Patent GB-190407303-A (GB)
Title: Improvements in Tellurians.
Inventor: EPES THEODORICK PRYOR
Filed: 1904-03-26
Granted: 1904-05-05
Abstract: 7303. Epes, T. P. March 26. Orreries.-Relates to apparatus for illustrating the phenomena dependent on the relative movements of the sun, earth, and moon. The sun is represented by a lamp S, the earth by a globe E, and the moon by a globe M. The annual revolution of the earth is produced by an arm A which turns on an axle A<1>, and the daily rotation by a pulley B fixed to the flexible shaft forming the axis of the earth and driven by a band c from a pulley C fast on the axle A<1>. The inclination of the earth's axis is produced by setting a journal box D in which the axis turns, at the proper angle between two flanges J on a guide-wheel G, which rotates on the arm A. The box D is fixed by a pivot pin d and an adjustment pin d<1>. The earth's axis is kept parallel, during the year, by means of the wheel G, which is driven by a band g from a wheel H of equal size fixed on the shaft A'. The moon globe M is carried by an arm K fixed to a pulley M' which turns on a hollow spindle L projecting from the box D. The pulley M' is driven by a wheel N on the shaft A<1>, which wheel is eccentric on its axis, the eccentricity being equal to the horizontal distance between the centres of the pulleys M', B. The inclination of the moon to the ecliptic is provided for by making the spindle L on which the pulley M' rotates, at an angle of about six degrees with the axis of the box D. By turning the box D on its longitudinal axis, the retrogradation of the moon's nodes may be shown. For this purpose, the box D is made square with holes through it in both directions for the pins d, d<1>, or it may be round and may then have a larger number of holes. The lamp S is mounted on an arm 1, the other end of which supports a tube 3 so placed that a pencil through the tube is directed to the centre of the earth all the year round. To effect this, the arm 1 is mounted eccentrically on pins 24, 25 on two wheels w, y of equal size connected by a band. The eccentricity of the pins 24, 25 is equal to that of the earth's centre with respect to the axis of the wheel G. The disc shown in Fig. 5 is placed on the tube 3, and serves to show the equinoxes and solstices. The disc shown in Fig. 6 tells sunrise and sunset during the rotation of the earth, variation in time, twilight, &c. The disc in Fig. 7, when the slot is horizontal, traces the ecliptic, and, when the slot is vertical, shows the artic circles and the play of light beyond the poles. The disc shown in Fig. 8 in provided with a slotted projection 33 which embraces a guide-pin 15 supported on the arm A. The disc, therefore, oscillates as the arm 1 swings, and the slot 32, which always remains parallel to the earth's axis, will show the noon meridian, the variation in time at different places, &c. The results of variation in the inclination of the earth's axis may be shown by means of a globe mounted on a spindle attached to a graduated quadrant adjustably supported on a standard. This standard is mounted on the guide-wheel G with eccentricity equal to that of the pins 24, 25 on the arm 1. Precession of the equinoxes may be shown by slightly increasing the size of the wheel H, as by putting a rubber band into the groove, or by employing a wheel with two grooves, one slightly larger than the other.