REPORTS FROM THE SECTIONS. 223 
eye and on the ear, is not the same when the moon is observed 
with the eye as when a star is observed with the eye. The evi- 
dence of this is given in the following numbers :— 
“ By observations of the first limb of the moon from 1847, May 
16, to 1848, May 28 :— 
The mean of 45 errors of moon’s tabular R.A., 
by Mr. Dunkin, is plus 0°53 secs. 
The mean of 35 errors, by Mr. Breen is...... plus 0-99 
Excess of Mr. Breen ‘plus 0-46 secs. 
“ By observations of the second limb of the moon through the 
same period :— 
The mean of 33 errors by Mr. Dunkin is ..._ plus 0:50 sees. 
The mean of 27 errors by Mr. Breen is...... plus 0°80 secs. 
Excess of Mr. Breen plus 0°30 secs.” 
—Introduction, “ Greenwich Observations, 1848,” 70. 
Here then we have a difference between observers which would 
make a difference of about 10-00 secs. of time in the longitude ; 
and a careful examination of all the moon observations at Green- 
wich by Mr. Dunkin, and published in the R. A. S. N ie vol. 
19, page 259, revealed the fact that no two of the shee rs had 
the same personality in observing the moon. sche rp 
this fact in explanation of a sug geestion T have to ake to-night on 
the cause of the difference in the ai aera of Sydney page ek 
as determined by the Rev. W. Scott and myself—a differe 
neg appeared as soon as I Asie 4g take the “taeidicun? in 
The aly of Sydney Observatory now cad was determined 
by the Rey. W. Scott from 48 observations of the moon, taken 
during 1859, 1860, and 1861, and compared with observations 
taken on the same — at Greenwich, or the Cape of Good Hope. 
vations of the moon, and, kabemey for 36 of them, correspond 
ing observations at Greenwich ; from all these the longitude 
derived was 10h. 4m. 507 "50s. During 1864 to 1870 taalire 
— Smalley did not observe for longitude. In 1871 I again 
rved, and had twenty-four corresponding observations from 
Greenwi wich, the mean of which gave 10h. 4m, 5091s. for the 
longitude of Sydney. In 1872 the paar of comparisons 
_ between Sydney and Greenwich from cloudy weather and other 
causes was only seven, giving for this year a mean longitude of 
