A New and Improved Range and Speed Finder.
Year: 1888

page_text: Date of Application, 1st Aug., 1888
Complete Specification Left, 1st June, 1889-Accepted, 1st Aug., 1889
PROVISIONAL SPECIFICATION.
A New and Improved Range and Speed Finder.
I FRANK CAWs of 60. Fawcett Street Sunderland in the County of Durham
Architect do hereby declare the nature of this invention to be as follows:-
By means of an Eyelet or telescope fitted with cross hairs and swivel jointed, made
in duplicate, or to slide upon a tubo or bar, said tubo or bar being furnished with
cross head fitted with two or more adjustable sights or needle points, I observe from
one station any object moving in the distance across and approximately normal to
the central line of vision; and by micans, of a stop watch or other suitable time meter
I note the exact time when the moving object, proceeding from right to left or vice
versa, as case may be, first comes into line with a needle and the cross hair when the
eyelet, or telescope is in its first position, or (in the case of an instrument having two
eylets or telescopes) with that cross hair which belongs to the eylet or telescope
which is the nearer of the two to the cross head and moving object.
I then, if there be only one eyelet or telescope, slide the same along the bar or
tube to a second position further back from the crosshead than the first position: or,
if the instrument be fitted with two eyelets or telescopes, one eyelet or telescope is
already fixed in the second position ready for use. Then I again observe the moving
object and note the time when it comes into line with the same needle as before and
with the cross hair in the second position. I then turn the eyelet or telescope upon
the swivel joint towards the other needle and note the exact time when the moving
object again comes into line.
When there is only one eyelet or telescope I restore the same to its first position;
or, if there be two eyelets or telescopes, I return my eye to that one which stands in
the fast position; and again observe the moving object, and note the exact time
when it comes into line with the needle last used and with the cross hair.
I have thus obtained four notes of the time in which the moving object traverses
the arc included in the angle between the two needles and the first position of eyelet
or telescope.
Then, by means of a simple algebraic equation, associating the observed times of the
motion over each section of the arc as divided by the angle included between the two
needles and the second position of the eyelet or telescope, by the method of parallax,
I am able at once to learn the distance and speed of the moving object.
In case it be desired to learn the distance of a stationary object, I use, instead of
the needles before named, a horizontal arc of needles fitted to the centre of the
cross head and caused by clockwork or other suitable mechanism to revolve at a
uniform rate.
I observe the exact time in which one or more of these needles traverses the
apparent length of the stationary object as seen from the first position of eyelet or
telescope, & likewise as seen from the second position of same. Then the difference
between the times observed from the two positions as relating to the difference of the
two angles of the arc of observation gives the necessary clue by which the true
distance of the stationary object can at once be ascertained.
Dated this 1st day of August 1888.

page_text: COMPLETE SPECIFICATION.
A New and Improved Range and Speed Finder.
I FRANK CAWs of 60 Fawcett Street Sunderland in the County of Durham,
Architect, do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement:-
The objects of my invention are to enable an observer, with or without changing
the site of his instrument, to measure the distance of stationary objects, and the
distance and speed of moving objects, and also to measure altitudes of distant objects
at rest or in motion.
I attain these objects by means of an instrument which I call my new and
improved Range and Speed Finder, which may be constructed of various types,
and in various materials and ways; but which I preferably construct in greater or
less accordanco-as circumstances and requirements specially dictate-with the
following description, to which I append two sheets of drawing bearing the letters
of reference given in the descriptive text.
The two eyelets, E and E, Fig. 1., are each fitted with cross hairs, and swivel-
jointed so as to turn horizontally in any direction. They are mounted upon the
tube, B, to one end of which the cross tube or cross-head, C, is fitted at right angles
and rigidly fixed by the set screw, S. The cross-head is furnished with one needle
point, or sight, A, standing at intersection of axes of B and O; and also with two
other needle points, or sights, D D, mounted on sliding sleeves, which are adjustable
to any position, between centre and ends of crosshead, by means of the screws, F F.
The sights, D D, are hinged, so as to fold down into recesses of sleeves when not in
use. The crosshead is graduated as indicated, and on each sleeve a vernier, V V, is
engraved, so that D D. can be adjusted to the foot. The tube, B, is mounted
upon a suitable stand or tripod, G, fitted with longitudinal and transverse spirit
levels, HH, and with altitude circle, I, and vernier, J, and altitude clamp screw, K;
also with swivel or ball and socket joint, and compass-not shown-when and as
required.
The instrument, as thus far described, is sufficient for finding ranges altitudes and
speeds of moving objects.
To ascertain distances of fixed objects, the following additional parts of the
instrument are brought into play-riz. The dial-plate, L, which fits upon and is
revolved at uniform rate of motion by the clockwork, T, whose winding key is N,
and whose support is the bayonet catch, P, in a case, or shell, secured beneath tube, B,
a definite distance forward of E¹ as shown on Fig. 1, and also (alternatively) the
same definite distance forward of E, not shown on Fig. 1.
The instrument above described may be used in various modes, together with a stop
watch or chronograph of any suitable kind.
One mode of use may be illustrated by the following example:-Range and Speed
are required, of a ship moving at uniform speed along a distant course normal, or
nearly so, to central line of observation. D D (Fig. 1.) are always adjusted
equidistant from A. The exact distance DA is accurately known, and is the real
measure to which the angular ratios of travel and observed times refer. The ship
proceeds along the coincident bases of two unequal and dissimilar triangles, the lesser
of which lies within the greater, the apex common to both triangles being one of
the points, D. These two triangles (see Fig. 2) seaward of the apex D are similar to
the instrumental triangles, A E D, and A E, D, which also have a common apex
in D. The Observer reads by chronograph the times of ship's travel from her
coming successively into line, first with E, D, next with E D, and lastly with E E, A.
The ratio of times thus observed is the ratio of corresponding distances along the
ship's observed course. This ratio is used as a factor, together with the actually

page_text: observed times and the DA unit of real distance, in a simple algebraic double equation
which at once produces the range and speed required as follows:-That is to say
But the observer, by using Tables of Ranges prepared by the Inventor, is spared
the calculation of the double equation. The only calculation the observer has to per-
form is to divide the lesser observed time-base of the ship's travel by the greater
observed time-base of the ship's travel.
This calculation which is the work of but an instant-gives a product which the
observer will find upon the printed table with the true range next it in the adjoining
column of figures.
There are various methods of finding ranges of stationary objects by means of this
instrument. By one of these methods it is necessary to place one or more needle
points, M M, in the rotating dial plate, L, and to observe, from E and E; eyelets,
the transit of these needle points across the length, height, or any other chosen
dimension of the distant object whose range is sought. The error of observation
which may be due to using only one point (i.e. observing only one transit) is
minimised by repeating the transit observation by using a number of needle points
placed at convenient spaces apart, as the socket holes in dial face allow; so that each
needle in succession may complete its transit before the needle next following
commences its transit. During the observation from E¹ the dial is secured to the
tube B a definite distance in advance of E¹, as shown Fig. 1; and during the obser-
vation from E the dial is secured to the tube B the same definite distance in advance
of E (not shown) Fig. 1. The observer when employing a number of needles, takes,
by chronagraph, the sum of times of M M transits for any given number of transits
(corresponding to the number of needle points employed), first as observed from E₁,
and second as observed from E.
The difference between the sum of observed times from E₁ and from E bears the
same proportion to the sum of times observed from E as the distance between E₁
and E bears to the distance from E₁ to the stationary object whose range is thus
found.
By another method the dial plate remains at the same place on tube B as shown
Fig. 1. during observation both from E' and E. But in this case the results of
observation bear less simple relations to the Range sought, but are even more
effective for range finding purposes.

page_text: Having now particularly described and ascertained the nature of my said Inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is
1. The arrangement of two points of view on one instrument, or apparatus (which
may be of any size) in such a manner as to enable that single instrument, from
one or more sites, to measure distances and altitudes of stationary bodies, and
distances altitudes and speeds of bodies in uniform motion; by means of chrono-
graphically detected differences of visual angles at the two or more points of view,
as generally and particularly described and set forth herein.
2. The arrangement of instrumental sights in uniform motion, by means of whose
chronographically detected differences of rates of transit across the object as observed
from the two or more instrumental points of view-the range of the object is found.
3. The arrangement of the instrument or apparatus as shown by annexed drawing;
or an arrangement of geometrically similar kind; and as generally and particularly
described herein.