Star-Following with Table Stands. 291 



Milder bearing, c, is open like the letter u, so as to allow the 

 spindle and disc to be raised clear of the cone ; it is furnished 

 with a little wedge which, when pushed in, lifts it up thus : — 

 Now to use this stand, the disc being kept free 

 from touching the cone by means of the little 

 wedge which is pushed in, the cord is passed 

 completely round one of the grooves of the 

 sheave e (either over or under according to the 

 motion of the star to be observed) . The stand is 

 moved right or left by hand, and the altitude attained by the 

 long screw. As soon as the star is found the little wedge is 

 drawn back, and the disc is now pressed by the force of the 

 elastic band against the cone, aided also by the weight at the 

 end of the cord, and by the friction thus produced, the disc 

 and cone now move together; thus the two movements in 

 azimuth and altitude are simultaneously produced by turning 

 the winch d ; and their relative velocities are adjusted by 

 sliding • the disc to a larger or smaller part of the cone as 

 required. Since there are several grades to the sheave e, and 

 each may be acted upon by any part of the cone, a great variety 

 of relative speeds may be obtained to suit the rising, southing-, 

 or setting of the heavenly bodies. 



The above arrangement is found so simple and easy to work 

 with, that any further degree of independence of manual action 

 is unnecessary for the amateur astronomer on his own account, 

 for with one gentle movement of one hand he can follow a star 

 in any direction; but there are cases in which a complete 

 automatic movement is desirable, as, for instance, in showing 

 the planets to a number of young people one after another. 

 The telescope once set may be kept with the object in the 

 field for a quarter or half an hour by a very inexpensive mover, 

 although ^hitherto such a luxury has been confined to the 

 possessors of costly equatorial mountings, with equally ex- 

 pensive clockwork to keep them moving. 



The prime mover to accomplish it is a plain moderator lamp, 

 such as may be bought, without stand, globe, or chimney, for 

 ten shillings. The wick-tube with the smaller rack and pinion 

 is removed, and on the top of the little oil-pipe is soldered a 

 very small gas-jet with stopcock, through which the oil may 

 escape faster or slower as desired. The lamp filled with pure 

 fine colza oil is attached to the slab of slate on the left-hand 

 side and about a foot below it. Another pair of sheaves are 

 now fitted, one to each of the blocks of wood on the slab ; 

 another piece of whipcord is used ; one end of it is tied to the 

 rack of the lamp which rises two or three inches when the lamp 

 is wound up ; it then passes over the two sheaves across the slab, 

 and hangs down on the right side with another weight attached. 



VOL. V. — NO. IV. X 



