Ard À 
Although these calculations are inaccurate owing also to the fact that 
the intervals between the time determinations often differ rather much 
from 6 days, yet it is evident that the M. E. 3 are much larger 
than the M. E. @ and hence that considerable perturbations of long 
period exist, as, indeed, a glance at the table of the obs.—comp. 
also shows. It would be possible to account tolerably well for the 
values found for the three different mean errors by assuming, quite 
arbitrarily of course, that there are two kinds of perturbations, one 
constant during 6 days and another consiant during a month. We 
should then have to assign for the whole period an average value 
to both of + 05.02 and for 1901—1902 alone one of + 05.015. 
There are not many clocks about which investigations have been 
published, which allow us directly to compare the regularity of 
their rates with that of Honwt 17 and most of these embrace but a 
short period. 
An investigation extended over 4 years about the standard-clock of 
the observatory at Leipzig Drenckrr 12 has been published by Dr. 
R. SCHUMANN '). He uses 224 time determinations at mean intervals 
of 6'/, days and derives for the rate a formula containing a linear 
influence of the temperature and of the barometric pressure and besides 
a term varying with the time elapsed since a zero-epoch. As mean 
value of the difference obs.—comp. he finds + 0%.059 and there is 
no evidence of a residual yearly inequality. I calculated also the 
mean value of a difference between two consecutive rates and 
found 450.055: 
In the latter respect we possess also data about the four normal 
clocks of the Geodetic Institute at Potsdam. An investigation by 
Mr. WaracH ®), about the rates during last year gave the following 
mean differences between consecutive rates after correction for the 
barometric pressure, while the temperature was kept very nearly 
constant: 
STRASSER 95 = O8.054 
RiEFLER 20 + 0.062 
DerNCKER 27 + 0.047 
DeNCKER 28 + O .049. 
These values are considerably larger than that for Honwé 17, but 
respecting the Potsdam clocks we must keep in view that DENCKER 
1) R. Scuumann. Ueber den Gang der Pendeluhr F. Dencxer XII. (Ber. Sächs. 
Gesellsch. d. Wiss. 1888). 
*) Jahresbericht des Direktors des Königlichen Geodätischen Instituts für die Zeit 
von April 190L bis April 1902, pg. 35. 
