Improvements in Apparatus for Indicating the Relative Movements of the Earth and Moon Round the Sun and Several Articles of the Ephemeris connected therewith.

摘要

18,923. Nicholas, A. B. Sept. 9. Orreries.-An apparatus for illustrating the relative movements of the sun, earth, and moon consists of a central pillar C1 to which is secured a disk B fitted with a lamp a1 to represent the sun and a radial arm E' moving around the pillar C1 and carrying a cylinder I' on which the earth K' and the moon are mounted. The whole apparatus is driven from a shalt H by motor, clockwork, or other suitable mechanism ; the arm E' is rotated through gear-wheels G1 . . . G4, the latter working in teeth round the edge of the disk B ; gearwheels I2, I3, J2, J3 rotate the tube K1 carrying the earth, and the motion of the arm M2 carrying the moon is obtained from the tube K1 by gear-wheels L2. . . L7. The axis of the earth is kept parallel to itself by an endless band N' working over two pulleys N2, N3 of equal size, one fixed to the pillar C1 and the other attached to the cylinder I'. To show day and night, a sun cover R1 having an aperture R3 to project the light upon the earth is carried by an arm S3 attached to an extension E6 of the arm E'. The arm S3 may also carry a pair of adjustable mirrors, on which shafts of light are directed by tubes R4 in the cover R', and which can be adjusted to give converging shadows behind the earth or moon respectively to aid in the correct representation of the eclipses aod phases of the moon. A pointer W1 attached to the tube K1 shows sidereal time on a dial marked on a disk J1 secured to the cylinder I1, and shows sun time on a dial on the top of the arm E1. The moon's declination, right ascension, &c. are shown by a pointer M' attached to the moon shaft M1 and moving over scales M5, M6. Several articles of the ephemeris can be read off by means of a thread F' working over suitable tables arranged on the disk B.