336 PERGtTSOK'S 



LECT. tial meridian L L passes through two notches in the 

 v^x-v-v,'' north and south points of the horizon, as in a common 

 globe : but here, if the globe be turned round, the hori- 

 zon and meridian turn with it. At the south pole of 

 the sphere is a circle of 24 hours, fixed to the rings, and 

 on the axis is an index which goes round that circle, if 

 the globe be turned round its axis. 



The whole fabric is supported on a pedestal N, and 

 may be elevated or depressed upon the joint O, to any 

 number of degrees from to 90, by means of the arc P, 

 which is fixed in the strong brass arm Q, and slides in 

 the upright piece R, in which is a screw at r, to fix it at 

 any proper elevation. 



In the box T are two wheels (as in Dr. Long's sphere) 

 and two pinions, whose axes come out at V and U ; 

 either of which may be turned by the small winch W. 

 When the winch is put upon the axis V, and turned 

 backward, the terrestrial globe, with its horizon and 

 celestial meridian, keep at rest ; and the whole sphere 

 of circles turns round from east, by south, to west, 

 carrying the sun Y, and moon Z, found the same way, 

 and causing them to rise above and set below the hori- 

 zon. But when the winch is put upon the axis U, and 

 turned forward, the sphere with the sun and moon keep 

 at rest ; and the earth, with its horizon and meridian, 

 turn round from west, by south, to east ; and bring the 

 same points of the horizon to the sun and moon, to 

 which these bodies came when the earth kept at rest, 

 and they were carried round it ; shewing that they rise 

 and set in the same points of the horizon, and at the 

 same times in the hour-circle, whether the motion be in 

 the earth or in the heaven. If the earthly globe be 

 turned, the hour-index goes round its hour-circle ; but if 

 the sphere be turned, the hour-circle goes round below 

 the index. 



And so, by this construction, the machine is equally 



