AT THE OBSERVATORY AT PARAMATTA. 
29 
From the known right ascensions of the Moon’s culminating Stars, observed 
on the given day, I deduce the true right ascension of the Moon’s centre for 
the apparent time of the Moon’s limbs passing the middle wire. For the cor- 
responding time at Greenwich (found here upon the supposition of the longi- 
tude = 10 h 4 m 3 s ), I find also from the Nautical Almanac, the Moon’s right 
ascension, applying thereto the correction found from the Observations made 
on that day at Greenwich. The difference between the two right ascensions, 
divided by the Moon’s horary motion, which need only to be known superficially, 
is the error of the assumed Longitude, which in East Longitude is additive or 
subtractive, accordingly as the Nautical Almanac gives the Moon’s iR greater 
or less than the Observation. 
The above Longitudes rest merely upon a comparison with the Nautical 
Almanac. When the errors thereof are once known, it will be sufficient to 
apply double their quantities to the Longitudes in time found on the corre- 
sponding days. 
The Longitude of the Observatory by a mean of all hitherto calculated 
Observations, including the occultations, is 10 h 4 m 6 S .25. 
Port Jackson. 
The geographical position of Port Jackson being of nautical importance, I 
think its determination here is not misplaced. 
The observations of Sir Thomas Brisbane with two reflecting circles of 
Troughton and one of Jecker, give the latitude of Government House at 
Sydney 33° 51' 58" S. 
Sir Thomas Brisbane observed the eclipse of the sun 16th August 1822, at 
the same place, as follows : 
h m s 
E?d nnins : : : 
Hence I find by a comparison with the Nautical Almanac the h m 
longitude of Sydney 10 5 17-89 
The solar eclipse of 9th December 1806, observed by Admiral 
Bligh, gives, according to my calculation, 
Another, observed by Captain Philip Parker King, R.N. . . . 
By chronometers frequently carried backward and forward between Pa- 
