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3, the pencil being held above the paper by a flat spring 

 placed underneath. 



The lever (b) is supported on the horizontal post (e), fig. 

 1 ; g is a set screw for clamping to any part of the post (e); 

 h and i are weights for counterpoising the lever in any 

 position. 



The supporting axis of b is seen in fig 4, where m, m, are 

 two screws having conical points. By this arrangement, 

 we avoid all loss of motion, and have but very little friction. 



In fig. 1, k is an electro-magnet operating the arm {d), at 

 the end of which, and parallel to the axis of the cylinder, is 

 attached the cross piece j. 



The dials seen in fig. 1 indicate minutes and seconds. 



Now, when the Telescope is moved in zenith distance, 

 motion is given to the pencil so that it moves over the 

 cylinder in the direction of its axis. Whenever we wish 

 to make a record, a key is pressed which closes the circuit 

 through the electro-magnet, and a blow is struck on the 

 pencil arm, so that a small dot is made on the sheet of 

 paper covering the cylinder. 



As fast as the stars enter the field of the Telescope, they 

 are brought to the intersection of a horizontal and vertical 

 wire, when, the circuit being closed, the record is made. In 

 this way, the position of the stars in the heavens are trans- 

 ferred to the surface of the cylinder, so that when our 

 observations are finished, we have a perfect " fac simile " 

 copy of the zone of stars observed. 



With this apparatus, we have the first accurate record of 

 Right Ascension and Declination made at the same time, by 

 mechanical means. When the dot is made on the cylinder, 

 a record is also made on the working Chronograph, which 

 gives us the time to the hundredth part of a second. For 

 the exact declination, an assistant reads the Declinometer 

 scale to the five-tenths of a second. 



Therefore, when our zone is observed, we have not only 



