'The Transactions of the Bombay Geographical Society. From January 1863 to December 1864. (Edited by the Secretary.) Volume XVII.' [‎8] (169/524)

8
BOMBAY TIDAL OBSERVATIONS FOR 1861.
unfairly balanced—-the positive against the negative ; and if this be not an
accidental result, the first supposition is excluded, and we must infe”
that the differences are partly, if not mainly, owing to the insufficiency
of the formula to represent the phenomena. To prove this, a more ex
tensive investigation of the observations of other years would be require,}
It may be tested, however, to some extent by a graphical construction!
I accordingly laid down the whole 335 tides of the upper transit, both
as computed and observed in reference to the times of nearest transits,—
and an examination of this projection Any method by which the earth’s curved surface may be transposed (or projected) on to a flat surface. showed that, whilst for continued
periods the observations followed continuous curve lines, there were also
breaks in the continuity that seem only explicable on the supposition of
considerable observational errors. Independently of these exceptional
instances however, a large number of observed lines lie quite beyond
the limits assigned by formula to any tide throughout the year.
In conclusion then, it seems evident that the tables and formula of
Professor Orlebar are not sufficient for the prediction of the tides at
this port. Indeed, he himself never intended that they should be used
longer than until 9 or 10 years’ observations had been collected, and a
fuller investigation could be entered upon. During the course of
16 years, such observations have now been accumulating at the
expense of Government, and if, in respect to this matter, Bombay
would stand in creditable comparison with other commercial cities,
we must have a fresh investigation of the tides based on these
observations. Sufficient materials have been ready for the last six
years. Of the importance to public interest of a thorough discussion
of them for the production of correct tide-tables for this harbour,
there are Members in this Society better able to judge than I am. I
have to regret that want of leisure has prevented my making this
examination more extensive and more fruitful in definite results,—an
examination of the heights of the tides might have confirmed the
results derived from the intervals, and developed other particulars which
I had attempted to elicit by calculation, but had not time to verify.