Turn the main telescope downward and locate the meridian on 

 a stake without disturbing the position of the Solar. Bring the 

 main telescope back to a horizontal position and clamp. This 

 secures a truly vertical position for the polar axis. 



Turn the solar telescope downward and fix a stake in any con- 

 venient place as indicated by the central vertical wire. The angle 

 subtended at the instrument between these two stakes is the sun's 

 right ascension, or hour angle, for the instant of observation. Meas- 

 ure as accurately as the graduation of the instrument will permit 

 and reduce the angle read to time, remembering that 15 = lh; 

 1 = 4 min.; 15' = 1 min., and 1' = 4 sec. 



Example 



Observed Azimuth 49 38' 30" 



3 hours . .. 45 



16 min. 



4 38' 30" 

 4 



2 min. 



30 sec 

 4 sec 



3 h. 18 min. 34 sec. 



.s>< l\it>i? P .V.\7//, .\j>prndi.r. taken front (,'tnl. l.tind\Offict l-'ield Manual 



Sun's Parallaxlin Altitude 



172 



