424 
Transactions of the Boyal Society of South Africa. 
The last extensive series of time determinations with the old transit 
instrument, made by observing transits over fixed webs with chronograph 
and key, was made in the year 1906, and seven regular observers shared 
the work. From a discussion of the year's observations, persistent 
personal differences amounting in the extreme to as much as 0*23 s. were 
found to exist. 
In the years 1908 and 1909 six regular observers shared the transit 
work, working by the travelling wire method, with hand guiding. An 
independent discussion of each year's observations led to the following 
determinations of the personal discordances : — 
1908. 1909. 
* s. s. . 
C -0-007 -0-004 
A.P +0-014 +0-014 
E.C +0-013 +0-010 
A.W -0036 -0-035 
M +0-023 +0-026 
J.W -0-008 +0-001 
Notice here that the extreme discordances between different observers 
amounts only to 0-06 s., i.e., about a quarter only of the similar dis- 
cordance found in using the older method. The close reproduction of the 
results derived in the two years indicates, however, that, small as the 
residual phenomena are, they are real and not merely illusory results 
obtained by pressing the accuracy of the reductions to an unjustifiable 
number of decimal figures. 
Coming now to personal errors as dependent on the magnitude of the 
stars under observation, it was found from a special series of observations 
in 1906, in which five difi"erent observers took part, that between the 
range of magnitude of the bright clock stars and the faintest stars that can 
be conveniently observed, the discordances amounted at most to 0-03 s.,t 
and the reality of this quantity was by no means fully established. With 
the older method of observing, persistent discordances, over the same 
range of magnitude, of 4 or 5 times this amount are not uncommonly 
shown. 
* The initial letters refer to the following observers : — 
C. = Mr. W. H. Cox. 
A.P. = Mr. J. A. J. Pead. 
E.C. = Mr. R. W. Cheeseman. 
A.W. = Mr. A. J. Wilkin. 
M. = Mr. H. F. Mullis. 
J.J. = Mr. J. W. Jackson. 
J.W. = Mr. J. C. Wood. 
S. = Mr. F. H. Scragg. 
t Monthly Notices of E.A.S., Ixvii., p. 379. 
