AN IMPROVED METHOD OF AND APPARATUS FOR MEASURING DISTANCES, APPLICABLE FOR FINDING THE RANGE OF ARTILLERY, COAST SURVEYING, AND FOR OTHER LIKE PURPOSES
Year: 1877

page_text: LETTERS PATENT to Pringle O'Hanlon Barnes Wollen, of 46, St. Paul's
Road, N.W., in the County of Middlesex, for the Invention of "AN IMPROVED
METHOD OF AND APPARATUS FOR MEASURING DISTANCES, APPLICABLE FOR
FINDING THE RANGE OF ARTILLERY, COAST SURVEYING, AND FOR OTHER LIKE
PURPOSES." A communication from abroad by Arwed Hahn and Richard
Hahn, both of Cassel, in the Empire of Germany, Manufacturers,
PROVISIONAL SPECIFICATION left by the said Pringle O'Hanlon Barnes
Wollen at the Office of the Commissioners of Patents on the 18th May 1877.
PRINGLE O'HANLON BARNES WOLLEN, of 46, St. Paul's Road, N.W., in the
County of Middlesex. "AN IMPROVED METHOD OF AND APPARATUS FOR MEA-
SURING DISTANCES, APPLICABLE FOR FINDING THE RANGE OF ARTILLERY, COAST
SURVEYING, AND FOR OTHER LIKE PURPOSES." [A communication from abroad by
Arwed Hahn and Richard Hahn,--both of Cassel, in the Empire of Germany,
Manufacturers.]
This Invention relates to a novel method of finding the range of artillery, and
ascertaining or measuring distances, in surveying coasts, and other surveying and
levelling work, and comprises novel apparatus or instruments for carrying the samė
into effect.
Other methods and apparatus heretofore used for finding the range of artillery
have been found very inefficient, as they only give or permit an estimate of the
direct distance from the apparatus to the object; but by this Invention the
vertical interval or distance of the object from the base of observation is accurately
determined.
I will more particularly describe my improved apparatus with reference to its
use as an artillery range finder. The said apparatus consists of two instruments,
herein-after referred to as No. 1 and No. 2. Each of these instruments comprises
two principal portions, namely,―
1st. The stand, provided with means for horizontal and vertical adjustment.
And, 2nd. A frame, with telescopes, tangent scale, and other fittings.
The said stand has a three legged wooden rest, and the appliance for the hori-
zontal adjustment or revolution is fastened to a plate at the top of the tripod by

page_text: means of a screw rod and spiral spring. And there is a micrometer arm at its
upper part for fixing the said horizontal appliance or "movement."
In the said tripod is a tightly fitting double conical steel axis attached to a
three lobed plato, whercon the aforesaid frame is fixed by means of screw nuts when
in use.
By means of the clamping device of the micrometer arm the revolution of the
steel axis is arrested, and the same may be controlled by means of the micrometer
scrow.
The vertical adjustment for sighting is assisted by three regulating screws whose
lower ends rest and work in metal sockets, and which are provided with circular
milled heads for convenience of manipulation.
For the protection of the said apparatus during its transport or removal the said
stand is furnished with a cap provided with a bayonet lock or fastening, and when
the aforesaid three legs are closed or flapped" and strapped together the entiro
apparatus can be conveniently carried like a fire-arin.
[[
The aforesaid frame has mounted on it the observation telescope, to which is
attached a tangent scale, a vernier, and other devices for micrometer work; also a
rule, to which are attached a telescope stand and vision telescope.
Also an astronomical telescope with "Huyghen's" ocular cross hair and linear
magnifying power and tangent scale.
In each instrument the rule point is on the left side. Decrease is marked to the
left and increase to the right of the millimeter scale on which the vernier is applied.
The vernier and the holder can be readily shifted on the observation telescope;
the holder is fastened by a screw; this part is split and furnished with a nut.
When the holder has been screwed into its place the vernier can be fixed by the
micrometer screw.
The aforesaid rule is formed of a cylindrical brass rod, and has at its upper end
a small axis which fits into a box screwed upon the frame; this arrangement
permits the revolution of the said rule in the plane of the frame. Inside the said
rule are soldered and screwed two iron pieces, in which works without "windage"
a polished cylindrical steel rod with a flat end. This end is united to the vernier
by a small screw axis.
By displacing the vernier the steel axis is caused to shift in its two rests, and as
the said vernier always remains parallel to the tangent scale it causes either a
lengthening or shortening of the said rule. To the flat front extremity of the said
steel rod is secured a second vernier, for indicating distances on the line of sight.
To the said rule is secured the supporting piece for the aforesaid vision telescope.
The said telescope can be dipped or inclined vertically thereon about 10 degrees,
and has a strong orthoscopical, ocular, linear magnifying power, and cross hair with
parallel threads.
For the further support of these parts I provide a friction bar and rollers; the
latter run in a circular part of the frame and thus prevent any lateral deviation in
the vertical movement of the telescope.
During the transport or carriage of this apparatus each frame, with the parts
connected therewith, must be packed in a wooden case, which may be carried on
the shoulder by the aid of a strap. Two leads, always kept in this case, serve to
keep the pivots or turning points of the observation instruments accurately over
the extremities of the measured base.
The said Invention further comprises the following improvements, namely:-
The cylindrical observation telescopes are formed at the same time to serve as
the tangent measure; the optical axis of the observation telescope is thus simply
and securely arranged parallel with the tangent scale. On the tangent measures are
movable verniers, the division parts of which remain even in the most extreme
position parallel with the aforesaid tangent mechanism.
The aforesaid rule is also provided with a vernier, which shows in any position
of the rule how much it has been elongated or extended from its normal position.
The calculation is marked on a division list, which is also represented graphically

page_text: to ensure great and sufficient exactitude of calculation in each special case and with
any base.
In using this improved apparatus the base line, at whose extremities the said
instruments must be placed, is found by the ordinary steel tape or otherwise.
When the instruments Nos. 1 and 2 have been placed they are sighted by means
of the observation telescope; then by means of the vision telescope the "object" of
cach instrument is brought between the parallel threads of the cross bar, and the
tangent lengths read off on the vernier. The measurements of each instrument
are communicated to the operator of the other instrument, and by comparison and
simple calculations the distance to be measured may be accurately ascertained.
This instrument is available for any given base from 20 to 200 metres in length,
and at the same time, when once a position has been selected, fixes all objects aimed
at within a visual angle of 56 to the rear or front of the apparatus.
The said instrument acts more accurately than any other known apparatus used
for like purposes. In accurate working it even surpasses the theodolite, and is thus
readily applicable for the survey of ground and especially for military purposes.
The aforesaid apparatus or range finder is also applicable for other scientific
purposes, for instance, for measuring angles.
It may also be made to serve as a levelling instrument by placing suitable devices
upon the observation telescope and by using a distance lath.
It may also be made serviceable as a theodolite by putting a height circle with
vernier on the rule or on its telescope.
Instead of the height circle I may employ a vertical tangent measure with a
shifting vernier.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Pringle O'Hanlon Barnes Wollen in the Great Seal Patent Office on
the 17th November 1877.
"
PRINGLE O'HANLON BARNES WOLLEN, of 46, St. Paul's Road, N.W., in the
County of Middlesex. AN IMPROVED METHOD OF AND APPARATUS FOR MEA-
SURING DISTANCES, APPLICABLE FOR FINDING THE RANGE OF ARTILLERY, COAST
SURVEYING, AND FOR OTHER LIKE PURPOSES." A communication from abroad by
Arwed Halin and Richard Hahn, both of Cassel, in the Empire of Germany,
Manufacturers.
This Invention relates to a novel method of finding the range of artillery, and
ascertaining or measuring distances, in surveying coasts, and other surveying and
levelling work, and comprises novel apparatus or instruments for carrying the
same into effect.
Other methods and apparatus heretofore used for finding the range of artillery
have been found very inefficient, as they only give or permit an estimate of the
direct distance from the apparatus to the object; but by this Invention the vertical
interval or distance of the object from the base of observation is accurately
determined.

page_text: I will more particularly describe my improved apparatus with reference to its use
as an artillery range finder.
Figure 1 is a plan or top view of an instrument constructed according to this
Invention. Figure 2 is a front elevation, and Figure 3 is a side elevation of the
same.
Figures 4, 5, 6, 7, 8 show portions of the said instrument detached.
Like letters indicate the same parts throughout the Drawings.
The said apparatus consists chiefly of two instruments, herein-after designated
No. 1 and No. 2. Each of these instruments comprises two principal portions,
namely, the stand A, with appliances for moving it on a horizontal arc and for
accurate adjustment of sight, also for vertical movement; and the frame B, provided
with telescopes, tangent scales, and other devices.
The said stand A is divided into a three-legged wooden rest and a horizontal arc,
which is fastened to the top plate of the tripod by a screw rod and spiral spring,
and includes the tripod and the micrometer arm Cat the upper part for adjusting
the horizontal sighting. In the said tripod is a double conical steel axis, which fits
in quite tightly, and is fastened to the three-lobed plate a, a, upon which the frame
B, B, is secured with screw nuts when in usc. On screwing up the knob of the
micrometer arm, the revolution of the steel axis is checked, and it can be accurately
adjusted by means of the micrometer screw h.
The accurate vertical adjustment of the instrument is obtained by turning the
three regulating screws w, which are formed with rounded heads that rest in brass
sockets, and are furnished near their lower ends with small wheels for convenience
of handling.
To protect from injury the appliances for adjusting the instrument horizontally
and otherwise, the said stand is supplied for purposes of transport with a tin cap,
which is locked "bayonet fashion," and when the three legs are folded together and
strapped, the whole can be conveniently carried away.
The frame B is preferably formed of wrought iron, and comprises,
1. The cylindrical observation telescope M, to which is attached a tangent scale,
the vernier N, with its support S, and the micrometer work.
2. The rule C, to which is attached the telescope stand T, and the vision tele-
scope V.
1. The astronomical observation telescope is provided with Huyghen's ocular and
simple cross hair and linear magnifying power of 20; it serves also as a tangent
scale, being divided on the front into millimetres. In each instrument the null
point is on the left, outside, so that if the optical axis of the vision telescope V stands
at right angles to the optical axis of the observation telescope, the vernier or nonius
point is at the number 250 of the millimetres' scale, on which decrease is marked to
the left and increase to the right. Thus the vernier is only a single one and
marks
=0.05 m/m direct, and allows a calculation of 0 = 0.025 m/m The
vernier N and its support S can therefore be casily shifted on the cylindrical obser-
vation telescope. The support S is fastened by the screw K, and furnished with a
female screw for the screw K to work in. When the support S has been screwed
in, the vernier can be adjusted by the micrometer screw.
2. The rule C' consists of a cylindrical brass rod, and has at the upper end the
small projection a, which fits into the socket b.(this socket being screwed on the
frame), and thus permits the movement of the rule in the horizontal plane of the
said frame. Inside the said rule are soldered and screwed in the two wrought-iron
projections x, x, in which works the steel rod 8, which is turned cylindrical and
polished. Its flat end is joined to the vernier N, and revolves round the small
screw axis q.
By moving the said vernier the steel rod is caused to slide to and fro in its two
rests, and as the vernier or nonius point always remains parallel to the tangent
scale, it causes either a lengthening or shortening of the rule. If the nouius point
stands at 250 /m of the tangent scale perpendicular to the observation telescope,'

page_text: then the distance from the axis a to the axis q is 250 m/m At the flat front end of
the steel rod is fastened a second vernier N¹, which indicates directly how much per
thousand the distance of the object measured along the line of sight is longer than
the measured distance of the object from the base. To the rule is screwed the small
stand T, which supports the astronomical vision telescope V. This telescope can be
elevated or depressed about 10°, and has an orthoscopical, ocular, and linear magni-
fying power of twenty-five (25) times, and a cross hair with parallel threads. For
the further support of the stand there is attached to the said rule the friction part R,
the two rollers of which run on the circular arc O of the frame, and thus prevent
any droop in the vertical movement of the telescope. For convenience of transport
each frame, with its appurtenances, is placed in a wooden case which is carried over
the shoulder by a strap. Two leads are provided, which in this case servo to keep
the axis of the observation telescopes exactly over the extremities of the measured
base.
In using the aforesaid instruments, the base, at the extremity of which the
instruments will be placed, must first have either been measured direct with a steel
band or tape, or ascertained by one of the instruments by crecting a short additional
base by means of a lath or rod with two signal dials.
For a distance of 5,000m, relatively 10,000m, a base of 50,100 metres sufficies.
This need not lie in a horizontal plane, and it is immaterial if one of the instruments
should be placed on higher ground than the other.
When the said instruments have been properly placed "they sight" each other
by means of the observation telescopes, the inovable screws of the tripod being
adjusted till the cross hairs of each observation telescope exactly, and in every
direction, coincide with each other.
To make the sighting more accurate a large white tin dial may be placed on each
object-glass of the observation telescopes. Then by means of the vision telescopes
the object whose distance is to be ascertained is accurately brought between the
parallel threads of the cross hairs of both instruments, and the tangent lengths read
off on the verniers.
In order that the operator at each instrument may at once learn the reading of
the other, this reading is marked with chalk on a small slate to be hung on each
observation telescope. If the two instruments are not further from each other than
50m the measurements can be called verbally to the officer standing in the middle
between the operators in charge of each instrument. Then, and by comparing each
statement with the base, the distance can be at once ascertained by means of the
graphical division list or by the graphic factor list.
If B = length of the base in m
1711
1711-
In the rare cases, when the base has to be found by means of the instruments
themselves in consequence of the ground between them being unapproachable, then
a short second base of 10 or 20m is to be staked out under one instrument, if
possible, perpendicular to the tangent measuring scale, and consequently in the line
of vision telescope stationed at 250mm, or to be marked off by means of the aforesaid
lath (which should be 3m in length, and made to fold up) and the signal dials.
In the normal position of the neighboring instrument the apparent magnitude
of the second base can be discovered by sighting the respective extremities. Thus
we obtain, for instance, a second base of 10m by an apparent magnitude = 38 425mm
base
250.10
38.425
=
65.03, which calculation can also be immediately read off from the
graphic division list, or off the factor list in which the measured tangents m
== mi

page_text: aro indicated exactly as ordinaries up to
The length of the base can be read
m = 10mm.
-
mm, that is to say, for 1 11mm.
off accurately from 30 to 80m up to
The use of the division list to determine D from a given base, and measured
ՊՆ m, is so simple that no farther explanation is here considered necessary.
But it must be borne in mind that in case of a lengthened stay at any one base it
is advisable to make the ordinaries of the base thus made use of in the graphic
division list more apparent by a lead line.
For the interpolation between two degrees of values which differ as to the
magnitude of D by 100m,, a card can be introduced, the same being divided at the
edges into equal parts, as shewn in Figures 9 and 10.
In case the distances of the objects measured along the line of sight have to be
ascertained in addition to the distance D, then the second vernier at once indicates
how much per thousand the former is longer than the latter; or a small auxiliary
list is introduced in which is stated how large m¹ or m! must be to allow L or L¹¹
to be 1, 2, 3.50 per thousand longer than the appertaining D.
-
When the base has been carefully measured it will be advisable to make use of a
list from which can be read off at once D for m¹ m. Such a list is for the base
lengths. 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, and 100m, as also
for D = 600 to 6500, D thus increasing for every 100m calculated.
=
-
m11
The figures on the above card will indicate the decrease or increase of m
in proportion to D by every 100m, and thus serve to explain how D can be quickly
and accurately ascertained."
-
. As soon as by the opening fire of a battery against any stationary object D has
been ascertained from the measured m₁ m, and by observing the smoke of a
bursting shell it will only be necessary to determine the difference (m,
M₁) in order to at once discover the error, that is to say, how much too far
beyond or too short of the object the trial shot has burst; for instance, let the
(M
-
.Base= 60, ՊՆ ՊՆ,
therefore D = 2251m.
-
m11)
-
mii
= 6.665mm,
Trial shot 1 gives y₁
-
mii
-
6.950mm,
therefore error
6.9506.665
0.300
1
Trial shot 2 gives y₁
-
100 =
285
m6.250mm,
=93m too short.
ن
therefore error
6.665 - 6250
100 ===
0.270
I
4150
27
= 153m too far.
Each individual operator must make use of either a division list or factor list, or
graphic division list, or graphic factor list, prepared for use with these instruments,
that is to say, these two or rather four methods of calculation help to elucidate the
knowledge of the theory and the practice of the present range finder, and present
the method of calculation preferable to each separate person, and at same time
produce material for the critical examination of other competing instruments for
measuring distances.. -
All existing range finders have been very limited in their practical value, because,
in consequence of estimating instead of actually measuring the angles between the
extremities of the base and their objects, it became necessary in order to obtain
even approximate results, to take a base of 400m up to 1700m, and even then the
result has been about the quadruple of the base with errors of 3 to 4 per cent.
The range finder above described surpasses all others for accuracy, and works
with a base of 50m to 100m, up to distances of 10,000m with the highest medium
error of 0.5 (per cent.) respectively 0-2 (per cent.).
To simplify the result, and to avoid trigonometrical calculation use is made of the
tangent scale, which has never heretofore been exhibited in this style on any
instrument. The present Invention therefore illustrates the fact that the height
of a triangle can be found when the base of the triangle is given, and the tangents

page_text: B
D =
1
250
111 +1
-
250 1
'
The result remains the same if x or y change the sign as shown in the last-
named Figures of the Drawing. But as the tangents m, and m₁ have different
readings, if they incline from the left to the right, or vice versa, the null point of the
tangent scale is fixed at 250mm, inclining from the centre to the left, so that tangents
have always to be measured to one side, that is to the left. Hence for all cases the
normal equalization has to be changed to D
by which means are obtained
the great advantages of requiring only one vernier or nonius with null point to the
left and the avoidance of all errors that might occur with double verniers. Moro-
over the distance of the object is not measured from either end of the base, a
custom prevailent in trigonomictrical surveying, and made use of also for range.
finders, but I first ascertain the height of the triangle between the object and base,.
that is to say, for all objects within a visual angle of 90 degrees. It is therefore.
possible to determine either in metres, yards, or any other measure, the D angle for
the base for all objects, either far or near, or to the left or right, for about 30° of
the closed base without moving or changing position of the instruments.
The distances of the object measured along the line of sight of both instruments
are functions of D and m₁, or m₁, which the second vernier in the rule immediately.
indicates in metres.
In practice it will be sufficient to seek from the accompanying base list (which
indicates how much L, or L₁, is greater than D) with a fixed measured m, or m
an increase per thousand for D to ascertain L, or L. Although the theory of this
range finder is based on purely geometrical principles and rules, this method of
measuring has never been practised for purposes of field and fortress warfare, or for
a rapid survey of ground. The value of such an efficient range finder will be much
enhanced if it can be made use of to control and discover how much too far or too
near a shell has burst from the object aimed at.
The faults of optical error which so often have caused waste of ammunition in
firing from long ranges, such as 2500, 3000, 4000m, against objects on broken ground,
will thus be prevented.
As an instance of the advantage of a range finder, which measures the declination
of the firing point from the object, I will take the following example, referring for.
its illustration to Figure 14 of the Drawings:-In ignorance of the distance, orders
are given to the commander of battery A to fire on the enemy's battery stationed.
at B. The ground is undulating and thickly covered with shrubs, hedges, and
other obstructions, especially in the neighborhood of the enemy's position. Battery
A opens fire on the fork (Gabel) system with sights raised for 3000m; then 3400m,
3200m, 3300, 3100m. At 3000 and 3100, the effects of the fire are observed, but
cannot be seen at the longer distances. It is therefore presumed in battery A that the
object has been already overshot at 3200m, and that the sights at 3100 produce the
best results upon the objects aimed at, which however is 3000m distant, and con--
sequently is not struck by even a spent fragment of a projectile. Firing under
such difficult circumstances leads not only to waste of ammunition, but to the.
certain sacrifice of infantry to be advanced against the eneiny's artillery, which is

page_text: still intact, but has probably been much injured by the preceding fire of battery A.
If the above described improved range finder be at the disposal of the A battery,
quite different orders will be given for engaging the B battery, that is to say, A opens
fire at a distance of 3900m, measured by the instruments, and bas a chance of
hitting with the first trial shots, even allowing for a scatteting of 180m.
If the shots fall short and disappear in the valley, which in the present case is
800 to 900 wide, and lies just before the B battery, without being visible from A,
then it is necessary to cease firing to see where the shells burst at 3100 or 3000m, and
measure their distance from the object fired at. It will be easily seen what orders
are necessary to indicate that the shots are falling short of or beyond the object
fired at or when their effect is not visible.
In garrison and seige warfare firing at concealed objects is more general than in
the field. Aim has to be taken at the smoke or flash of the enemy's guns, and their
distance has to be measured as sole means of guideance for the necessary elevation,
because in many cases the exact point at which the shells burst cannot be seen.
To discover the daily clevation of the guns for this distance, trial shots must be
fired at some open ground lying to one side, about 10 to 20 degrees, then the distance
of these shots must be ascertained by the present range-finder and the elevation
corrected. When the real daily elevation has thus been discovered the fire must be
directed on the concealed battery of the enemy with an increased probability of
hitting, even if it be not possible to observe the hitting or bursting of the projectiles
because of the unevenness of the ground.
The utility of this improved apparatus will be much increased in fortresses and
on the coast by the laying down on the ground of flagstones to form stations, with
3 steps for the legs of the stand of the instruments, and by cutting the lengths of
the different bases into these stationary flagstones.
For ships of war and other vessels it will be advisable to indicate on the ship's
.sides four stations for the instruments, as shewn in Figure 15 of the Drawings.
The base length of a cor bd is about 75 to 80m, and the same from a dor be
would suffice for all distances; and even positions from ab or dc of only 8 to 10m
would be practicable for objects up to a distance of 3000m.
For scientific voyages it would be easy to survey the whole coast of any district
from the vessel rapidly and correctly by means of these instruments by fixing the
distance of any prominent object. With these instruments it would be possible to
effect very rapidly, and with at least as much accuracy as with a theodolite, a survey
of ground covering two to three square miles by using the apparatus shewn in
Figures 16 and 16. Figure 16 is a side view; Figure 16a is an end view drawn to
an enlarged scale. I place upon the observation telescopes and the tangent scales
a spirit or air level, with a semi-cylindrical base, to render the instrument available
for levelling purposes.
For the erection of rauge finders to measure distances of all objects within a
visual angle of 360 degrees comfortably, rapidly, and correctly in prepared positions
or stations in fortresses and on board of ships, I use a right angular station triangle
with 30, 40, or 50m side lengths, or a combination thereof, as illustrated in Figure 17
of the Drawings.
To be able to determine for all objects within a circumference of 360 degrees the
perpendicular intervals (or D) of several adjoining lines, marked and serving as a
base, the sides of a triangle will suffice. Thus,-
A, C.
= 30 or 45 or 60m
A, B. = 50
C, B.
"
75. ⟫
= 40
60
23
رو
100m
80m
It is consequently advisable to select the longer triangle side C,B., as the most
suitable for observation. In practice however, many objects are marked by pro-
jections. In such a case it is advisable to mark off two triangles, united to form a
square, thus employing as a base not only the four sides, but also, if deemed neces-
sary, the two diagonals.

page_text: points A, B, C, D, large flagstones of 60 to 80mm in thickness, and of a length
of 700mm, are to be laid on the ground in such a manner that their centres
represent the corner points of the measured triangle sides. From the centre of each
flagstone a circle is to be formed of 250mm, as shewn in Figure 18, and in certain parts
of this circle, if possible at equal intervals, and hence in an equilateral triangle,
cuttings or incisions should be made for the 3 feet (steps) of the instrument stands.
The direction and distance of the next "station" points should also be cut into these
flagstones.
When these station flagstones have thus been placed permanently on the fronts
of the fortress the range finder can be placed without loss of time on the carefully
determined base lengths and the measurements taken.
Figure 19 of the Drawings illustrates an equilateral station triangle, with side
lengths of 40 or 60 or 80m, and the like. The object O¹ can only be measured
from the position A, C, but object O", and all similarly placed objects, from several
points. This position upon 3 points of an equilateral triangle is specially advisable
for survey of ground, and also in and near advanced forts. One covers, if A, C, be
the principal front position, be the side or flank position, 300° if B be in the
rear, or 180° if B be in front.
Figure 20 of the Drawings illustrates an equicrural station triangle of 40, 40, 50m,
or 60, 60, 75m, or 80, 80, 100m. With a position of A, C, as principal base,
as an auxiliary base; one covers a visual angle of rather
Jess than 180° if B be in front,
more 180°, B be in the rear.
"3
Having thus fully described the said Invention as communicated to me by my
foreign correspondent, and explained the manner of carrying the same into practice
in the various examples illustrated in the accompanying Drawing, I wish it under-
stood that I claim, for carrying into effect the above described novel method of
measuring distances, for obtaining the range of artillery, for surveying, and other
like purposes, the improved apparatus or instruments consisting of the aforesaid
peculiar parts and devices, by whose construction, combination, and adjustment the
desired results are obtainable in the manner above set forth.
In witness whereof, I, the said Pringle O'Hanlon Barnes Wollen, have hereunto
set my hand and seal, this Sixteenth day of November, in the year of
our Lord One thousand eight hundred and seventy-seven.
P. WOLLEN. (L.S.)