302 W. A. Rogers on Variability of Personal Equation. 
IV. Error of centering a single star, —=-'02 (estimated). 
V. Error arising from the condition that the re- 
volving pins may not have been ina verti- 
cal plane with the stationary ones at the 
instant of conjunction, ==+'005 (estimated). 
VI. Parallactic error, arising from the par- Inappreciable, the re- 
-allax of the two wires at the instant volving wires almost 
of observation. touching the fixed one 
be accounted for either as instrumental errors, or as errors 
observation, but must be due to the external conditions under 
which the observations were made. Having determined the 
—— of the general variability of the personal equation, Jet us 
3 = 'w consider the variations due to certain given physi . 
L Does the personal equation vary between a normal and an ab- 
: normal position of’ the body during observation ? 
So Normal Position minus Abnormal. 
Mean = —-0115 
