Page:A Voyage of Discovery and Research in the Southern and Antarctic Regions Vol 2.djvu/62

46 The following evening being favourable for our projected experiments, Mr. Smith was despatched to an intermediate station, called Bedlam, to set-off some rockets, as we considered it probable that we should see them more distinctly than if sent up at either of the extreme stations. The instant of each rocket's explosion was noted at both places, and, after several nights' observations, the results were brought into comparison, and found to differ only in tenths of a second; twenty-five were judged sufficient for the accurate determination. The mean difference of time obtained amounted to 55$s$.85, and, taking the longitude of the observatory at Paramatta at 10$h$ 4$m$ 6$s$.25, as given in the Third Part of the Philosophical Transactions for 1829, p. 16–29., would give for the longitude of the place of observation at Garden Island 151º 15′ 31″.5 E.; and again applying the meridian distance between this place and the Ross Bank observatory, as given by the means of our chronometers, we find the longitude of the latter place from these data to be 147º 23′ 40″.7 E.

We found after a few trials that the rockets sent up at Garden Island could be seen perfectly well from the Paramatta observatory, which rendered the night excursions to Bedlam unnecessary.

Although the general magnetometrical observations were complete by the 28th July, the weather was so unfavourable that the absolute determinations could not be obtained until the 2d of August, which day was also devoted to making such