178 PROCEEDINGS OF SECTION A. 
late Mr. G. R. Smalley. The work then done was, however, 
abandoned in consequence of an abnormal rise in the lake by 
which the line was covered in parts to a depth of 2 feet 6 
inches, and in 1870 a new site, close to the former, was chosen by 
the Surveyor-General, Mr. P. F. Adams, under whose supervision 
the base was measured by Mr. A. C. Betts, work being commenced 
on 31st October of that year. <A report of the mode of measure- 
ment, with remarks as to the comparisons of the standard bar 
with the wooden bars actually used on the base, will be found in 
a return to Parliament, 3lst May, 1871. The standard bar is the 
O.1.,, referred to at page 175 of Colonel Clarke’s work on the 
comparison of standards, published in 1866. The difference 
between the lengths of the base as found from the measurement 
and re-measurement was ‘542 of an inch in the total length of five 
and a half miles. 
The extension of the triangulation from the base was cominenced 
in 1876, in the beginning of which year Mr. W. J. Conder ob- 
served the angles at the south end of the base ; observations of 
angles at the “other stations shown on the accompanying map 
(marked A) being made principally by the last named observer 
and by Mr. J. Brooks at various dates, as the exigencies of the 
service permitted. 
The base line of verification at Richmond, shown on the map, 
was measured by Mr. Conder in 1879-80, anda description of the 
measurement, first with the wooden bars with which the length 
of the Lake George base had been ascertained, and afterwards 
with steel bars, will be found as an appendix to the annual report 
of the Department of Lands for 1880. From this the following 
details have been extracted. The standard bar, which was the 
same as that used in 1870, is of cast-iron, about 10 feet long, 
carrying microscopally fine spots near its extremities, and supplied 
with thermometers to record the thermal state of the metal, 
mechanical contrivances to prevent sag or distortion of the bar, 
from unevenness in its supports, and with micrometer microscopes 
for viewing the spots. The standard was received many years 
ago from the Board of Ordnance in England, with its length 
determined at standard temperature of 62° Fahr., and the co- 
efficient of expansion as deduced from observations made with 
the Imperial standard yard. The straight line joining the terminal 
points of the base, which are about 7 miles apart, and are very 
fine dots in small silver discs let into copper plugs in large stones 
embedded in massive concrete foundations, was measured with 
three rods or bars so nearly equal in length to the standard that 
their difference could be determined with the micrometer micro- 
scopes with great precision. The rods in use were of two kinds— 
wood for the first measure, and steel for the re-measurement. 
They were both used with the same apparatus, which may be 
