Section E. 
1.—DETERMINATION OF THE FORCE OF GRAVITY 
AT MELBOURNE IN AN ABSOLUTE MANNER 
(1863) AND SUBSEQUENTLY ALSO RELATIVELY. 
By Dr. Neumayer, Foreign Member of the Royal Society, 
London. 
DESCRIPTION OF THE APPARATUS. 
As far back as March, 1859, I had resolved upon entering 
into a series of observations with a view to determine the length 
of the pendulum vibrating seconds at Melbourne, and an ap- 
paratus for this purpose was ordered from Europe. My friend, 
the late Prof. Peters, of the Observatory at Altona, who has 
been engaged in pendulum observations under * Schumacher,” 
kindly undertook to superintend the construction of a reversion 
pendulum, with the execution of which task W. F. Lohmeier, 
of Hamburg, had been entrusted. For certain reasons the work 
proceeded only slowly, and it was not until June, 1862, that 
the apparatus arrived in the colony; this delay, however, 
matters but little, as the buildings of the Flagstaff Observatory 
were altogether unsuitable for measurements of so delicate a 
nature, and no other buildings were at my command. I deter- 
mined, therefore, to defer the pendulum observations until 
after the removal of the Magnetic Observatory to the new 
buildings, and until the arrangements for the new Astronomical 
Observatory had been completed. The selection of a locality 
was a task of considerable difficulty, as particular attention had 
to be paid to the fact that no local irregularities in the geo- 
logical formation should impair the value of the observations. 
I was, however, greatly assisted in this matter by the extensive 
labours I had undertaken in the winter of 1860 round Mel- 
bourne, with a view to determine the locality most suitable for 
an observatory for the advancement of physical science. By 
these labours the fact had been clearly established that such an 
institution should not be erected towards the west of the 
meridian passing through the Melbourne University, and that 
the locality where the new observatory now stands was in 
every respect most favourably situated for all purposes. 
The houses, which subsequently to the removal of the observa- 
tory were occupied by the officers of the magnetic survey, pre- 
sented an excellent opportunity for carrying out the long- 
