Magnetic Observatory, Hobart Town. 267 
than the former; but I have not been able to ascertain the 
amount of their power. 
The lunar observations were made with an excellent 
sextant, by Dolland, of 8 inches radius, divided on platina, 
to 10". I am not able at present to communicate the 
resulting longitude, as they will shortly be in the hands of 
Mr. Riddle, the Head Mathematical Master of the Nautical 
School at Greenwich, for calculation by the first-class boys 
at that school, under his superintendence. ‘The results will 
be communicated hereafter. 
The determination of the latitude of any place is a much 
simpler problem, and for the present all the latitudes given 
in this paper have been the result of observations made 
with the above-mentioned sextant by the method of circum- 
meridional altitudes of the Sun and Stars. In their reduction 
I have employed Mr. Baily’s Tables and Formule of re- 
duction to the meridian, and Mr. Ivory’s Tables of Refraction, 
with their corrections for pressure and temperature. 
The Sun's declination was obtained by interpolating for 
second differences, and the Stars which have been employed 
being ‘‘ Greenwich Stars,” their declinations were obtained 
from the Nautical Almanac. 
Should I remain at the Observatory through the ensuing 
winter, I propose to investigate the latitude in a more 
rigorous manner, by the employment of the Altitude and 
Azimuth Instrument by Troughton, with which Mr, 
Sprent conducts his field operations in the Trigonometrical 
Survey during the summer months, and for which permis- 
sion I am indebted to His Excellency the Lieutenant- 
Governor; but from the numerous observations made at 
various times with the sextant, I do not think that the 
latitude assigned to the Observatory can be much in error, 
although future observations, with better means than I have 
Y2 
