TRIGONOMETRICAL SURVEY OF NEW SOUTH WALES. 231 
Murray to Cape Howe, forming the boundary between the colony 
and New South W ales. U Jpon this work, Messrs. Allan and 
Black were engaged, the triangulation for this purpose being 
extended to include ‘The Pilot ” and Mount Kosciusko in New 
South Wales. The triangulation connecting the ends of the line 
having been observed, the line itself was ranged on the ground to 
the calculating bearing with the gratifying result that it reached 
the coast within 7 inches of the marked terminal, a fitting tribute 
to the skill, energy, and endurance of those in whose hands the 
work had been placed. 
SOUTH AUSTRALIA. 
The first trigonometrical survey work in South Australia was 
that commenced in 1840 by Colonel Frome, R.E., Surveyor- 
General of the province, who, in the course of the three years 
following, observed a network of triangles extending over the 
hilly country—east, south, and north of Adelaide—from En- 
counter Bay to the head of Spencer's Gulf. His base was 
measured on the Adelaide Plains, west of the city, six inde- 
pendent measurements being made; the instruments used being 
a heavy steel chain of 100 feet length, and a lighter one 66 feet 
long, with brazed rings. The adopted length of the base was 
17,462°20 feet. Only ¢ one end of it can now be identified ; but 
the brass standard then used for reference is still in a good state 
of preservation at the Surveyor-General’s Office in Adelaide. 
Observations for determination of the true meridian were made: 
at four stations, with an altazimuth of English make, by J. D. 
Potter, oyine a horizontal circle of 13 inches and a vertical 
circle of 6} inches. Latitudes were found by meridian observa- 
tions of the sun and fixed stars with the sextant, and several sets 
of lunar observations were also taken for longitude. The hori- 
zontal angles were almost all taken with 5-inch “Y” theodolites, 
reading only to minutes. Six or eight rounds of angles were 
observed (as instrumental bearings increasing towards the right 
hand) at important stations, and three rounds for subsidiary 
triangles, the vernier index being set differently for each consecu- 
tive set. Reciprocal angles of elevation and depression were also 
observed to the tops of all the stone piles which mark the 
stations, thus enabling their elevation above sea level to be 
calculated. The sides of the triangles range from about 6 to 16 
miles, and the closing error of each from 3 to 10 seconds. 
Work of a similar character was carried out from 1857 to 
1860, under the direction of Colonel Freeling, R.E., Surveyor- 
General, when, in order to fix the positions of pastoral leases in 
various localities, over 100 miles apart, several base lines were 
measured with ordinary surveying chains. Thus separate systems 
of triangulation grew from these bases, which, while securing 
