102 BULLETIN OF THE UNIVERSITY OF WISCONSIN 



From the equations 



AT+ 1M Aq> = 18.56 v = +0.02 



AT-Z.\\A(f> = 24.33 + .20 



AT- 1.41 Aq> = 22.87 - .17 



jr+1. 95 ^<p = 17.80 - .04 



we obtain 



. s. 

 JT = + 20.86 2f(? = - 1.55 = - 23.3 



with the residuals placed opposite the several equations. 



In the above reduction the computations have been car- 

 ried to tenths of a second of arc and hundredths of a 

 second of time, but it is evident that quantities of this order 

 are imperceptible in so small an instrument, a second of 

 arc being approximately the limit of what can be seen in 

 its telescope or measured by its level. The internal agree- 

 ment of the observations as shown by the residuals is, 

 therefore, satisfactory, and the absolute values of the lat- 

 itude and clock correction furnished by the observations 

 are also in excellent agreement with the data furnished by 

 a geodetic connection with the "VVashburn Observatory and 

 a comparison of the chronometer with the normal clock. 

 Thus after correcting AT for diurnal aberration we have 



s. ' 



From Observation AT = + 20.88 q> = 43 4 36.7 



From Comparisons = +20.80 = 43 4 36.5 



This excellent agreement is due, at least in part, to the 

 reversal of the instrument, one-half of the observations 

 having been made Circle Right and one-half Circle Left, 

 thus eliminating the effect of error in the assumed thread 

 intervals. 



In order to secure the convenient observation of stars it 

 will be advantageous to prepare in advance an observing 

 programme showing the time at which the several clock 

 stars cross the almucantar of the polar star, and their cor- 

 responding azimuths. If only a few stars are to be in- 

 cluded in the programme this can be most conveniently 

 done by putting T 2 = T^ in equations (13) and solving with 



