(xrtjbb — Improvements in Equatorial Telescope Mountings. 109 



mounted on two axes at right angles to one another, thus allowing 

 of universal motion. The apparatus is so mounted on telescope 

 that one of the axes (aa), which may be called its declination axis, 

 is parallel to declination axis of telescope. If, now, telescope be 

 pointed to equator, and meridian, and circle (cc) on declination of 

 axis of position-finder made to read zero, the other axis (pp), 

 which may be called its polar axis, will be parallel to polar axis of 

 equatorial. The bubble of level L is now adjusted to centre when 

 the circle (bb) on its polar axis reads zero. 



It is evident now that the Eight Ascension and Declination 

 circles of position-finder will read the same as the Eight Ascension 

 and Declination circles of telescope, at any position provided the 

 bubble be brought to centre of glass. 



To find any object, it is only necessary to set the circles of this 

 little position-finder to same readings as the Eight Ascension and 

 Declination circle of telescope itself would have to be set to, and 

 turn instrument round till bubble becomes level. 



Addition to Existing Arrangement for Slow Motion 

 in Right Ascension. — The slow motion in Eight Ascension 



JL 



Fi*. 3. 



which the writer generally applies to his instrumeuts has often 

 been described. It consists (fig. 3) of a pair of differential wheels 

 {eld') fixed on the adjoining ends of a pair of shafts (SS) in line 



