An Improved Instrument for Determining an Observer's Position at Sea or on Land, and for Determining the Deviation of the Magnetic Compass at any Point.
Year: 1891

page_text: Date of Application, 1st Dec., 1891-Accepted, 9th Apr., 1892
COMPLETE SPECIFICATION.
An Improved Instrument for Determining an Observer's Position at
Sea or on Land, and for Determining the Deviation of the
Magnetic Compass at any Point.
I, WILLIAM HENRY BEEHLER, of No. 204 Lexington Street in the City and
County of Baltimore, State of Maryland, U.S.A., a Lieutenant in the United
States Navy, 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:-
I have designated this instrument as a solarometer, an instrument to measure
with the sun.
astronomy.
The solarometer is constructed upon the scientific principles of nautical
Observations of the sun, moon, stars, and planets may be made with the
solarometer independent of the visibility of the sea horizon and at any time any
celestial object is visible in the sky.
At the instant of an observation, the solarometer indicates by its graduated
arcs the observer's exact latitude, the hour angle of the body observed, and the
true direction of the local meridian, without any calculation. By comparison
with a chronometer regulated to Greenwich time, and by comparison with the
compass the observer ascertains his longitude and total compass error respectively.
The solarometer may also be used to rate chronometers, especially when the
latitude and longitude are accurately known.
The solarometer must be used with a nautical almanac, a book of azimuth tables
and a chronometer. The book of azimuth tables contains the true bearing of
heavenly bodies for every ten minutes of local apparent time, for every degree of
latitude up to 65 degrees north and south, and for every degree of declination to
include the declinations of all bright stars. A book of azimuth tables is to be
published for use with the solarometer.
"
Referring to the accompanying drawings for a more complete explanation of my
invention,-
Figure 1 is a side elevation of my apparatus.
Figure 2 is a sectional elevation of a part of the apparatus showing telescopes.
Figure 3 is a cross section of telescope showing rings and cross hairs.
Figure 4 is a plan view.
Figure 5 is a transverse section of polar bracket and support R.
Figure 6 is an enlarged detail view showing the crossing of the circles D and E.
Figure 7 is a cross section of E at the crossing of D.
Figure 8 is a view showing the connection of the arc Z and the supplemental
are Za
Figure 9 shows connection of the arc D with auxiliary arc D.
Figure 10 is a view of a modified and simplified solarometer for use on land and
in which no float is necessary, the other features being essentially the same.
The solarometer consists of a stand supporting a constant level base, which
sustains a system of concentric spheres, arcs and fittings.
HH is a flat graduated ring supported upon the brackets C C attached to the
rod R.
The ring H H is supported so that it is constantly level and it is therefore an
artificial horizon. The centre of the ring H H is in the prolongation of the axis
of the rod R. The ring H H is fitted with four spirit level bulbs HI' countersunk
in its face, these indicate any deviation from the true level.
The rod R projects vertically upward from a float K' which is supported in

page_text: mercury contained in a spherical bowl K. This bowl is supported by gimbals upon
the upper end of an upright post or pillar which is secured to the deck of the
vessel, and by these means the motions of the vessel are prevented from communi-
cating themselves to the apparatus which is supported from the float.
The bowl K is made spherical to a point about of its diameter, the upper
being cut away to form an opening or mouth whose edges terminate in a short
vertical cylindrical extension with a flat rim or lip.
The float has the form of a hemisphere with a frustum of a cone. The float is
arranged so that when the bowl K is level the horizontal section of the hemi-
spherical portion lies in the horizontal central plane of the bowl, while the truncated
portion of the float is immersed in the mercury. The weights of the float and
apparatus sustained thereby are regulated to equal that volume of displaced
mercury.
Ring upon the outer surface of the float, and q' and upon the inner surface
of the bowl, at equal distance above and below the centre, limit the inclination of
the float with respect to the horizontal central plane of the bowl. These rings,
together with the short cylindrical extension and lip at the mouth of the bowl
constitute a fermeture to keep the mercury in the bowl in case of extraordinary
violent heeling of the ship. If this should occur to such an extent as to bring these
rings in contact no observation should be taken with the instrument, because it
might then not be perfectly level.
The greater part of the effect of the motion of the ship is annulled by having
the solarometer placed amidships, and by the gimbal supports of the spherical
bowl.
The mobility of the large quantity of mercury insures an accurate level flotation
for the flat surface of the bottom of the float.
The rod R is fixed in the exact vertical line above the centre of the Hoat. [t
has a ring to which the lower ends of the brackets C C are attached, see
Figure 1.
BB is a flat vertical ring which forms the polar bracket. It is a semi-circular
ring having bearing surfaces at its ends, 180 degrees apart to support the polar
axis P P.
The centre of the polar bracket B B is in the exact vertical prolongation of the
axis of the rod R. This centre is also the common centre of the entire system of
ares and of the sphere. The polar bracket B B is graduated into degrees and
fractions. The zero mark is in the middle of the semi-circumference and it is
marked on each side up to 90 degrees at the ends.
The bracket B B fits into a slot in the top of the rod R, and it has its interior
curved edge formed into ratchet teeth which are engaged by the pinion B' mounted
upon a shaft extending through the slotted part of the rod R, and having disks
upon its outer ends. By turning these disks and shaft the pinion which engages
the ratchet teeth will act to move the polar bracket in either direction within the
slot and thus depress or elevate either pole.
The outer edge of the bracket B B is slotted to form a guide for the rib which
projects upward from the bottom of the slot in the rod R, as shown at B²
Figure 5.
Near the extremities of the bracket B this slot is cut through the ring to permit
the pins A under the horizon ring to pass through. The pins A hold the polar
bracket in the plane passing through the zero points of the graduated ring H H.
There is a set screw 133 in the side of the rod R to clamp the polar bracket B in
any desired position.
S is a stellar sphere made of any suitable light material.
It is supported upon
the polar axis P P at the poles around which it is free to revolve.
The centre of the stellar sphere S is in the vertical prolongation of the axis of
the rod R, and this centre is the common centre of all the other dependent ares
and rings.
The circle M M has the shape of a segment of a concentric sphere, larger in

page_text: diameter than the sphere S. It is supported upon the polar axis P P with
bearings free to revolve around the poles over the surface of the stellar sphere S.
The ring M M is the meridian ring and it may be moved to stand in the plane of
any of the meridians of the stellar sphere. It has a longitudinal slot in the middle
of its outer surface to receive the pins A which project under the horizon ring H H
and through the polar bracket B B.
The pin at the lower end of the bent arm W depending from the azimuth
arc Z, to be hereafter described, also enters the slot in the meridian ring M M
so that the meridian ring M is confined in the plane of the local meridian when an
observation is taken.
The slot in the edge of the polar bracket B B is cut through from near the poles
to points about 65 degrees from the poles. In zero latitude on the equator the
poles lie in the horizontal plane of the horizon ring, but the pins A are attached
underneath that ring below the horizontal plane by the amount due to the
thickness of the ring. In practice the solarometer will not be used generally in
higher latitudes than 65 degrees.
The equatorial ring E has the shape of a segment of a concentric sphere of
slightly greater diameter than the meridian ring M M to which it is secured by
means of the braces M, Figure 4, in the plane at right angles to the plane of the
meridian ring. The middle outer surface of the equatorial ring E has a sharp pro-
jecting knife edge. This knife edge is in the exact plane of the great circle
perpendicular to the plane of the great circle passing through the poles.
The outer surface of the equatorial ring E is graduated into 24 hours, minutes
and seconds of time, with the zero and 12 hour marks at the points of its inter-
section with the meridian ring.
Upon the edges of the equatorial ring E there are grooves E' for bearing surfaces
for the declination arc D, Figure 7.
The declination arc D is a narrow segment of a concentric sphere and of the
same diameter as the knife edge of the equatorial ring.
The declination arc is supported by bearings on the polar axis P P at the poles.
It is cut into two parts at 90 degrees from the poles to admit the knife edge of
the equatorial ring E, and it has bearing surfaces to fit the grooves on each side of
the equatorial ring.
The declination arc D has a middle longitudinal slot and it is graduated into
90 degrees and fractions on each side of the equatorial ring, with the zero mark at
the knife edge. The arc D has two tee rails ou each side of the middle longi-
tudinal slot which extend from pole to pole continuously and connect the two parts
of the declination arc D. A vernier D' is fitted to travel on these rails, the
graduations of the vernier are on one side opposite the graduations on the side of
the slot of the arc D, and show through.
At the initial point of the vernier there is a pin D perpendicular to the
tangent plane of the arc D at that point. This pin D carries a ball socket
at its end which receives the ball dependent at the end of the pin ZP, as shown
in Figures 1 and 2, and which hangs down from below the centre of the mirror or
the azimuth arc Z.
The vernier block D³ and its tangent block D have tee shaped grooves in their
lower surfaces to fit the tee rails D, and a set screw D clamps the block D' to
the surface of the declination arc D.
The tangent screw D' is supported in movable joints on the uprights t¹ so that
the screw acts in the direction of the tangent to adjust the vernier accurately in
any desired position. This construction is that in common use on sextants.
the other verniers of the solarometer are fitted similarly.
All
There is a vernier attached to one side of the declination arc D which travels on
the equatorial ring and serves to accurately locate the position of the declination
are along the graduations of the equatorial ring. Figure 6.
The azimuth are Z has the modified form of a segment of a hemisphere.
It is concentric with the stellar sphere and of the same diameter as the horizon

page_text: ring H H.
Its feet are fitted with shoulder pieces which rest upon the flat
horizon ring. A vernier with set screws and tangent screws, is attached to the
feet of the azimuth arc to adjust it in any vertical plane passing through the
zenith. The azimuth arc is free to revolve around the horizon ring H H and
pivots in the zenith by a pin on the bent arm W which engages the slot in the
meridian ring M M.
One edge of the azimuth arc Z is cut away, see Figures 2 and 4, so that the vertical
circle passing through the zenith occupies the space adjacent thereto.
The azimuth arc has a sliding carriage which supports the telescopes or tubes T
and O and the mirror T2 directly underneath the telescopes. The axis of the
telescope T and the central point or cross hairs of the mirror are in the exact
plane of the vertical circle passing through the zenith.
The mirror is plain and is fixed in the tangent plane of the vertical circle, so
that its surface makes equal angles with the axes of the telescopes T and O. These
angles are the angles of incidence and reflexion.
The pin Z is attached under the mirror in accurate prolongation of the axis of
the telescope T. This pin ZP has a ball on its end which fits into the socket of the
pin D on the declination arc and serves thus to allow the azimuth are Z and the
declination arc D to make junction at any angle.
In order to avoid the loss of light by lenses the telescopes may be replaced
by tubes T and O, which are provided with hinged shutters to move in and out
of the tubes.
These shutters are hinged near the ends of the tubes T and O. The central
apertures are fitted with fine cross wires forming an orifice about one millimeter in
diameter and one or more circies a little greater in diameter than the disc of the
sun. Fig. 3.
When the axis of the tube is in the exact direction to the centre of the sun, the
sun's disc will appear symmetrical with the fine wire circle; if the moon be observed
its visible limit will be symmetrical with a part of that circle when the axis of the
tube points direct to the moon's centre, and if a star or planet be observed it must
appear in the centre orifice of the tubes.
The aperture of the tubes facilitates finding the object to be observed, while the
sliding shutters enable an accurate observation in the exact axis of the tube T
which is in the exact direction of a radius of the sphere S, and is practically as if
the celestial body is observed at the centre of the earth.
There is a vertical support in front of the solarometer mounted amidships ou
board of a vessel, which support is fixed in the line of the vessel's keel. This
support carries a
hinged index U, Figure 4, which is free to move and rests lightly
in contact on the horizon ring HH.
In order to ascertain the latitude, longitude, and compass error by observations
with the solarometer it is necessary to proceed in the following manner:
The declination of the body to be observed is taken from the nautical almanac
for the Greenwich time of the observation given by the chronometer. The vernier
of the declination are is placed in the position corresponding to that declination.
The azimuth arc Z and the declination are D are then joined by means of the ball
and socket pins Z" and D².
The azimuth or true bearing of the body to be observed is found approxi-
mately in the book of azimuth tables corresponding to the declination of
the body to be observed, and the approximate latitude and approximate local
apparent time.
The azimuth are is then adjusted corresponding to this approximate azimuth on
the horizon ring H H. The telescope or tube T on the azimuth arc is then turned
towards the body in the sky, and in order to point the axis of the telescope or
tube T to the centre of the object it will be necessary to adjust the polar bracket B B
and the azimuth are Z. If the body appears in a direction nearer the pole than
the direction of the axis of the tube T, it will be necessary to depress the pole
by the raichet on the polar bracket B, if it appears farther from the pole then

page_text: vice versa the pole must be elevated correspondingly.
As the declination
does not change appreciably in the time necessary to make these adjustments,
the graduations of the polar bracket will show the observer's latitude accurately
when the body appears in the tube at the same distance from the pole as the axis
of the tube is. If the body appears in the sky nearer or farther from the
meridian it will be brought into exact coincidence by turning the azimuth arc by
means of its tangent screw.
When the body observed is seen exactly with its centre coinciding with the axis
of the telescope T and reflected by the mirror in the exact direction of the axis
of the telescope O, it occupies the line of the intersection of the azimuth and
declination arcs.
The celestial body cannot be seen exactly at the intersection of the azimuth and
declination ares except for one instant of time and for that latitude. Therefore,
the polar bracket must by construction show the observer's true latitude, the angle
measured on the horizon between the meridian ring and the foot of the azimuth
arc must be equal to the body's true azimuth.
The observation thus gives observer's latitude, the body's hour angle and the true
azimuth. In case of the sun, the hour angle is the local apparent time, in case
any other body be observed the local apparent time is found by reduction. The
instant of an observation is noted by the chronometer regulated to Greenwich
time and the difference between the local time found by the observation and the
Greenwich time of the chronometer is the longitude.
The index U in front of the solarometer on the horizon ring shows the true
direction in which the vessel was heading at the time of the observation, this
direction compared with that indicated by the mariner's compass will show the
total error of the compass on that course.
In order to compensate for the atmospheric refraction, the azimuth are has a
modified curvature which varies with the altitude. The curvature is such as may
be traced by radii from centres at varying distances below the centre of the sphere
corresponding to the amount of refraction at the different altitudes. The azimuth
are is also fitted with a movable counterpoise weight Z to compensate for the
weight of the sliding carriage and fittings.
To make observations of lunar distances, the solarometer is provided with
adjustable azimuth arc Z" and declination arc D". The arc Z is similar in all
respects to the azimuth arc Z except that near the zenith it is enlarged to fit over
on top of the azimuth arc Z, see Fig. 8. The bent arm W is provided with an
extra piece which projects above and fits in a slot in the zenith of the are Z.
The arc D is likewise similar in all respects to the declination arc D except
that it has forked ends to fit on to the polar axis P P and enable it to work in the
same spherical surface as the declination arc D, see Fig. 9. The arcs Z and D
have all the fittings similar to those in the arcs Z and D.
The
Two persons observe at the same time, one observes the noon while the other
observes the sun, or a star at convenient angular distance from the moon.
local time is found by both observers and to be correct both must have the same
result at the same instant. The distance between the vernier pins of D and D* is
then measured on a suitable graduated scale. This distance is the true lunar
distance at that instant of observation which should be noted by the chronometer.
By comparing this observed true lunar distance with the lunar distance predicted
in the nautical almanac the observer finds the exact Greenwich time of the
observation.
My invention is not limited to the exact form described herein but includes
simpler modifications which may be used on land. Solarometers mounted on a
permanent base with sliding carriage and telescopes on azimuth arc or on declination
On shore when the latitude and the true direction of the local meridian are
accurately known, the azimuth arc-may be dispensed with. In this case, the
sliding carriage with the telescopes or tubes T and O is adjusted on the declina-
агс.
tion arc.

page_text: Observations are made with simplified solarometers when mounted accurately
level and with its meridian circle in the exact vertical plane of the local meridian.
The sliding carriage is adjusted on the declination are corresponding to the
declination of the body to be observed as found in the nautical almanac, or as may
be marked upon the stellar sphere. The telescope is then turned towards the
body in the sky until it is seen in the exact centre of the telescopes or tubes.
If the nautical almanac is not used, fixed stars may be observed by attaching
the declination ring with its sliding carriage, to the stellar sphere at the place
where the star is marked on that sphere. This is done by means of a screw pin
under the mirror of the sliding carriage, which pin lies in the direction of the axis
of the tube and the prolonged radius of the sphere.
The simplest form of the solarometers has an additional meridian ring which
may be placed in a position corresponding to the sun's position in the sky, either
by its right ascension and declination, as given in the nautical almanac or as
approximately marked by the ecliptic on the stellar sphere. When a fixed star is
observed the declination ring is attached to the stellar sphere and its sphere and
the additional meridian ring turns with it when the telescope is turned towards the
star. The additional meridian ring will then show the sun's hour angle even when
the sun is below the horizon by the observation of the fixed star. The sun's hour
angle is the local apparent time. The equation of time is printed on a card on the
base of the solarometer and the local mean time of the instant of the observation
is found accordingly.
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-
1st. An instrument consisting of a stellar sphere supported upon a polar
bracket, graduated arcs and rings with relation thereto forming a mechanical
representation of nautical astronomical triangles mounted upon a constant level base,
with a mirror and observing tubes fitted at the junction of the declination and
azimuth arcs adjusted to the declination and approximate azimuth of the body to
he observed.
2nd. An instrument consisting of a bowl containing mercury, a float resting in
said mercury and forming a constant level base, a post or support extending
upwardly from said float, a bracket carried thereon, an artificial horizon supported
upon said bracket, a stellar sphere supported upon an adjustable polar bracket,
the meridian, declination and azimuth arcs arranged with relation to each other and
with relation to the globe, as herein described.
3rd. An instrument consisting of a bowl suspended upon gimbals and containing
mercury, a float adapted to rest in the mercury in said bowl, a polar bracket
supported and adjustable from said float, a stellar sphere suspended upon said
bracket, a horizon and meridian circles and an azimuth are in combination with a
mirror, a telescope mounted upon said carriage and an observing tube mounted upon
the same carriage and with such relation to the telescope as to cause the lines of
the axes of the telescope and observing tube to meet the surface of the mirror at
equal angles at the ball and socket junction of azimuth and declination arcs, as
herein described.
4th. The suspended bowl containing mercury and the float resting therein, the
adjustable polar bracket, stellar globe suspended therefrom, horizon, meridian and
declination rings and an azimuth ring, the curvature of which varies from that of
a circle, so that as the sliding carriage of the telescope mount is moved upon the
azimuth ring the axis of the telescope will be deviated from the prolonged radius
of the astronomical vertical circle to compensate for the apparent variation caused
by the refraction of the atmosphere, as herein described.
5th. An apparatus consisting of a central stellar sphere, exterior concentric
graduated rings and spherical segments having a common centre therewith, a
spherical mercury containing bowl with gimbals upon which it is supported from

page_text: a fixed post, a float supported in the mercury and having a post upon which the
sphere, segments and circles are adjustably supported whereby observations at sea
may be taken independent of the visibility of the sea horizon, as herein described.
6th. The sphere graduated rings and circles and a horizontal ring supporte..
upon a float so as to form a constant level base, in combination with the
independent hinged index hand attached to a vertical support in the vertical plane
of the keel of a vessel, and in front of said apparatus whereby the bearing of the
ship's head may be indicated by the graduations upon the horizon ring of the
apparatus at the instant of any observation, as herein described.
7th. An apparatus consisting of a suspended bowl containing mercury, a float
adapted to rest in the mercury in said bowl and a support on said float, au
adjustable polar bracket, a sphere suspended therein, graduated rings or circles in
segments of concentric spheres supported with relation thereto in combination
with one or more azimuth and declination arcs, carriages adjustable thereon so
that one or more telescopes and observing tubes may be mounted and adjusted upon
the apparatus so that simultaneous observations of two or more celestial bodies.
may be obtained from the single apparatus substantially as herein described.
Dated this First day of December 1891.
For the Applicant,
W. E. GEDGE,
Agent.