TRIGONOMETRICAL SURVEY OF NEW SOUTH WALES. 233 
circumpolar stars, many of these disagree with the calculated 
bearings by nearly a minute either way, the cause of which is 
believed to be largely due to an imperfect motion of the telescope 
in the vertical plane, although precaution is taken to reverse the 
alidade of the “ Y ” theodolite at each observation, and to change 
the pivot ends of the cross axis of the telescope every alternate 
observation made with the transit theodolite. 
For the purposes of calculation the angles of every triangle 
have been made to sum 180° plus their spherical excess by 
adopting the arithmetical mean of the best observed values, and 
solved as plane triangles. Only in special cases has the method 
of “least squares ” been applied. 
The greater part of the triangulation has been co-ordinated in 
portions for plotting purposes upon different planes, the meridians 
for which are connected with initial meridian of the Adelaide 
observatory ; and a wide circuit of geodetic latitude, azimuth, and 
longitude has been computed from these, Clarke’s elements of the 
spheroid being used for the purpose. 
In process of co-ordination it becomes evident that a polygonal 
figure of about a dozen sides, comprising a surface of 500 square 
miles or more, may be selected from any part of the more recent 
work, of which the angles, if mathematically treated, will not be 
found more than 5 seconds in error. 
The trigonometrical survey of South Australia now embraces 
about 175,000 square miles, having its greatest length in latitude 
27°, stretching from the boundary of New South Wales to that 
of Western Australia, 740 miles, and between the parallels of 
latitude 36° and 26°, 688 miles upon the meridian of 139° east 
longitude. 
Particulars of Base Lines. 
Locality. Length in feet. Date. 
Oni therAdel ade WAM: se..c.Gra sec wovasecameeaees 17462:20 1840 
INGarg Mites Ser eir...canhecitaahesscuecedandaomoamiaed 10560°00 1857 
INBB got OrteAMeSta), sup ssidemasirttnssiewiasasce 23189°70 1859 
INGE Olp Make SOTLEMS) secs ei cioio wes seresemierne eicieereee 105861°90 1860 
INGA trae Na AMD) 9.) .orc:aersleesseiemtoliofioiionlaewien 58423 °20 1860 
HasternyP anya rmen tecacmereasmesuaoen cacsennocear 42461°76 1862 
HOO mn, Naf Adelaide s.icaccdeswewctesancseooes 9107°71 1880 
From the above short account, which has been forwarded by 
Mr. W. Strawbridge, the present Surveyor-General of that colony, 
for the purposes of this paper, it will be seen that South Australia 
possesses a survey, the character of which speaks well for those in 
whose charge it has been placed. Though not, perhaps, carried out 
