Art. IX. Description of a Mew Machine for Cataloguing and 

 Charting Stars, by G. W. Hough, A. M. 



[Read before the Albany Institute, January 13, 1863.] 



The progress of Instrumental Astronomy has been so 

 rapid during the last half century, not only in the perfect- 

 ing of the older instruments, but also in the invention of 

 new methods of observation, that at the present time more 

 can be accomplished in one year than could formerly have 

 been done in two. 



In the year 1848, the application of Electricity to the 

 recording of Astronomical Observations was first suggested. 

 This happily conceived idea soon resulted in the construc- 

 tion of Chronographs by various persons, by which the 

 instant of transit of a star was accurately recorded in a 

 legible and permanent manner. Success in the recording 

 of one ordinate of a star's position would naturally suggest 

 the possibility of fixing the other by the same agency. 

 But with the exception of some experiments made by the 

 late Prof. 0. M. Mitchel for the recording of declinations 

 by electricity, this subject, so far as I know, has not been 

 undertaken by any other astronomer. 



In the formation of catalogues of zone stars, astronomers 

 have almost invariably used the Telescope in a fixed posi- 

 tion, and, by means of a diaphragm or scale placed in the 

 focus, determined the time of transit and difference of 

 declination. In our method, the Telescope is moved in 

 zenith distance, the amount of motion giving us the differ- 

 ence of declination. 



This method of observing the difference of declination 

 between two objects, by magnifying by mechanical means 

 the angular motion of the Telescope, is due to the late 

 Prof. 0. M. Mitchel, who first put it in practical operation 

 in the year 1849 ; the apparatus used for this purpose 



