AN IMPROVED INSTRUMENT TO DETERMINE ANGLES OF ALTITUDE OR ELEVATION WITHOUT THE NECESSITY OF A VIEW OF THE HORIZON BEING OBTAINED
Year: 1825

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, the Reverend
WILLIAM BARCLAY, of Auldeare, in the County of Nairn, send greeting.
WHEREAS His present most Excellent Majesty King George the Fourth,
by His Letters Patent under the Great Seal of Great Britain, bearing date
at Westminster, the Thirtieth day of July, in the sixth year of His reign, did,
for Himself, His heirs and successors, give and grant unto me, the said
William Barclay, His especial licence that I, the said William Barclay, my
exors, adñiors, and assigns, or such others as I, the said William Barclay, my
exors, adiñors, and assigns, should at any time agree with, and no others,
from time to time and at all times during the term of years therein
expressed, should and lawfully might make, use, exercise, and vend, within
England, Wales, and the Town of Berwick-upon-Tweed, my Invention of
"AN IMPROVED INSTRUMENT TO DETERMINE ANGLES OF ALTITUDE OR ELEVATION
WITHOUT THE NECESSITY OF A VIEW OF THE HORIZON BEING OBTAINED;" in which
said Letters Patent there is contained a proviso obliging me, the said William
Barclay, by an instrument in writing under my hand and seal, particularly to
describe and ascertain the nature of my said Invention, and in what manner
the same is to be performed, and to cause the same to be inrolled in IIis
Majesty's High Court of Chancery within two calendar months next and
immediately after the date of the said in part recited Letters Patent, as in
and by the same, reference being thereunto had, will more fully and at large
appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
William Barclay, do hereby declare and specify that the nature of my said
Invention, and the manner in which the same is to be performed and carried
into effect, is described and set forth in and by the Sheet of Drawings hereunto
annexed, and the following description thereof, that is to say :-
My improvement consists in using alcohol or any other fit liquid, partly
filling a vertically-held hollow annular or ring-formed trough or cavity
formed in glass, or in some other transparent substance, in order, by means of
the equally elevated tops of the alcohol (as respects the horizon) in the
opposite branches or sides of the said ring-formed trough, as compared with the
elevation of the axis of a telescope (or of plain sights) attached to a portable
instrument to fix and correctly read off afterwards the angle of altitude or
elevation of the said axis, a line of sight at the moment of making an observa-
tion, and I effect this fixing of the angle of elevation, formed between the tops
of the alcohol and the line of sight of the telescope, by rendering the alcohol
immovable in its trough by a stopcock or any other suitable micans.
Fig. 1 is a front elevation of one of my said instruments, drawn to the real
size; Figure 2 is a back elevation of the same instrument with its moveable
parts standing in the same positions as in the former Figure. Figure 3
is a sectional view of the same instrument, with its moveable telescope and
parts attached thereto, standing in different positions from those exhibited
in the two former Figures, in order the more clearly to shew some parts
thereof; all the several Figures are drawn to the same scale of dimensions,
which is delineated in the Drawing; the same letters of reference are used
upon the same or corresponding parts or things in each of the Figures; and
throughout the description which follows, the said parts and things are similarly
named for the ease and convenience of reference thereunto. A is the centre
of the instrument, concentrically with which all the moving parts thereof
revolve, except the stopcock and its apparatus, which have the centre of
motion B, as will be further described herein. C is the arm carrying the
right-hand microscope (to be further mentioned herein), and D is the arm
carrying the left-hand microscope. These two arms being respectively of half
the thickness of their other parts around the centre A, as is shewn in Fig. 3,
wherein these arms are represented as broken off before reaching the micro-
scopes for avoiding unnecessary complexity in the Drawing. E, E, E, E, are
four arms connected together in the centre by the circular thick plate b (which
will be further mentioned herein), two of these latter arms, which are opposite
each other, and which, when in use, are nearly horizontal, carry on their ends
the verniers d. d, and the other two of these arms, which, when in use, are

page_text: nearly vertical, carry one at top the pinion f, for giving motion to the
divided circle G (as will be further mentioned herein), and at the bottom
one of these arms carry the clamp screw e, which latter, by means of the end
of this arm hooking loosely back under the toothed edge of the divided circle,
and by its spring, serves to clamp or fasten (whenever occasion may require);
this and the three other arms (E, E, E,) to the said divided circle, and the
opposite or top arm in like manner hooks loosely back under the edge of the
said divided circle, in order by its spring to keep these arms always in contact
with the said circle. The two arms C and D, and the system of arms E, are
centered together, and the two former move freely round on the screw a, fitting
tightly into the circular thick plate b (before mentioned), and this last-mentioned
thick plate enters and works freely in a corresponding circular hole in the
centre of the said divided circle. F, F, F, F, are the arms of the divided
circle (G), the edge of which circle is cut into fine teeth, and in these teeth
the pinion (already mentioned) works, and is turned by the milled head g
attached thereto,. for the purpose of causing the said divided circle (G) to
revolve on the centre (A) of the instrument, as will be further described
herein. H, H, H, H, in Figs. 2 & 3, is the annular plate of metal which forms
the back of the main box or body of the instrument, the inner circular edge of
this plate (1) being rebated'or grooved, as shewn in Fig. 3, it has also cut
through it the two circular slits marked h, h, in Fig. 2 (the uses of which
rebate and slits will be further mentioned herein). The said plate (H) has
soldered nearly upon its outer edge, the circular hoop I, I, of thin metal
forming the outer circuit of this main box, and carrying on its front the narrow
rim K, intended merely to give strength, and to this hoop (I) and the
back (H) of this main box there is attached, in the mauner shown in
Figs. 2 and 3, the main handle J, J, on which handle, in a vertical position,
the whole instrument is intended to bo supported in the left hand of the
observer at the time of using it; and on which main handle temporarly fixed
in a hole to fit it in a heavy stand or foot mounted on tripod screws, the
instrument may be supported at the times of examining or making its several
adjustments. L, L, is an annular thin plate of metal, seen in Figs. 2 and 3,
and a narrow ring of it in Fig. 1. And M, M, is another just similar plate,
which is seen in Figs. 1 & 3,and these two annular plates (L & M), have each
two hoops of thin metal soldered upon them, as seen at i, i. The hoops of M
slipping tightly within those of L, and by that means forming a pulley-shaped
box, the width of whose groove (intended to receive the annular glass
plates 1 and 3, to be further mentioned herein), is adjustable by means of
screws k, k, in Figs. 1 and 3. The annular back plate L, L, of the pulley-

page_text: shaped box above described, is made to move concentrically to A by its
outer edge fitting into and slipping freely round in the rebate or groove
formed in the inner edge of the annular plate H of the main box (which
already has been described herein), and this said front plate L has attached
to it by screws 1, 1, the divided circle (G), as shewn in Figs. 2 & 3. The
annular front plate M, M, of the said pulley-shaped box (L, i, M) has screwed
to it two small plates :N, N, which carry the studs or short pillars O,
supporting the telescope P, P, and its attached spirit level. Q. The said front
plate (M) has also screwed to it the small plate R, carrying the stud tube S,
into which is tightly slided the tubular forked arm T, T, T, carrying the
gimbols of the small lamp U, shewn in Figure 5, whose uses will be further
described herein, and the said front plate (M) likewise has screwed to it the
plate V, carrying the tubular arm W, and the traversing handle X, to be
grasped by the right hand whilst making an observation, and during the time
that an observation is making, the top of the fore fingers of the observer's
said right hand is intended to enter the short open tube Y, which acts as a
handle to the stopcock (B), in order to open, regulate, and again shut the
said cock, as will be further mentioned herein, the stud Z adjustables screwed
on to the plate V being touched by the tip of the said finger through
the opening in the bottom of the said short tube Y at such time as the
stopcock is shut or nearly so, and of which shutting or closing of the aperture
of the cock this stud is intended to apprize him in a tangible manner whilst
his eyes are otherwise employed. The tubular part of the forked arm Thas
soldered through it crossways another tubular arm m, and this cross tube (m)
by entering a corresponding slit, shewn in the end of the stud tube S, prevents
the said tubular arm T from revolving or turning round in the said stud tube
S, and so keeps the gimbols of the lamp U always nearly opposite to the middle
of the telescope. Into the tubular arm (m) a smaller tubular armi n; 'n,
(which is bent at right angles) tightly slides, and is kept from revolving or
turning round therein by a short pin p, which enters a slit in the end of the
said tube m. The small tubular arm n carries at its outer end a circular thin
concave plate of metal q, 9, (straightened if necessary by a narrow rim,) and
suspends the same before the object end of the telescope (P), a circular hole
being cut out in the centre of this plate of equal size with the diameter of the
telescope tube, and the side of such annular plate (7) next to the telescope is
painted white, or else polished, in order that the same may act as a reflector
for throwing sufficient light radiating from the lamp (U) down the tube of the
telescope to render its focal cross wires visible whilst making an observation in
the night. In Figure 1 a short and inverting eye-piece of the common

page_text: construction is represented as attached to the telescope (P), with a darkly
coloured glass screwed on before it for making solar observations; but when
the telescope (P) is required not to invert but represent objects naturally or
direct, a longer and compound eye-piece may be substituted for this short
one. In Figure 4 is represented the manner of applying a common inverting
diagonal eye-piece to the telescope P, or instead of such inverting eye-piece
a longer and direct one may be substituted; a finder or searcher for the
object intended to be thus diagonally observed is also shewn attached, wherein
r is the diagonal mirror, and s a darkly coloured glass, hinged and opening
like a door out of the way when the moon or other moderately bright objects
are to be observed. The microscope arms C and D in Figure 2, which
already have been mentioned herein, are each of them similarly enlarged
towards their outer ends, and have holes cut through them there, through which
the verniers d, d, are seen and the angle read off. By tightening screws t, t, and
their slots, these microscope arms (C & D) are fastened to the vernier arms
E, E, lying beneath them, after being first adjusted by means of the four
adjusting screws u, ut, u, u, attached by their studs to the vernier arms (E, E),
which act against the studs r, r, affixed on the microscope arms. The ends
of the arms C & D carry the short compound microscopes w, w, which are of
the common construction, having focal cross wires acting opposite to the
slits h, h, in the plate H already described, and intended (not for reading the
vernier divisions, but) for viewing the tops of the alcohol in the circular glass
trough to be further described herein.
In Figure 3 x represents one of the two magnifyers or simple micro-
scopes, which are suspended before the back of the instrument, Figure 2 (but
are not shewn there for avoiding confusion), facing the verniers (d, d), and
capable of a sufficient motion on the centre screw a for perpendicularly
reading the coincidences thereof with the divisions of the divided circle (G) in
every part of the verniers. These magnifiers x are fixed in the tops of
irregular cones of thin metal (y, y) the insides of which cones being painted
white they serve as reflectors for throwing sufficiency of the daylight
coming through the instrument between its arms upon the vernier and
divisions of the circle for the convenient reading off therefrom, and in the
night, when the lamp (U) is used, these conic reflectors (y, y,) are alike
useful in illuminating the vernier and divisions.
EL
In Figures 1 and 3, Number 11 represents a thick annular plate of ground
and polished glass or other transparent substance. In one side of this thick
annular plate (1) a circular trough or cavity 2, 2, has been ground out and
polished insile, whose transverse section is a semicircle, or soine convenient

page_text: segment of a circle or other like curve, and 3, 3, is a thin annular plate of
ground and polished glass, closely cemented upon the said thick plate (1), so,
as to form between these two plates of glass a transparent annular plate
trough for containing alcohol or some other fit liquid. I do not, however,
confine myself to the above-described mode of constructing my transparent
troughs, but sometimes bend round and form a hollow glass ring, and some-
times use two narrow annular plates of glass of different diameters, and
cement these between two other and wider thin plates of glass, thereby to
form troughs or grooves with square or rectangular sections. The stopcock (B,
already mentioned herein) is formed by grinding a conical hole through the
thin and the thick plates of glass (3 and 1), largest in the thinnest plate, and
intersecting the internal trough or groove, as is seen in Figure 3, and inserting
and grinding therein a socket of glass, 4, or of any fit metal, and fitting and
grinding within this a plug B, B, of any fit metal, of considerably greater
length than the thickness of the glass plates, and on to the smaller and projecting
part of this plug (1) a metal hoop 5, 5, is fitted, and fastened by a screw, there
being under this hoop a spring constantly tending to draw up the plug of the
cock, and so keeping the plug always in close contact with the socket (4),
and preventing the cock from leaking; the bottom plate of the short open
tube Y (already described herein) is attached to the hoop 5. In order to
adjust my said instrument for use, the first thing to be done is to examine
whether the line of collimation of the telescope P be parallel to its attached
spirit level, and, if necessary, to correct the same by the usual methods; then.
set or hold the instrument in a vertical position by its handle (J), open the
stopcock (B), and by means of the traversing handle (X), bring the
telescope into a true horizontal position, so that the bubble of the level may
exactly rest in the middle of its tube, and then shut the stopcock; then
by applying the fingers to the milled head g of the pinion, bring the zeros
of the vernier (d), and of the divided circle (G), to coincide and fix
these vernier arms by the clamp screw (e). The next thing to be done
to bring the two microscopes (w) into a parallelum with the axis of the
telescope (P), and to effect this, loosen the screws a and t, and then, by turning
first one and then the other of the adjusting screws u, bring the cross wires in
the microscopes (w) both to coincide at the same time with the apparent
bottoms of the concavities in the tops of the columns of alcohol inclosed in the
glass trough (2), and as seen through the slits (h, h,) in the plate II; and,
having accomplished this, again tighter the screws (a and t) and unclamp the
screw, and the adjustments are complete, and the instrument ready for
observing. In order to observe an altitute, take the instrument in the left

page_text: hand by the main bandle (J), and applying the right hand to the traversing
handle (x), by the action of the forefinger in the short tube (Y), open the
stopcock (B), and then, by means of this handle (X), elevate or depress the
object end of the telescope (P) at the same time that the eye is applied to
the eye-piece, until the cross wires of the telescope are found nearly to intersect
the object, and then begin gradually (as herein-before has been mentioned) to
close the aperture of the cock during the time that the wires of the telescope
are bringing into a complete coincidence with the object, and then entirely
close the cock, by which means the alcohol will become stationary and
immovable in its trough. Then, turning to the back of the instrument, by
means of the milled head g raise or depress the right-hand microscope (w)
until its cross wires coincide with the apparent concavity of the top of the
alcohol; and then, by means of the magnifier x, read off and write down the
angle indicated by the right-hand vernier; then, in like manner, bring the
other or left-hand microscope to intercept the apparent concavity of the
alcohol, and read off and write down the angle shewn by its vernier, and half
the sum or mean of these readings will be the true angle of elevation observed
by the telescope.
In the foregoing description of my said instrument I have described and
drawn an instrument such as I have found convenient in size, arrangement,
and proportion of its parts, but I do not limit myself in these particulars; and
although in order more clearly to describe my said instrument I have
described and shewn many parts and things which are already well known
and in use, I do not claim under the herein-before in part recited Patent any
Invention or exclusive use of such parts or things separately or apart, but only
as the same are or may be combined and applied in the manner herein-before
described for carrying my said Invention into effect. And I do hereby
expressly ascertain and limit my claims to the following particulars, that is to
say, to the retaining and immovably fixing of the alcohol or other fluid in its
transparent trough (2) at the moment of making an observation by means of
the stopcock (B), or by any other suitable means, and to the destroying of the
vibrations and regulating at pleasure the motions of the alcohol in its trans-
parent trough, by diminishing or enlarging of the aperture through which
the said alcohol bas to pass by the said cock, or any other suitable means.
In witness whereof, I, the said William Barclay, have hereunto set my
hand and seal, this Thirtieth day of September, in the year of our
Lord One thousand eight hundred and twenty-five.
WILLIAM (L.S.) BARCLAY.

page_text: AND BE IT REMEMBERED, that on the Thirtieth day of September, in
the year of our Lord 1825, the aforesaid William Barclay came before our
said Lord the King in His Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein contained and specified, in form
above written. And also the Specification aforesaid was stamped according to
the tenor of the Statute made for that
purpose.