282 Geographical Position of the 
As Fort Mulgrave, in Suilivan’s Cove, is the spot where 
ships resorting to the Port of Hobart Town usually take 
their observations for rating their chronometers and ob- 
taining their error upon Greenwich mean time, it may be 
of service to assign to it a correct geographical position, 
obtained from the foregoing determination of the Obser- 
vatory. 
Employing the royal salute fired at the Prince of Wales’s 
Battery, (Fort Mulgrave), in 1846, for the measurement of 
a base line, I ascertain the Observatory to bear from Fort 
Mulgrave N. 11° W. 7300 feet, which, with an assumed 
sas LVR nas a Fed 
Sumas 304 SYS ]- 18° diff. of latitude. 
S. 
* 0" 18° (or 1:20) diff. of longitude 
between them. 
This would place Fort Mulgrave in 
° ' " 
42° 53: 32° South latitude. 
hs, amis: 
9° 49° 29°6 
ae ry East longitude. 
Ae 224 
Before concluding this paper I think it very desirable 
to furnish the result of data, which I have been able to 
collect, for the determination of the longitude of Fort 
Macquarie, in Sydney Harbour, which, as the centre of 
a vastly increasing trade, and the resort of hundreds of 
vessels, is daily becoming of more importance. As before 
meridional altitudes at the upper transit are too great, and ‘ sub polo,’ their 
altitudes are so low, that it is only on rare and chosen occasions of an 
unusually clear atmosphere that satisfactory observations can be obtained. 
The true meridional altitude of B Centauri ‘sub polo’ is only 12° 31’°.— 
Achernar and Canopus, which are both brilliant stars, are too low, being 
respectively only 10° 50’ and 5° 29’. 
