An Astronomical Machine, the Tellurium. 343 



This machine being rectified by the astronomical tables for any- 

 particular time, if the winch n be then turned from right to left, 

 the machine will exhibit the vicissitudes of day and night, vari- 

 ety of seasons, new and full moons, eclipses, anomalies of the 

 sun and moon, or year after year. 



As the earth has the same unequable motion in its elliptical 

 orbit that the real earth has, this machine will show the sun's 

 true place correctly for a great length of time. 



A table sliowing tlie dimensions of the wheels of the Tellurium, number 



of teeth, &fc. 



Wheel A, 293 teeth, 12 teeth in an inch of circum. Diam. 7.77 inches. 



Wheel B, 80 teeth, 8 teeth in an inch of circum, Diam. 3.18 inches. 



Pinion of wheel B, 8 leaves. Diam. yVtrths of an inch. 



Wheel J), 24 teeth, 8 teeth in an inch. Diam. yVirths of an inch. 



Pinion C, 8 leaves. Diam. xVu^l^s of an inch. 



Wheel E, 167 teeth, 8 teeth in an inch of circum. Diam. 6.64 inches. 



Wheel O, 25 teeth, 8 teeth in an inch. Diam. y^^yVhs of an inch. 



Wheel P, 72 teeth, 8 teeth in an inch. Diam, 2.86 inches. 



Wheel D, 36 teeth, 8 teeth in an inch, Diam. 1.43 inches. 



Wheel G, 20 teeth, 12 teeth in an inch of circum. Diam. -j^^njths of 

 an inch. 



Wheel F, 372 teeth, 12 teeth in an inch. Diam. ^^^-^ inches. 



Wheel I, 20 teeth, 8 teeth in an inch of circum. Diam. xV^^i-ths of 

 an inch. 



Wheel H, 177 teeth, 8 teeth in an inch. Diam. 7yJ^ inches. 



Wheel r, 40 teeth, 8 teeth in an inch. Diam. IfV^^ inches. 



Elliptical wheels K and L, The longer diameter of each wheel, 10 

 inches. Distance between the two foci yVV^s of an inch. Both of these 

 wheels contain the same number of teeth. 



Wheel M, 280 teeth, 8 teeth in an inch. Diam, lly*^^ inches. 



Pinion N, 16 leaves. 



Elliptical grooves in the board 1, The longer diameter of each 

 groove, measuring from the middle of the groove on one side to the 

 middle of the groove on the opposite side, 10 inches. Distance be- 

 'Ivveen the two foci yVV^s of an inch. 



