AN IMPROVED ASTRONOMICAL INSTRUMENT FOR EXHIBITING THE POSITION OF THE HEAVENLY BODIES WITH RELATION TO THE EARTH
Year: 1873

page_text: PROVISIONAL SPECIFICATION left by Walter Marsham Adams at the
Office of the Commissioners of Patents, with his Petition, on the
1st September 1873.
I, WALTER MARSHAM ADAMS, B.A., late Fellow of New College,
Oxford, of the Arundel Club, Salisbury Street, Strand, in the County
of Middlesex, do hereby declare the nature of the said Invention for
"AN IMPROVED ASTRONOMICAL INSTRUMENT FOR EXHIBITING THE POSITION OF
THE HEAVENLY BODIES WITH RELATION TO THE EARTH," to be as follows:-
This Invention has for its object an instrument for exhibiting the
motion and position of the heavenly bodies relatively to any point
on the surface of the earth, and for embodying the various conceptions
necessary for nautical astronomy.
The apparatus consists in the first place of a stand carrying a globe
mounted somewhat like a sea compass, that is to say, the stand has
fixed to it a rigid vertical semicircule, at the ends of which are pivots
carrying slides which support a circular arc; a diameter of this circular
arc coincides with the axis of the globe.

page_text: The axis on which the globe is capable of revolving is a rigid wire
fixed in the above-mentioned circular arc, the globe occupies the middle
portion of the axis, and is therefore concentric with the circular arc.
Outside the globe there is a circle concentric with it, which is also
capable of revolving on the axis; this circle carrics a slide to which
a blunt pointer is fixed; the pointer has a scrow point which when
screwed out presses against the globe, thereby fixing the position of
the slide and circle relatively to the globe. The point at which the
pointer touches the globe marks the position of the observer on the
carth.
By moving the slide round the circle, and by turning the circle
round on the axis, the pointer can be set to any point on the globe.
The slide also carries two circular arcs or arms which in their turn
carry two parallel circles of which the pointer is a pole; the size
and position of these circles is such that they mark the real and
apparent horizon of the observer. These circles are split to allow of
their passing the axis. The circle corresponding with the apparent
horizon is carried by screws, so as to allow of its position being
altered to correct for the dip of the horizon. Next outside the circle
carrying the pointer is another circle concentric with it and the globe
which is also free to turn on the axis. Sliding on this circle, and
on each other, are two other "great" circles which mark the equator
and ecliptic. At the pole of the ecliptic is pivotted a quadrant of a
great circle, which is used to find the solar latitude and longitude;
or the pivot may be moved 5° from the pole, and the quadrant may
have sliding upon it a metal disc so as to mark the position of the
moon. On the ecliptic itself is a short circular arm at right angles
to it capable of sliding on it, on which slides another disc representing
tho sun. The discs representing the sun and moon can thus be slid
up or down from the ccliptic so as to show the positions of the sun
and moon at different times of the year and month, and the corrections
for refraction and paralax. The circle forming the ccliptic is made
in two parts sliding the one on the other; one part is marked with
the zodiac, and the other with the month. Outside the circle carrying
the equator and ecliptic, and concentric with it, is a spherical framc-
work of wire, cach wire being a meridian circle. These wires carry
star-shaped plates of metal representing the principle stars or the

page_text: constellations; halves or other portions of the wires may be cut away
for convenience sake.
The spherical framework may be made in two halves united by
screws, so that it can be removed at pleasure.
All the bearings of the circles on the axis, and all the slides, may
carry set screws, so that any of the circles may be set to the axis
independently of the others, and the slides set on the circles. The
circles may also be graduated.