IMPROVE- MENTS IN INSTRUMENTS FOR TAKING ASTRONOMICAL AND OTHER OBSERVATIONS
Year: 1863

page_text: LETTERS PATENT to Richard Archibald Brooman, of 166, Fleet Street,
in the City of London, Patent Agent, for the Invention of "IMPROVE-
MENTS IN INSTRUMENTS FOR TAKING ASTRONOMICAL AND OTHER OBSERVATIONS."
- A communication from abroad by Charles Emmanuel, of Levallois,
France.
Sealed the 26th April 1864, and dated the 28th October 1863.
PROVISIONAL SPECIFICATION left by the said Richard Archibald Brooman
at the Office of the Commissioners of Patents, with his Petition, on the
28th October 1863.
I, RICHARD ARCHIBALD BROOMAN, of 166, Fleet Street, in the City of
London, Patent Agent, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN INSTRUMENTS FOR TAKING ASTRONOMICAL AND OTHER
OBSERVATIONS," to be as follows:-
This Invention consists of an astronomical instrument termed by the inventor
a "pantoscope," in which three instruments, viz., a theodolite, an equatorial,
and an ecliptic instrument are combined, that is to say, it affords the means of
ascertaining immediately the position of the heavenly bodies in relation to the
horizon, the equator, and the ecliptic. With regard to its being a theodolite
and an equatorial it combines and simplifies these two instruments; with regard
to its being an ecliptic instrument it is entirely new, for no instrument has
hitherto been constructed to indicate or ascertain the latitudes and longitudes
of the heavenly bodies, that is to say, their position in relation to the plane of
the ecliptic.

page_text: The general construction of the instrument will be understood on reference
to the accompanying Drawing.
The chief parts of which it is composed are a graduated semicircle K and
'two graduated circles A and B, the latter of which supports a telescope or
other similar instrument L. The circles A, B,,are always perpendicular to
each other, and are free to receive the inclinations required by the latitude of
the place and the obliquity of the ecliptic; each of them is also free to turn
round the rod which sustains it. D, C, M, are three indexes or verniers for
indicating angles on the two circles A, B, and the semicircle K respectively;
N is a liquid level, and P, screws for verifying the vertical position of the
instrument; S is a compass for guiding the semicircle K into the plane of
the meridian. The circle A can occupy a position parallel to the horizon, the
equator, or the ecliptic. In addition to being graduated, its circumference is
marked with the twelve signs of the zodiac, and with fixed points to indicate
the principal stars of the equator. a, a, is the diameter of the circle A, which
is inclined at an angle of 23° 28′ in round numbers, in a slide; d is a
collar, by means of which the circle A turns on its own centre; is a
pressure screw to raise or lower in its groove the pin which allows the circle A
to be inclined to 33° and returned to its natural position. The circle B is
free to turn. A vertical style x placed on the top of this circle denotes the
time on the small plate y of the circle. The telescope L is free to turn on the
centre of the circle B, and carries the pointer C with it; F is a small fixed
circle to preserve an indication of the position of the meridian, and f is a pointer
of that circle, free to turn with the central rod which supports the circle A and
which enters the sheath g; G is a toothed sector, worked by a screw H, and
serving to incline the instrument according to the latitude of the place of
observation. When the index M of the semicircle K is at zero on the
graduation, the circle A is horizontal, it coincides with the plane of the
horizon, because, being parallel to it, it has like it the zenith and the nadir for
poles. The circle B is vertical, and as it is free to turn round the central
axis of the instrument it coincides successively with all the vertical lines of
the heavens, while the telescope which it supports at its centre always
describes horizontal circles. The instrument in this position represents a
theodolite, and serves to measure azimuths, meridional heights, and all other
heights above the horizon, to take the parallax of a terrestrial object, and for
use generally as ordinary theodolites. When by means of the mechanism G, H,
the index M of the graduated semicircle is led over the figure indicating the
latitude of the place of observation, the central axis of the instrument takes
the same direction as the axis of the earth. The circle A coincides with the

page_text: plane of the celestial equator, for it has the same two poles, the arctic and
antarctic. The circle B is a horal circle, and the telescope, whatever be its
inclination, describes circles parallel to the equator. The instrument is there-
fore in this position an equatorial, and may be employed to measure declina-
tions and right ascensions, and to ascertain the solar hour or the sidereal
hour by the horal angle of the sun or of the stars.
Lastly, when the circle A is inclined at an angle of 23° 27' 26"-76 (for the
year 1863), it coincides with the ecliptic, because the two planes, which are
parallel, have the same axis and the same poles, or the poles of the terrestrial
orbit. The circle B turning on its pivot corresponds successively to all the
circles of latitude of the heavens, and the telescope L describes circles parallel
to the plane of the earth's orbit. The instrument is therefore now an ecliptic
instrument, and may be employed to ascertain the latitude of the heavenly
bodies, and the angle which their circle of latitude makes with the meridian
of the place. It also indicates the longitudes of the heavens by the means
about to be described. For this purpose I mark on the circle A, which is
already divided into 360 degrees, the twelve signs of the zodiac, one of which,
that of the Ram, contains the point from which the longitudes and right ascen-
sions commence. The graduated circle is thus divided into 12 parts equal to
the 12 divisions of the celestial ecliptic, which is nothing but the trace in the
sky of the plane of the orbit which the earth describes in 12 months round the
sun. If, then, the zodiac of the graduated circle be made to correspond to
the celestial zodiac, the two equinoxes of the one facing the two equinoxes of
the other, the instrument indicates the places where each of the constellations
commences and finishes, and therefore denotes the longitudes. By making the
rod which supports the circle, and which is always parallel to the earth's axis,
turns in its sheath 9, the axis of the circle will describe round a prolongation
of the rod a cone in every way similar to the cone which the axis of the
celestial ecliptic seems to describe in a day round the earth's axis. The plane
of the graduated circle occupies successively all the various positions that the
ecliptic seems to occupy in 24 hours above the horizon. Or if the circle be
moved by clockwork at a speed proportional to the speed of the earth's rotation,
its twelve divisions will always coincide with the 12 divisions of the ecliptic.
It is evident that the same means which give a direct indication of the
Jongitudes of the heavens when the instrument acts as an ecliptic instrument,
ought to give indications of right ascensions when it acts as an equatorial.
Two of the signs of the zodiac, the Ram and the Balance, have always one of
their points situated in the plane of the celestial equator. If, then, the vernal
point of the instrument be made to correspond to the celestial equinox, (the

page_text: zero of right ascensions), which may be easily done by marking on the graduated
circle points corresponding to the principal stars of the equator, the right
ascension of the heavenly body observed will be indicated on the circle.
The instrument before described may be used in its entirety as a theodolite,
an equatorial, and an ecliptic instrument, or it may be constructed for use for
one or two of those purposes only. Instead of the circles A and B, semi-
circles may be employed.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Richard Archibald Brooman in the Great Seal Patent Office
on the 28th April 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, RICHARD
ARCHIBALD BROOMAN, of 166, Fleet Street, in the City of London, Patent
Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-eighth day of October, in the year of our
Lord One thousand eight hundred and sixty-three, in the twenty-seventh year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Richard Archibald Brooman, Her special licence that I, the said
Richard Archibald Brooman, my executors, administrators, and assigns, or such
others as I, the said Richard Archibald Broonian, my executors, adminis-
trators, and assigns, should at any time agree with, and no others, from
time to time and at all times thereafter during the term therein expressed,
should and lawfully might make, use, exercise, and vend, within the United
Kingdom of Great Britain and Ireland, the Channel Islands, and Isle of
Man, an Invention for "IMPROVEMENTS IN INSTRUMENTS FOR TAKING ASTRO-
NOMICAL AND OTHER OBSERVATIONS," (communicated to me from abroad by Charles
Emmanuel, of Levallois, France,) upon the condition (amongst others) that I,
the said Richard Archibald Brooman, my executors or administrators, by an
instrument in writing under my, or their, or one of their hands and seals,
should particularly describe and ascertain the nature of the said Invention,
and in what manner the same was to be performed, and cause the same
to be filed in the Great Seal Patent Office within six calendar months
next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Richard Archibald Brooman, do hereby
declare the nature of the said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and by the

page_text: following statement thereof, reference being had to the Drawings hereunto
annexed, that is to say:-
This Invention consists of an astronomical instrument termed by the inventor
a "pantoscope," in which three instruments, videlicet, a theodolite, an equa-
torial, and an ecliptic instrument are combined, that is to say, it affords the
means of ascertaining immediately the position of the heavenly bodies in
relation to the horizon, the equator, and the ecliptic. With regard to its
being a theodolite and an equatorial it combines and simplifies these two
instruments, with regard to its being an ecliptic instrument it is entirely new,
for no instrument has bitherto been constructed to indicate or ascertain the
latitudes and longitudes of the heavenly bodies, that is to say, their position in
relation to the plane of the ecliptic.
The general construction of the instrument will be understood on reference
to the accompanying Drawing.
The chief parts of which it is composed are a graduated semicircle K and
two graduated circles A and B, the latter of which supports a telescope or
other similar instrument L. The circles A, B, are always perpendicular to
each other, and are free to receive the inclinations required by the latitude of
the place and the obliquity of the ecliptic; each of them is also free to turn
round the rod which sustains it. D, C, M, are three indexes or verniers for
indicating angles on the two circles A, B, and the semicircle K respectively;
N is a liquid level, and P, screws for verifying the vertical position of the
instrument; S is a compass for guiding the semicircle K into the plane of
the meridian. The circle A can occupy a position parallel to the horizon, the
equator, or the ecliptic. In addition to being graduated, its circumference
is marked with the twelve signs of the zodiac and with fixed points to indicate
the principal stars of the equator. a, a, is the diameter of the circle A, which
is inclined at an angle of 23° 28′ in round numbers in a slide; d is a collar,
by means of which the circle A-turns on its own centre; eis a pressure screw
to raise or lower in its groove the pin which allows the circle A to be inclined
to 33° and returned to its natural position. The circle B is free to turn.
vertical style placed on the top of this circle denotes the time on the small
plate y of the circle. The telescope L is free to turn on the centre of the
circle B, and carries the pointer C with it; F is a small fixed circle to
preserve an indication of the position of the meridian, and f is a pointer of that
circle, free to turn with the central rod which supports the circle A and which
enters the sheath g; G is a toothed sector, worked by a screw H, and serving
to incline the instrument according to the latitude of the place of observation.
When the index M of the semicircle K is at zero on the graduation, the
A

page_text: circle A is horizontal, it coincides with the plane of the horizon, because, being
parallel to it, it has like it the zenith and the nadir for poles. The circle B is
vertical, and as it is free to turn round the central axis of the instrument, it
coincides successively with all the vertical lines of the heavens, while the
telescope which it supports at its centre always describes horizontal circles.
The instrument in this position represents a theodolite, and serves to measure
azimuths, meridional heights, and all other heights above the horizon, to take
the parallax of a terrestial object, and for use generally as ordinary theodolites.
When by means of the mechanism G, H, the index M of the graduated semi-
circle is led over the figure indicating the latitude of the place of observation,
the central axis of the instrument takes the same direction as the axis of the
earth. The circle A coincides with the plane of the celestial equator, for it
has the same two poles, the arctic and the antarctic. The circle B is a horal
circle and the telescope, whatever be its inclination, describes circles parallel to
the equator. The instrument is therefore in this position an equatorial, and
may be employed to measure declinations and right ascensions, and to ascertain
the solar hour or the sidereal hour by the horal angle of the sun or of the stars.
Lastly, when the circle A is inclined at an angle of 28° 27' 26"-76 (for the
year One thousand eight hundred and sixty-three), it coincides with the
ecliptic, because the two planes, which are parallel, have the same axis and
the same poles, or the poles of the terrestial orbit. The circle B turning on
its pivot corresponds successively to all the circles of latitude of the heavens,
and the telescope L describes circles parallel to the plane of the earth's orbit.
The instrument is thereforo now an ecliptic instrument, and may be employed
to ascertain the latitude of the heavenly bodies, and the angle which their
circle of latitude makes with the meridian of the place. It also indicates the
longitudes of the heavens by the means about to be described. For this
purpose I mark on the circle A, which is already divided into 360 degrees,
the twelve signs of the zodiac, one of which, that of the Ram, contains the
point from which the longitudes and right ascensions commence. The
graduated circle is thus divided into twelve parts equal to the twelve divisions
of the celestial ecliptic, which is nothing but the trace in the sky of the plane
of the orbit which the earth describes in twelve months round the sun. If,
then, the zodiac of the graduated circle be made to correspond to the celestial
zodiac, the two equinoxes of the one facing the two equinoxes of the other, the
instrument indicates the places where each of the constellations commences and
finishes, and therefore denotes the longitudes. By making the rod which supports
the circle, and which is always parallel to the earth's axis, turn in its sheath I,
the axis of the circle will describe round a prolongation of the rod a cone in

page_text: every way similar to the cone which the axis of the celestial ecliptic seems to
describe in a day round the earth's axis. The plane of the graduated circle
occupies successively all the various positions that the ecliptic seems to occupy
in twenty-four hours above the horizon. Or if the circle be moved be moved
by clockwork at a speed proportional to the speed of the earth's rotation, its
twelve divisions will always coincide with the twelve divisions of the ecliptic.
It is evident that the same means which give a direct indication of the
longitudes of the heavens when the instrument acts as an ecliptic instrument,
ought to give indications of right ascensions when it acts as an equatorial.
Two of the signs of the zodiac, the Ram and the Balance, have always one
of their points situated in the plane of the celestial equator. If, then, the
vernal point of the instrument be made to correspond to the celestial equinox
(the zero of right ascensions), which may be easily done by marking on the
graduated circle points corresponding to the principal stars of the equator,
the right ascension of the heavenly body observed will be indicated on the
circle as readily as its horal angle.
The instrument before described may be used in its entirety as a theodolite,
an equatorial, and ecliptic instrument, or it may be constructed for use for
one or two of those purposes only. Instead of the circles A and B, semicircles
may be employed.
And having now described the nature of the said Invention, and in what
manner the same is to be performed, I declare that I claim constructing
instruments for taking astronomical and other observations, substantially
in manner herein-before described and illustrated in the accompanying
Drawing.
In witness whereof, I, the said Richard Archibald Brooman, have
hereunto set my hand and seal, this Twenty-eighth day of April, One
thousand eight hundred and sixty-four.
R. A. BROOMAN. (L.S.)