340 An Astronomical Machine^ the Telluriam. 



situated in one of its foci. The axis of the wheel L also carries 

 a large circular, wheel M ; next to which is placed a pinion N, 

 upon the upper end of whose axis the winch n is fixed. Q, is a 

 stout metallic axis of the same size as that which carries the 

 wheel K. These two axes pass perpendicularly through the 

 boards 1 and 3, the upper part of each axis where it comes 

 through the board 1 being situated in one of the foci of one of 

 the elliptical grooves. Upon the upper ends of these axes two 

 arms h and i are tightly fixed. Two other arms R and S are 

 fixed upon their lower ends so as to be perpendicular to h and i. 

 T is a narrow metallic plate which is connected with the arms R 

 and S by two movable joints : this plate assists in regulating the 

 motion of the machine. Into the arms h and ^, are inserted two 

 axes /and g, which pass up through a movable frame 5 6 7 8 and 

 turn freely within it. The lower ends of these axes project into 

 the elliptical grooves in the board 1 and slide along these grooves 

 when the machine is in motion, the arms h and i being so con- 

 trived as either to lengthen or shorten according as the distance 

 of the groove fi'om its focus increases or diminishes. 



The movable frihie 5 6 7 8 contains a number of wheels, which 

 serve to rotate the earth on its axis and give motion to the moon, 

 its nodes and apogee. A metallic supporter Y has inserted into 

 it a long and narrow socket, which passes up through a hole in 

 the plate Z. Upon the upper end of this socket a small brass 

 arm a is fixed, which holds a pinion o, whose axis forms an angle 

 of 23J degrees with the perpendicular, and carries the earth U. 

 C is a pinioi* whose axis passes up through this socket and is sur- 

 mounted by a very small wheel whose teeth act upon the leaves 

 of the pinion o. D, F, and H, are three wheels, each of which 

 is fixed upon a separate socket. The socket of the wheel D 

 turns upon the socket which is fastened into the supporter Y. 

 The socket of F turns upon the socket of D ; and the socket of 

 H turns upon that of the wheel F. Upon the upper end of the 

 socket of D a small circular brass plate c is fixed, into which, 

 near its edge, is inserted a small flattened socket, through which 

 passes a flattened wire which carries the moon V. The lower 

 end of this wire rests on another circular plate d^ which is fixed 

 upon the socket of the wheel F and has an oblique position, 

 forming an angle of 5^ degrees with a horizontal plane passing 

 through its centre. This wire is kept constantly applied to the 



