"معاملات الجمعية الجغرافية في بومباي. من يناير ١٨٦٣ حتى ديسمبر ١٨٦٤. (تحرير السكرتير.) المجلد XVII." [‎١‎٦] (٥٢٤/٤٥)

proceedings of the
. x 41
formula for calculating the time of high-water and hourly changes of the
tides at this port, than those commonly used by the navigator, or that
given by Professor Orlebar.
Mr. Burgess replied, that lie perfectly understood that the business,
of the Observatory officially was to chronicle the observations; ii 0r
did he think he had intentionally given occasion in his paper to
Lieutenant Fergusson to suppose that he was so' unacquainted with
ks duties as to expect more. In attributing the formula hitherto
employed at Colaba for computing the times of high-water for the
Bombay Almanacs to Commander Montriou, he had apparently
been misled, by the circumstances, that Commander Montriou’s name
alone appears on the title page of the second pait of the Ooservations
for 1847, and that no mention is made in the discussion of the
tidal observations there collected of Professor Orlebar’s name. He was
perfectly aware of the method used by seamen for all ports of ap
plying a Constant to the time of high-water at London Bridge, in
order to obtain approximately the time at any other porthut Lieu
tenant Eergusson must be as well aware as he was, that if this
method were a correct one, there w r ould he no sufficient cause for
continuing the observations at Bombay or anywhere else longer than
Was necessary for the determination of the time Constant or the
cc establishment of the Port.” But the assumption was erroneous. The
tide at London is of a peculiar character, arising from the confluence
of two tidal waves passing round the southern and northern extremities
of the island, and being of different ages when they arrive at the mouth
of the Thames, the London tides are of an unusual character. Again,
the age of the tide at London was upwards of tw r o days, so that for
Bombay, where the tide cannot he much more than one day old,
we ought to subtract a constant quantity, not from the time of the
fiist, but from that of the 2nd or 3rd following tide at London, in order
to obiaxn the time of the local high-water approximately ; for it is
well known, that the interval between the moon’s southing and high-
water depends mainly upon, the age of the tide. He thought there
was came therefore for instituting the observations and for continuing
cm, until we had independent means, founded on their results, for
e ermmmg the tidal phenomena, without reference to the Nautical
lac method, which was never meant for anything hut a rough
P! ximation to sene in want ot abetter; and in employing the