ASTRONOMY IN WANSTEAD. 153
Huygens' Telescope 1684.
Explanation:—a b. The pole or mast. a. Pulley at top of pole, c d. Upright carrier running
in a slot bearing, e. An arm at right angles, to which is attached f f. A platform.
g g. Rope attached to each end of the carrier, h. Leaden weight to balance I Cylinder
containing the object-glass, K L. Rod affixed to cylinder. M. Brass 'cup-and-ball' joint ;
the end of the cup to be placed in a hole in the platform ; the ball is attached to the rod K.
N. Leaden weight, to which is attached a copper wire running to. L. End of wire, to which
the cord is affixed. O. Tube containing the eye-piece, attached to P Q. A jointed rod,
R. Handle held by observer. S. Small leaden weight. T. A winch for winding the lower
end of cord, u. A runner with notch for the cord. V L. The (thin silk) cord "filum tenue
bombycinum." X. Rest used to steady the observer's hands. V. Lantern.