from the disc g the amount of this
shifting movement. In order that a revolution of the micrometer screw s may
be effected with exactness, it is provided with an index, and may further carry
a spring tooth or the like, which snaps into a recess in a sleeve after each revolu-
tion. In order that it shall not be necessary to read off from the disc g both
before and after the vertical movement of the telescope the arrangement is prefer-
ably such that the disc can be set each time at zero, for which purpose it must be
mounted loosely, but so as to be capable of being clamped fast, on the shaft g.
The number of its complete revolutions during the raising or lowering of the

page_text: telescope is read off from a counting or registering device of usual construc-
tion which is, not shown.
For the purpose of more convenient manipulation of the instrument, it is advis-
able to arrange the scale at with the entire screw mechanism s to s, not above, but
below the telescope. The former mode of construction was chosen on account of
the greater ease of illustration.
II. LEVELLING AND DETERMINING HEIGHTS AND DEPTHS.
m
In the above worked out equation H
E H, as shown in Fig. 4, represents
τ
directly the difference in height between the observed point B and the level of
the axis of the turning movements of the telescope. Consequently it is merely
necessary to multiply the number read off in position 1 from the scale a, and
the hand wheel s¹, with the number read off from the disc g, in order to obtain
this difference in height. On adding this difference to the height J of the instru-
ment (which height is to be measured directly), there is obtained the difference
in the levels of the two points a and b. In some cases it may be advisable to
sight a point of given height (for instance when it is desired to determine as
hereinafter described the width of the trunk of a tree at a known height). In
such a case, by means of the equation H
=
m
E, and the known valves H and E,
the unknown valve m can be determined, and then there is obtained that number
upon which the hand a' of the pointer lever a5 must be set in order that the
telescope shall have the inclination at which the line of sight meets the object
at the desired height. If the quotient of this division is not a whole number or
is not such a number to the fractions of which the hand of the pointer lever can
be set by means of the nonius provided then the height of the instrument is
altered as required by raising or lowering the telescope.
III. DETERMINATION OF WIDTH AND THICKNESS.
As stated at the beginning, the measurement of width can be effected by means
of a vertical thread fixed in the telescope, which thread is caused to coincide
first with one and then with the other edge of the observed object. When the
distance of said object is known, and the horizontal turning movement of the tele-
scope is measured, the width is easy to determine. Instead of reading off the
angular measurement of this horizontal turning movement from a divided circle
on the horizontal disc b¹, it is preferable to use a tangent scale similar to the
scale used for the vertical turning movement. The scale must of course be
horizontal. The pointer lever (which is then also horizontal) for this scale need
not be arranged so as to be constantly turned with the telescope, but is preferably
clamped fast to a part (turning horizontally with the telescope) only when measure-
ments of widths are to be effected. As this arrangement will be readily understood
without further trouble, from the description of the tangent scale a' for the vertical
turning movements of the sighting tube, the said arrangement is not illustrated.
As will be understood from the preceding distances, levels, of in-
accessible points, and also the heights and widths of inaccessible objects, can be
determined from the stand point of the instrument, by means of said instrument
as described without the necessity of making complicated calculations, so long as
such inaccessible points are visible.
1
T
1007
F. WISE HOWORTH,
46, Lincoln's Inn Fields, London, W.C.,
Agent for the Applicant.

page_text: Improvements in Instruments for Determining the Distance and
Height of Inaccessible Objects and for Measuring the Width
thereof.
I, MICHAEL HORNSTEIN, of 17, Wahringerstrasse, Vienna, IX. Austria, Gentle-
man, 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 relates to an instrument by means of which the distance, eleva-
tion, height and width of a visible object can be determined from a single
standpoint, without the said object being necessarily accessible. In determining
the distance of a point, that is to say, determining its position or location, in all
cases two sights must be taken. In working with range-finders, universal measur-
ing instruments, theodolites, tacheometers, etc., these two sights are made from
one standpoint over two horizontal threads, whose projections are read off from a
vertically divided lath which is set up on the point to be observed. In working
with the measuring table and in triangulation, sights are taken successively from
two standpoints.
Range-finders have already been proposed in which the triangle necessary for
finding the distance of inaccessible points is formed from a single stand point.
In most of these instruments the points from which the two sights are taken
are situated in a line at right angles to the first sight, so that this triangle is a
right-angled triangle, for determining which two known values are sufficient.
When the inclination of the sights to each other is predetermined, only the distance
of the two starting points for sighting need be measured. But when this
distance is fixed, it is sufficient to measure the angle enclosed by both sights in
order to find the distance of an inaccessible point.
These instruments however, which require two telescopes or other sighting
devices have great drawbacks; they are not directly capable of being used for
finding the elevation i.e., heights of positions and then they only determine the
actual horizontal distance of the standpoint from the point observed when both
points are on the same level. In all other cases the determined distance is merely
the length of the air line between the two points, and is not the projection of this
air line upon the horizontal plane which is of importance in all measuring work.
Other instruments proposed for the like purpose, have a single telescope through
which sights are taken successively from two points situated vertically over cach
other, and which are situated at a predetermined invariable distance from
each other. On account of the great length of their vertical base, these instru-
ments necessitate special means of transport and aids to observation, which must
be made from such a great height above the ground that ladders or the like are
necessary.
In an instrument according to this invention, the above mentioned drawbacks
are obviated. Both sights are taken by means of one and the same telescope which
is capable. not only of a vertical, and a horizontal rotary motion, but can also be
moved in a vertical direction to an extent which can be measured and which varies
in each case. The alteration in the height of the instrument produced by this
vertical movement is relatively small and is measured as accurately as possible,
because it serves as the basis for finding the distance and the elevation of the
observed point, in addition to the inclinations of the sights. The amount of the
sight inclination is preferably read off from a fixed scale with the aid of a pointer
which moves with the telescope. For the purpose of measuring the width of an

page_text: object, such as for instance, the diameter of a trunk of a tree at a known distance
above the ground, an apparatus may be employed for measuring the angle enclosed
by the sight towards one bounding edge of the object, and the sight towards the
other edge. A vertical thread arranged in the telescope is first caused to coincide
with the one edge and then with the other edge of the object to be measured. The
amount of the horizontal movement of the sighting tube rendered necessary for
this purpose can be read off, in order to serve, in combination with the previously
known distance of the object, for the determination of its width.
Suitable arrangements of the measuring scales may be made so as to reduce to
an extremely small amount the work of calculation for all these determinations,
so that even inexperienced persons are able to obtain exact results of observation.
The drawings filed with my Provisional Specification illustrate by way of
example one form of instrument constructed according to this invention. Fig. 1
is a side elevation of the same. Figs. 2 and 3 are horizontal sections on the
lines xx, and y y respectively of Fig. 1.
The sighting tube marked a need not be a telescope in all cases. A sighting
tube having an eyepiece of the smallest possible size, is sufficient for measuring
small distances. The water-level a serves for the horizontal adjustment of the
sighting tube, on the eyepiece of which there is provided cross-threads, which, in
those cases where it is not required to determine the location of the observed points,
can be replaced by a horizontal thread or by two horizontal threads,
situated one above the other, between which the observed point is viewed.
In the example shown, a folding telescope is employed, the cradle a of which is
vertically movable in a forked bearing in the usual manner. To the latter there
is fixed by means of arms a³, a scale which, in the arrangement shown, is set
horizontally when the instrument is properly set up; it may, however, have any
other desired position. The unit of measurement of the scale is in a definite ratio
say 1 1000, to its vertical distance from the centre of rotation of the telescope.
A lever a pivotted on the telescope cradle a², moves with the telescope along the
scale a*
In the instrument as shown, the arrangement is such that this lever is moved
by means of a screw mechanism, hereinafter described, along the scale, the tele-
scope moving with it. This arrangement has for object to enable the sighting
tube to be moved exactly to an extent corresponding to the unit of measurement
of the scale or to a multiple of said unit, which is of great advantage for reasons
hereinafter stated.
In addition to this vertical movement, the telescope is also capable of a hori-
zontal movement, as in usual universal measuring instruments, by making the
round supporting spindle 6 of the telescope cradle a³ capable of rotating. The
amount of this horizontal movement is read from a fixed disc 61 (divided in degrees)
by means of a nonius or vernier 62 working thereon, the nave-portion 3 of which
can be made fast to the supporting spindle 6 by means of a clamp 6. The hori-
zontal movement is effected by means of a device of a well known kind. The
simplest and most used means in universal measuring instruments is a
whose screw threaded portion passes through a nut pivoted to the fixed disc ',
whilst the smooth bolt portion c¹ of the screw is jointed to an arm 65 fixed to the
nave-part 63, as shown in Fig. 2.
C
screw
Instead of the device just described, any other desired device may be employed,
such as, for instance, a screw mechanism of the kind described with reference to the
scale a*. As stated at the commencement of this description, the telescope a must
also be capable of vertical movement or of an adjustment in height parallel to
itself. This is effected, in the example shown, by causing the supporting spindle b
of the telescope to form an upper extension of a three-sided prism d, which is
movable vertically in a correspondingly recessed sleeve f. This sleeve is arranged
5 vertically with relation to a carrying plate f1, which is fastened by means of hooked
screws wound round with spiral springs, to the table plate 3 of the standard f,
in such a manner that an exact horizontal position of the carrying plate fl is

page_text: possible of attainment when the screws f are tightened up. For this purpose
three adjusting screws f5 and spirit levels fo and f7 are employed in the usual
way. For raising or lowering the prism & there is used a toothed rack d which
is formed on one side of the said prism and in which gears a toothed wheel g¹
keyed on a shaft g. This shaft rests in bearings g² fixed on the carrying plate f¹,
and carries at both ends hand wheels g3 by means of which the shaft
g can be
rotated, and consequently the prism d be moved vertically within the sleeve f.
The amount of this vertical movement is read off from a disc g (which is provided
with a scale or with divisions, and is clamped upon the shaft g) by means of a
nonius g³, which is fixed on a fixed part (for instance on one of the bearings g²).
Instead of the arrangement described for vertical adjustment, any other device
for the same purpose may be employed, for instance instead of a prism, there
might be employed a screw spindle which is raised and lowered by means of a crank
handle mechanism with toothed wheel gearing.
Since the correctness of the vertical adjustment depends on the accuracy of the
vertical movement, it is advantageous in many cases to provide a micrometer
arrangement of known type, for the purpose of effecting the minute adjustment after
the rough or approximate adjustment effected by means of the device described.
To that part of the instrument which carries the telescope a and which is capable
of being raised and lowered, there is fixed a spirit level as which acts when this
part of the instrument is in a vertical position, and thus indicates in all cases
whether said part has remained in a vertical position after the vertical adjustment
has been effected. According to the indication of the spirit level, the instrument
is again rendered vertical by means of the three screws f5, whereby an otherwise
unavoidable error of observation is obviated.
According to the preceding, the telescope is capable of three movements, viz. :-
1, of a rotary movement in the vertical plane passing through its longitudinal
axis;
2, of a rotary movement in the horizontal plane;
3, of a vertical or height adjustment up or down parallel to itself.
Further arrangements of the instrument will be described hereinafter in describ-
ing the mode of working.
I. MEASUREMENT OF DISTANCES.
Let B (Fig. 4) be a point of an object the distance E of which from the stand
point A of the instrument is to be measured.
The telescope a (the instrument being at a height J, position 1) is pointed to-
wards the point B; the lever a turning with the sighting tube and assuming a
position in which a reading m is indicated on the scale at Then the sighting
tube is raised (or lowered) to an extent V, and then turned until the point B is
again sighted. The reading m¹ is now taken in this position (position 2) from
the scale.
There are now the following relations:-

page_text: In order to obviate all calculation, it is arranged that mm' = 1.
If now as above stated, the unit of measurement of the scale is a Touth of its
distance from the centre of rotation of the sighting tube, then = 1000 and
E 1000 V.
Therefore every millimetre of the amount of the vertical movement V corre-
sponds to one metre of the desired distance E, so that the divided disc g' can be
easily so arranged as to enable the distance to be read off from it directly.
Then according to the above the manner of working will be as follows:-
In position 1 the point B is sighted with the pointer lever in the position m.
Then the telescope is turned so as to bring the pointer lever into the position m-1
The telescope is raised or lowered until the line of sight at this latter inclination
of the telescope again meets the point B, and then the amount of this vertical
movement is read off.
For the purpose of enabling the telescope to be turned to a definite extent, the
hereinafter described arrangements are provided in the instrument shewn viz.
Parallel to the bar that carries the scale at, there is rotatably mounted a screw
spindles which acts upon the pointer lever a. This spindle carries on its free
end facing the observer a hand wheel s¹, the divided periphery of which slides
along a fixed nonius, and extends through a sliding carriage which must
move along the scale bar when the hand wheel is rotated. The sliding carriage s
carries a sliding piece 3 which is capable of being slidden parallel to the scale
by means of a micrometer screws, and has an index a' against which the pointer
lever as is constantly pressed, for which purpose there is employed in the arrange-
ment shown a small rod s which acts upon the back of the pointer a5 and which
is subjected to the influence of a spring situated in the casing s
If now for instance, the vertical distance of the scale from the pivot of the
pointer lever is 200 millimetres, then, with the ratio of division of 1: 1000, the
unit of measurement is equal to 0.2 millimetres. Therefore if the divisions of
the scale are 5 millimetres apart, this distance corresponds to 25 units of measure-
ment. In such case the screw 8 is made preferably with a pitch of 5 in/m, so that
each complete revolution corresponds to the shifting of the index on the scale from
one division to the other; the micrometer screw 8 is made with a pitch of 0.2 m/m,
so that each of its revolutions corresponds to a shifting movement to the extent
of one unit of measurement. Thus if, in the position 1 of the instrument, the
telescope has been directed on to the point B, it is then merely necessary to turn
the micrometer screw s once round, to shift the telescope vertically until the sight
again meets the point B, and then to read off from the disc g' the amount of this
shifting movement. In order that a revolution of the micrometer screw s may
be effected with exactness, it is provided with an index, and may further carry
a spring tooth or the like, which snaps into a recess in a sleeve after each revolu-
tion. In order that it shall not be necessary to read off from the disc g' both
before and after the vertical movement of the telescope, the arrangement is prefer-
ably such that the disc can be set each time at zero, for which purpose it must be
mounted loosely, but so as to be capable of being clamped fast, on the shaft g.
The number of its complete revolutions during the raising or lowering of the
telescope tube is read off from a counting or registering device of usual construc-
tion which is not showi
For the purpose of more convenient manipulation of the instrument, it is advis-
able to arrange the scale at with the entire screw mechanism s to s6, not above, but
below the telescope. The former mode of construction is chosen on account of
the greater ease of illustration.

page_text: .
"
the level of the axis of the turning movements of the telescope.. Conse-
read off in
quently it is merely necessary to multiply the number
-position 1 from the scale, and the handwheel s¹, by the number
read off from the disc g, in order to obtain this difference in height.
On adding this difference to... the... height of the instrument (which
height is to be measured directly), there is obtained the difference in the
levels of the two points a and B. In some cases it may be advisable to sight a
point of given height (for instance when it is desired to determine as hereinafter
described, the width of the trunk of a tree at a known height). In such a case, by
means of the equation H ✓ E, and the known' values H¨and E, the unknown
value m can be determined, and then there is obtained that number upon which
the hand a' of the pointer lever a5 must be set in order that the telescope shall
have the inclination at which the line of sight meets the object at the desired
height. If the quotient of this division is not a whole number or is not such a
number to the fractions of which the hand of the pointer lever can be set by means
of the nonius provided, then the height of the instrument is altered as required
by raising or lowering the telescope.
m
III. DETERMINATION OF WIDTH AND THICKNESS.
As stated at the beginning, the measurement of width can be effected by means
of a vertical thread fixed in the sighting tube, which thread is caused to coincide
first with one and then with the other edge of the observed object. When the
distance of said object is known, and the horizontal turning movement of the tele-
scope is measured, the width is easy to determine. Instead of reading off the
angular measurement of this horizontal turning movement from a divided circle
on the horizontal disc b¹, it is preferable to use a tangent scale similar to the
scale a used for the vertical turning movement. The scale must of course be
horizontal. The pointer lever (which is then also horizontal) for this scale need
not be arranged so as to be constantly turned with the telescope,, but is preferably
clamped fast to a part (turning horizontally with the telescope) only when measure-
ments of widths are to be effected. As this arrangement will be readily understood
without further trouble, from the description of the tangent scale a' for the vertical
turning movements of the sighting tube, the said arrangement is not illustrated.
As will be understood from the preceding description, distances, levels of in-
accessible points, and also the heights and widths of inaccessible objects, can be
determined from the standpoint of the instrument, by. means of said instrument
as described without the necessity of making complicated calculations, so long as
such inaccessible points are visible.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what I
claim is:
is
1. An instrument for measuring distances and heights and for taking levels,
constructed with a telescope which in addition to its rotary motion in a vertical
plane through its longitudinal axis, and a rotary motion in a horizontal sense,
also capable of a variable and measurable vertical movement parallel to itself, the
arrangement being such that the extent of the direct vertical movement, as well 4
as the extent of the vertical turning movement of the axis of the sighting tube
can be read off from the instrument itself for the purpose of determining the
distances, heights and differences of level of observed points, as set forth.
2. An instrument of the construction specified in the preceding claim, wherein
for the purpose of allowing of turning the sighting tube or telescope through a 5
definite amount and reading off the amount of the inclination, there is provided a
screw mechanism s s¹ which moves by means of a sliding carriage s², the pointer
4

page_text: lever as (which turns with the telescope) along a scale a, in combination with a
micrometer screws, by each rotation of which the sliding piece ³ inserted in the
sliding carriages, and consequently the pointer lever a³, is moved a definite
amount, substantially as described.
3. In an instrument of the kind specified in Claim 1, an arrangement for
measuring widths, comprising a horizontal tangent scale of the kind referred to
in Claim 2, along which scale a pointer lever moves which is capable of being
turned in a horizontal sense with the sighting tube, substantially as described.
4. My improved instrument for determining the distance and height of inacces-
sible objects and for measuring the width thereof; constructed arranged and
operating substantially as hereinbefore described with reference to and shown
in the drawings referred to.
Dated this 16th day of March 1898
F. WISE HOWORTH,
46, Lincoln's Inn Fields, London, W.C.,
Agent for the Applicant.