ASTRONOMICAL INSTRUMENTS. 

 Fig-. 131. 



the whole of the upper works, and also a pointer, to show 

 the degree and nearest five minutes to be read off on the 

 azimuth circle ; the remaining minutes and seconds being 

 obtained by means of the two reading microscopes, F and 

 G ; this plate, by means of the conical part, B, which is 

 carefully fitted to the axis, rests on the axis, and moves con- 

 centrically with it. The conical pillars, H H, support the 

 horizontal or transit axis, I, which being longer than the 

 distance between the centre of the pillars, the projecting 

 pieces, c c, fixed to their top, are required to carry out the 

 Y's, a a, to the proper distance for the reception of the 

 pivots of the axis ; the Y's are capable of being raised or 



