186 Captain Sabine’s experiments to determine the 
by a theodolite, the telescope of which being placed on a 
level with the pendulums, and adjusted horizontally, the height 
on the ship’s mast cut by the middle wire was carefully noted : 
this height was thirty-four feet six inches above the low 
water mark on a graduated tide pole, which was moored to 
the bottom near the ship. The measurement was repeated 
with the magnetic transit instrument, and gave precisely the 
same result. The distance between the station and the ship 
being about seven hundred yards, the true height may be 
considered thirty-four feet, the six inches being omitted in 
compensation of the distance. The corrections due to this 
elevation are for clock 1, +o, 1413, and for clock 2, +0,1415, 
making the final results 86466,4793 and 86571,858 vibra- 
tions in a mean solar day, in vacuo, at the level of the sea ; 
the temperature being 45 0 . 
It has been noticed, that previous to the embarkation of the 
clocks on the voyage, they had gone for a few days in Lon- 
don with the pendulums interchanged, with a view to ascer- 
tain the comparative influence of the maintaining power of 
the clocks, on the number of vibrations made by each 
pendulum. 
The preceding observations having been concluded at Mel- 
ville Island on the 14th of July, at which time there appeared 
no immediate prospect of putting to sea as no water was yet 
visible, a second series was commenced with the pendulums 
placed in the clocks marked differently from themselves ; 
the ships did not quit the harbour until the 1st of August, 
which afforded sufficient time for the completion of this series 
also ; and thus four results were obtained, instead of two, 
towards the deduction of the acceleration of the pendulum 
at Melville Island. 
