'The Transactions of the Bombay Geographical Society. From December 1854 to March 1856. (New Issue.) Edited by the Secretary. Volume XII.' [‎20] (39/258)

XX
PROCEEDINGS OF THE SOCfETY.
tion, on the water and earthy matter cried ont to sea annually from the shores
of North Western India, with charts and sections. , . „ a. ,
On the ordinary instruments employed and method, pursued Geograph, o,l
enquiry, illustrated by the exhibition of Instrument,. Telescope and other Op
cal inamtments,-Angle measuring instrument,,-Level,-the Barem ter T er.
mometer, Hygrometer, and Rain Gauge-Current measuring instrument,-Instru-
meats for obtaining specimen, of water from great depths,-mode of construct,ng
LSLril"-s”r’Curfo Chrommetrical Snr^,. ly Captain
.Selby, of the Shores off Bombay, betwixt Kattiawar and Vingorla,from
100 to 150 miles out from Shore. By the Secretary.
The earliest outline we have of Bombay Harbour is that contained in the work
of Freer 1681, published in the year 1697, and it seems here worthy of re-
publication, as indicative of the conceptions entertained by the earlier visitors of
the form of the island. The first really correct chart or map we possess of our
Harbour is that surveyed by Captains Cogan and Haines, in the year 1829, and
published in 1833. But their surveys only extended some ten miles out ; and we
no actual had survey of our shores out to deep water until within these past two
^ Bombay is universally famed as a harbour fit for any amount of shipping j it not
only contains safe anchorage, accessible at all seasons, for ten thousand sail
of the line, but it may be approached from seaward with the most perfect confi
dence and safety without astronomical observation, and by the use of the log and
lead alone. It will be seen from the following drawings that from 100 to 150 miles
from the shore, with which it is nearly parallel, there is a vast step or precipice,
a submarine Ghaut, of 2000 feet, which suddenly brings the lead from 50 fathoms
water to 300 fms. and no bottom : and though so long as he has 170 fathoms water
the mariner may feel in perfect security that the land is at least 100 miles away from
him, when he suddenly shcals to 50 or 60 fathoms or so, then he may, by the gra
dual sloping and well defined character and frequent changes of the components of
the bank, which fronts the coast of the Konkan from Rutnagherri to Deo, and tails
away out from Bombay Harbour, almost track his path by the unaided lead to with
in sight of the Ghauts or Lighthouse without having seen for days either sun,
moon, or star: a peculiarly well marked shoal of about 20 fathoms water 40 miles
south'of Bombay 30 off the coast of It aj pore bearing the name of “ Direction Bank”
on the charts and sailing directions. These facts will be made clear from the two
reduced Charts at the end of the Number: as they are not intended for nan*
tical purposes, nearly the whole of Lieutenant Selby’s figures have been omitted
four lines of sectional soundings Measurements of the depth of a body of water. , at right angles to the shore, corresponding to the
sections in Chart II., and three at right angles to these, sufficing for our purpose.
The following curious facts, which the accompanying diagram will better
explain, are brought to light;—There must have been a time, by no means