IMPROVEMENTS IN TELLURIANS
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Alexander Melville Clark at the
Office of the Commissioners of Patents on the 8th November 1882. A com-
munication to him from abroad by Jeremiah Spicer, of Taylor's Island, in the.
County of Dorchester, Stato of Maryland, United States of America
ALEAXNDER MELVILLE CLARK of the firm of A Mand W Clark of 53, Chancery
Lane; in the County of Middlesex, Patent Agents." IMPROVEMENTS IN TELLURIANS
A communication to him from abroad by Jeremiah Spicer, of Taylor's Island, in the
County of Dorchester, State of Maryland, United States of America
"
The object of this Invention is to produce an instrument for showing the operation
of the causes of day and night and of the seasons, which shall be exempt from
certain inconsistencies and defects that are incidental to tellurians generally, and
which may be made at such a small cost.
Ordinarily, as tellurians are made, the earth is represented as moving in an orbit
the plane of which is at right angles to the sun's axis. Consequently it is very
difficult to keep the axis of the globe parallel in order to show the changes of the
seasons. In the improved instrument I obviate this difficulty by causing the earth
to move in an orbit the plane of which is at an angle of twenty-three and one-half
degrees to the axis of the sun, which is about the angle that the "equator" and
the "ecliptic" make with each other, and simply suspend the globe, which
represents the earth, at a point that corresponds with the north pole, and depends
upon its gravity for keeping its axis vertical or parallel, with that of the sun
during its entire revolution around the sun. By this mode of suspension and by
the inclination of the plane of the earth's orbit, as hereinbefore described, nothing
is necessary to keep the axis parallel in order to show the changes of the seasons,
and the globe representing the earth may be readily turned on its own axis to
indicate its diurnal motion.
The base of the instrument or apparatus may be made of any suitable material,
size, and shape, and mounted thereon is a standard, having a spindle or pivot, on
its top, which inclines twenty-three and one-half degrees from the perpendicular or
vertical position. Said standard also serves to carry above or by an upward
extension of said pivot, a lamp or other illuminating device whose flame represents
the sun, and will here be designated as such. Arranged to rotate upon or around

page_text: the pivot is an arm, bent or constructed at its outer portion to admit of the
suspension from and within its inwardly and upwardly bent end, of a globe, which
represents the earth, and will here be designated as such. The earth is or may be
thus suspended by a short thread, or in any other free manner that will cause it
by its gravity to hang plumb, the point at which it is suspended representing the
north pole.
Froin this description it will be seen that the axis of the earth will be vertical
and always parallel during the motion of the earth in its orbit around the sun, with
the axis of the latter as represented by the center vertical line of the flame, and
that the inclination of the plane of said orbit as produced by the rotation of the
arm on the pivot will show by the light thrown upon the earth the changes of the
seasons, Thus in one position the rays of light will be seen as falling twenty-
three and one-half degrees beyond the north pole or point of the earth's suspension.
This represents the position of the earth, or northern hemisphere thereof, in summer.
On the other hand, when by the motion of the earth in its orbit, the rotating arm,
with its suspended globe, reaches the opposite position, the rays of light falling on
the earth will indicato.summer in the southern hemisphere. In this way, or as the
arm carrying the suspended earth is revolved, the light will fall upon the earth
in such manner as to show the different seasons and their intermediate changes,
Of course in an instrument of this simple construction all the natural or true
conditions of the earth and sun relatively to each other are not shown, and the
earth should be made to move in an elliptic instead of a circular orbit; nor is there
any special provision for rotating the earth on its own axis three hundred-and-
sixty-five times and a fraction, each revolution it makes around the sun; but the
manner in which the earth is carried adinits of its being turned at intervals to
_illustrate its diurnal motion and the changes of day and night, as the rays of the
-sun-fall-upon-a-constant-varying-half-of its surface, leaving its varying remaining
-half-in-the-shade.