Hi M MIKS. If the instrument is not in a very stable condition it will be best to 

 re-set on 0, point at the azimuth mark amiin. ami ihcn re-set at the proper altitude as 

 nearly as possible, before making the second observation. 



The nearer the sun is to the east and west points the better the result. Observa- 

 tions near noon should be avoided. Observations at very low altitudes, say under 10 

 are unsatisfactory. 



If only approximate results are desired the vertical wire may be made to bisect the 

 sun's disc in both cases. This would avoid the mistake of getting the wrong limb. 



Date, April 10. 



Forenoon observation 

 Afternoon " 



Diff. lli. = 54" 

 64" X 9. 5 h. =513" 

 cos<= .7314 

 sin t= .04<i!> 

 2 cos <f> sin t = 1.3851 



EXAMPLE. 



Latitude 43 N. 

 vernier A. Watch Keailinir. 



13 26' right of mark 7'- 18n. 



. . 148 13' " " 4h. 48m. 



mean 80 49' 30" 



diff. 9k 30m. 



t = 4h. 45m. 

 = 71 15 



mean 80 49' 30" 

 corr H' 10 



Angle between 



meridian and mark 



80 43' 20" 



Hourly Motion of the Sun in Declination. 



