eames er ee 
LONGITUDE OF THE SYDNEY OBSERVATORY. 67 
The value S—e in the eighth column of the table is the difference 
between the calculated apparent semi-diameter (S) of the moon 
and the caleu rane = comm distance (c) of the star from the 
moon's centre for the Observatory mean solar time of disappear- 
10h. 38m. 23°34s. 
It may also be well to state that the observation of the dis- 
pearance of y Aquarii on November 30, 1870, was 
It wi 
for longitude is 10h. 3m. 21°58s. E., which agrees pretty well 
with that derived from the occultations. In May, 1865, a number 
of signals by electric telegraph were ren a between the late 
myself, in order to det the difference of 
longitude between Sydney and Wind sor. “The result of this 
exchang ignals was that my observatory was lm. 30°04s. 
west of that of Sydney. No regard, however, was paid to per- 
sonal equation in this determination. If now we add this quan- 
tity to the corrected longitude of my observatory, as given in 
this paper, we have 10h. 4m. 53°38s. E. as the longitude of the 
Sydney Observatory. This value is Fm by 7° ‘64s. than that 
determined by the Rev. Mr. Scott from moon-culminations at 
g 
oe 
® 
meri rv. 
made at all the principal observatories roe se the semi-lunations 
in which the occultations have occurred. 
