510 Trans. Acad. Sci. of St. Louis. 
On November 18th, at the suggestion of Professor Pritchett, 
four stars were observed for determining the difference of 
personal equation by a different method. Using the St. Louis 
transit a star was observed across the first three lines of the 
reticule by observer P. and over the last three lines by observer 
U. For another star the observers changed about, U. observ- 
ing over the first three lines and P. over the last three. 
Since the power of the eye-piece of the St. Louis transit is 
more than double that of the eye-piece on my own instru- 
ment this method is open to serious criticism. The personal 
equation may and probably does depend very largely on the 
rapidity of motion of the star in the field. However, the re- 
sults as given below for the four stars observed by this 
method are so accordant that it is to be regretted that more 
observations of this kind were not secured. 
Star. Decl. r. Us P.—U. 
¢ Pisce. +.§° 3 278.05 268.93 +08.12 
¢ Pegasi +18° 32 2.97 2 .72 0 .25 
Pisce, +6 17 49 45 49 .35 +0 .10 
33 Pise. ae Bus 18 51 .96 51.78 +0 .18 
+05.162 
These two results for personal equation seem on the whole 
to be entitled to about equal weight and their mean— 0°.148 is 
adopted as the correction to be applied to 42 for difference of 
personal equation between observers. The value of 4 4 given 
by the Last Square reduction when thus corrected for personal 
equation is 
+ 8™ 995,171 + 05.04. 
The probable error of this result is estimated, and consists 
chiefly of the uncertainty of the determination of the 
correction for personal equation. 
The longitude of the west pier in the transit room of the 
Observatory of Washington University —that is the pier of 
the 3-inch transit instrument — is 6" 0™ 49°.163 as determined 
