A New or Improved Sketching Protractor for Military and other Purposes.
Year: 1886

page_text: Date of Application, 3rd Aug., 1886.
Complete Left, 29th Apr., 1887.
Complete Accepted, 3rd June, 1887,
PROVISIONAL SPECIFICATION.
A New or Improved Sketching Protractor for Military and other
Purposes.
I, HARRY LEITH MACKENZIE, of 14 Victoria Place, in the town and county of
Stirling, Major late Royal Artillery Bengal, do hereby declare the nature of my
invention to be as follows:-
My said Invention has reference to a new or improved and most simple construction
of protractor devised for military purposes to enable the surveyor to accurately
sketch or lay-off on his plan the stations or main points of a piece of country direct
on to the paper, fixing their positions by "intersection," and for "traversing," in filling
in the details of the area under survey; all in a rapid and convenient manner while
riding or passing through it. The instrument would also be most useful in exploring
new country for fixing the relative positions of its mountain ranges or water-sheds
or other prominent features of the country, as well as for other purposes; and would
be especially useful for surveying purposes where the prismatic compass cannot be
employed owing to the presence of iron ore in the ground or iron in the vicinity.
This protractor is so simple and convenient that its vertical sights can be folded down
and the whole safely secured like a short rule or scale in a thin leather or other
protecting case, easily carried in any persons' pocket, or in a cavalry officers sketching
case, or in the sabretache worn by officers on mounted duty, to whose outfit it would
form a valuable auxiliary on field service. And by the use of this protractor the
direction of objects can be laid down on the sketch with accuracy, without using
instruments for observing angles or a protractor for plotting.
That the nature, novelty, and mode of using my improved instrument may be
properly understood, I have hereunto appended a Sheet of Drawings illustrating the
same.
Figures 1, 2, and 3 are respectively a side elevation and a back and front end
elevation of the protractor A, B, C, with the short back sight B, and the tall fore hair
sight C, as set up ready for use on the drawing paper, which is indicated by the
horizontal line P--- P. Figure 4 is a transverse section of the body A of the instru-
ment. Figure 5 is a plan of the protractor corresponding to Figure 1, but showing

page_text: the sights B, C, folded down. Figure 6 is an edge view of the instrument corre-
sponding to Figure 5, also with the sights folded down, but with one of the protecting
plate D removed to show the slide grooves of the sliding steps of the sights B and C,
these grooves and sliding steps being shown as of 1-shape; but they might be of a
dovetail shape when preferred. The two bevelled edges a and 6 of the central body
part of the instrument are divided into yards on scales of 6 inches and 4 inches to the
mile, respectively, which satisfies the ordinary purposes of the military sketcher. On
the under surface of the body A, as shown in Figure 7, are given diagonal scales of
inches, half-inches, and of chains and links at d, also a scale of horizontal equivalents
at
e, for contouring in hill sketching, for vertical intervals of 10 feet at 12 inches to
one mile.
This latter will serve for contouring as well at other scales that will divide
it, as 3", 4", 6", to one mile, remembering to make the necessary changes for the
vertical intervals and horizontal distances in thus applying it. The diagonal scales d
of inches will enable other plan scales to be constructed. In using the instrument,
the sights B, C, are slid laterally in the guide recesses B¹, C₁, in the end parts A¹ of
the instrument to either side, according to the scale intended to be used, until they
come up against the end stop plates D enclosing the recesses; in either of which
positions the centre of the back sight, the ruling edge of the scales a, b, and the hair
in the fore sight, are placed in the same alignment, thus forming a sighted ruler. In
sighting an object, the arrowhead at the end B, (at the angle formed by the narrow
portion A, of the ruling edge with the broader end), is placed directly over the station
on the sketch, or in which, (for convenience in observing the directions of several
objects from the same point), may be fixed a needle, on which to pivot the protractor;
the sights B and C are then aligned on the required object, or objects, by looking
through them, so as to get the centre of the back sight, the hair of the front sight and
the required object in the same alignment; a line is now drawn with pencil on the
sketch along the edge of the ruler a or 6 to indicate the necessary direction. Each
object in succession is taken in the same way and the lines of direction drawn thereto
on the sketch, writing the names on the several directing lines. Similarly, after
"setting" the sketch at the new station by adjusting it to correspond with the country,
the surveyor completes his intersections from the new point and fixes the positions
of the objects previously observed. The distances, as measured, are marked off from
the scales, and the surveyor works on in this way filling in the positions of details by
intersection, without the use of the protractor.
The sights B, C, being hinged and secured to the instrument by the end plates D
are not liable to be lost; and if required to be renewed or replaced, this can easily be
done by removing a plate (D) from either end of the grooves in which they slide, and
refixing the plates.
The body part A of the protractor would preferably be made of well seasoned box-
wood or ivory; and the sights and their sliding hinged steps, as well as the plates at
the ends of the grooves, may be made of nickel-silver or brass, or of steel case-hardened
and blued. A fine hair or aluminium or other wire may be used for the central hair
of fore sight.
1
n
004

page_text: COMPLETE SPECIFICATION.
A New or Improved Sketching Protractor for Military and other
Purposes.
I, HARRY LEITH MACKENZIE, of 14 Victoria Place, in the town and county of
Stirling, Major late Royal Artillery, Bengal, do hereby declare the nature of my
invention and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement in writing, reference being had to
the accompanying sheet of Drawings, and to the letters and figures marked thereon,
that is to say :-
My said Invention has reference to a new or improved and most simple construction
of protractor devised for military purposes to enable the surveyor to accurately sketch
or lay-off on his plan the stations or main points of a piece of country direct on to the
paper, fixing their positions by "intersection," and for "traversing" in filling in
the details of the area under survey; all in a rapid and convenient manner while
riding or passing through the country. The instrument is also most useful in exploring
new country for fixing the relative positions of its mountain ranges or water-sheds
or other prominent features of the country, as well as for other purposes; and is
especially useful for surveying purposes where the prismatic compass cannot be
employed owing to the presence of iron ore in the ground or iron in the vicinity.
This protractor is so simple and convenient that its vertical sights and graduated arc
can be folded down and the whole safely secured like a short rule or scale in a thin
leather or other protecting case, easily carried in any persons pocket, or in a cavalry
officers sketching case, or in the holsters on the saddle, or in the "sabre-tache worn
by officers on mounted duty, to whose outfit it would form a valuable auxiliary on
field service. And by the use of this protractor the direction of objects can be laid
down on the sketch with accuracy, without using instruments for observing angles or
a protractor for plotting.
دو
And in order that the nature, novelty, and mode of using my improved instrument
may be properly understood, I have hereunto appended a sheet of Drawings illustrating
the same, in which the same reference letters are used to indicate corresponding parts
in all the Figures where shown. Figures 1, and 3 are respectively a side elevation,
and a back and front end elevation of the protractor A, B, C, with the short back
sight B, and the tall fore hair sight C, as set up ready for use on the drawing paper,
which is indicated by the horizontal line P---P. Figure 4 is a transverse section of
the body A, of the instrument as taken on the line 1--- 1 of Figure 1 looking forward,
showing the new level E and clinometrical arc F. Figure 5 is a plan of the protractor
corresponding to Figure 1, but showing the sights B, C, folded down and the
graduated clinometrical arc F shown vertical, but dotted in as folded down and
swivelled under the level E. Figure 6 is an edge view of the instrument corre-
sponding to Figure 5, with both the sights B, C, and the clinometrical arc F folded
down, the latter under the level E. Figure 7 is an under or inverted side view of
the protractor, utilised for certain useful scales as hereinafter described.

page_text: Referring to these drawings:-The two bevelled edges a and b on the upper side of
the central body part or bar A of the instrument are divided into proportional
divisions of yards on scales of six inches and four inches to the mile, respectively,
which satisfies the ordinary purposes of the military sketcher. The upper side of one
edge of the instrument, and the two ends are bevelled down to a fine edge at A¹, and
marked off in degrees as an ordinary protractor to set off any angle on the paper
from the centre and opposite edge a, a, of the protractor. By means of this same
scale the resulting measurement in degrees of the angle contained between two lines
can be readily ascertained, by placing the arrow, in the centre of the edge a a, at their
point of intersection, and observing where these lines (or the lines themselves
produced if necessary) issue along the opposite edge A', A¹ as radii from that central
point.
On the under surface of the body A, as shown in Figure 7, are given a diagonal
scale of inches, half-inches, and of chains and links at d; also a scale of horizontal
equivalents at e, on the outer bar A¹ of the body of the instrument, for contouring in
hill sketching, for vertical intervals of ten feet, at twelve inches to one mile. This
latter will serve for contouring as well at other scales that are factors or multiples,
as 3" and 6", or 24", to one mile, remembering to make the necessary changes for
the vertical intervals and horizontal distances in thus applying it. The diagonal
scales d of inches will enable other plan scales to be constructed.
In using the instrument, the sights B, C, are preferably by fixed stop hinges at B¹
and C made to fold up vertically in the centre line of the instrument, parallel to the
edge of the scales a and b; that is, having the central slit in the back sight B, and the
hair in the fore sight C, placed in the same parallel vertical alignment with the ruling
edges a, b, thus forming a sighted ruler along either scale edge required. But the
hinges B, C, might be made to slide laterally in guide recesses formed in the upper
face of the end parts A' of the body A of the instrument to either side in line with
the edge of the scale a or b intended to be used, when they came up against the ends
of the recesses, although this is not preferred. In sighting an object, the arrow
head at the end B, (at the angle formed by the narrow portions A. of the ruling edge
with the broader end where the divisions begin on the two scales a, b) is placed directly
over the station on the sketch, or in which, (for convenience in observing the
directions of several objects from the same point), may be fixed a needle, to pivot the
protractor on; the sights B and C are then aligned on the required object, or objects,
by looking through them, so as to get the slit centre of the back sight B, the hair of
the front sight C, and the required object in the same alignment; a line is now drawn
with pencil on the sketch along the edge of the ruler a or b, to indicate the necessary
direction. Each object in succession is taken in the same way and the lines of
direction drawn thereto on the sketch, writing the names on the several directing lines.
Similarly, after "setting" the sketch at the new station by adjusting it to correspond
with the country, the surveyor completes his intersections from the new point and
fixes the positions of the objects previously observed.
The distances, as measured, are marked off from the scales, and the surveyor works
on in this way filling in the positions of details by intersection, without the use of the
protractor. The instrument is now also fitted with a spirit level E in the clear space
between the two sights B and C, and secured to a sight bar E', hinged to a fixed
stud E at its back end, and fitted with a socket E³ at the other, oscillating on a
graduated clinometrical arc F divided off to 60° or 70° or so, so that the protractor A
may be set level at the station, and then raised on the arc F in line with the distant
objects, to read off the angles on the arc of elevation of these distant objects by
looking along sights parallel to the oscillating centre of the level, or to the protractor
on the sights A and B when taking depressions, or angles below the level of the
station. In order to obtain angles of elevation, the instrument must be inverted,
namely, the flat surface will be uppermost, with the arc and spirit level down to read
off the angles required on the arc.
The glass of the spirit level E is covered in by a thin curved hinged plate D to
protect it from breakage when not in use. The inner surface of the hinged plate D

page_text: is highly silvered or polished, to reflect the bubble of the spirit level E, and admits of
seeing that the bubble is correctly centered when observing elevations or depressions.
The clinometer arc F is so mounted by a swivelling pin to the centre bar A of the
protractor and a horizontal folding hinge at f¹ above this, that it can be folded down
flush with the upper surface of the bar A, and swivelled in below the level E, as
indicated in Figure 6, and in dotted lines in Figure 5. This swivelling pin of is
indicated in the section Figure 4 A, secured by two small plates and screws to
the upper surface of the bar A, and the level is secured by a small hook catch e.
Although not shown in the Drawings, the clinometrical arc F may have teeth cut
either on the inner or outer segmental edge, and have a small pinion working in it
with a short spindle and milled head, carried in the socket end of the sight bar E¹ of
the level E; and a small screw may also be fitted for fixing the bar to the part of
the arc where set.
The body part A A¹ of the protractor is preferably made of well seasoned boxwood
or ivory; and the sights B and (and their hinged steps B'C' as well as the case of
the level E, and its fittings and the graduated arc F, may be made of nickel-silver
or brass or of case-hardened steel or other metal which would stand the action of the
weather. A fine hair or aluminium or other wire may be used for the central hair of
fore sight C.
For plane table work, this instrument will be especially useful, in adjusting the
level of the sketching board, and similarly in "sketching without instruments,"
sometimes termed " eye sketching" for military purposes.
Having now particularly described and ascertained the nature of my said invention,
and in what manner the same is to be performed, I declare that what I claim is,-
First. The general construction, or arrangement and combination of the parts of a
portable sketching protractor with its scales and folding-down parts for military and
other purposes, substantially as herein described in reference to and shown in the
accompanying drawings.
Second. In a sketching portable protractor A, A', the arrangement of back and
fore sights B, C, ranged parallel to the rule division edges a, b, either with or without
a level E and clinometrical graduated arc F, substantially as and for the purposes
herein described in reference to and shown in the accompanying drawings.
Dated this 90th do of Anvil 1887