1838.] Proceedings of the Asiatic Society. 577 



Public Department. No. 1, of J838. 

 Our Governor General of India in Council. 

 Para. I. We forward to you copy of a memorandum by the Rev. W. Whewell 

 a Vice-President of the Royal Society, from which it appears that great service may 

 be rendered to science by means of tide observations upon the several coasts of the 

 East Indies, and that the knowledge thus obtained would be at the same time a 

 valuable acquisition for the purposes of hydrography and navigation. 



2. We transmit in the packet proper forms and instructions for registering the 

 tide observations, and we direct that you issue the necessary orders to the local 

 authorities in India to conduct the observations in accordance with such memoran- 

 dum and instructions, and to transmit the result periodically to us. 



We are, &c. 

 (Signed), 

 J. R. Carnac, J. L. Lushington, H. Lindsay, Jno. Masterman, Rd. 

 Jenkins, John Loch, C. Mills, John Cotton, P. Vans Agnew, J. Petty 

 Muspratt, H. Shank, John G. Ravenshaw, H. St. G. Tucker. 

 London, the 2\th January, 1838. 



Memorandum respecting Tide Observations. By the Rev. W. Whewell, Cambridge. 



A great service might be rendered to science by means of Tide Observations made 

 by order of the East India Company upon coasts of their territory, and the know- 

 ledge thus obtained would be at the same time a valuable acquisition for the pur- 

 poses of hydrography and navigation. 



There are no good observations of the tides of the Indian Coasts, so far as I am 

 aware, with the exception of about a year's observations made at Singapore by or- 

 der of the directors, which turned out of extraordinary value and iuterest*. If the 

 tides were observed for a fortnight at a series of points along the coast, we should 

 be able to trace the progress of the tide. wave in those parts of the ocean, and if ob- 

 servations for a longer period were made at places where there is a marine establish- 

 ment, good tide tables might be calculated, and other important theoretical and 

 practical results obtained. 



Instructions and forms for registering such observations may be had by applica- 

 tion to the Hydrographer at the admiralty if desired. 



London, December 22nd, 1837. 



Second Memorandum. 



The tide observations which the Court of Directors has resolved on instituting 

 will not only serve the beneficial purpose of ascertaining the Tide establishments 

 along the coast of India upon a consistent basis with each other, but will also give 

 the most important assistance to those philosophers who are now engaged in the 

 investigation of the theory of the tides. 



For the former purpose it will be sufficient if for three or four months simultane- 

 ously, in as many places as may be practicable, a register be kept of the times of 

 high and low water by day and night, and of the heights as shewn upon a staff to 

 which the tides rise and fall. The only difficulty in these observations will be the 

 selection of proper places as much as possible sheltered from the external swell of 

 the sea, and to which convenient access may be had at all times for the observer. 

 And, secondly, the accuracy of the watches or clocks employed, which should be 

 duly adjusted to mean time. For the latter and higher purpose, it would be desira- 

 ble to have a tide guage constructed and if possible, upon a self-registering princi- 

 ple. The waters should be admitted only through small holes in the bottom of the 

 tube or trunk so as to resist the action of the swell, and yet so as not to be choked 

 by weeds or mud, and the tube should be fixed precisely perpendicular. The float, 

 of cork or hollow copper, should move without friction, and the rod should be so 

 varnished as to prevent any change in its specific gravity for imbibing the water. 



Any ingenious workman will find it easy to make this rod carry up and down two 

 small sliding pieces, which shall retain their maximum and minimum positions and 

 thus register the rise and fall. 



In fixing this machine it will be of little consequence where the nominal zero is 

 placed, provided its precise level is referred to some known and permanent point on 

 the shore, with which subsequent observations can be compared. The heights how- 

 ever are of secondary importance, the principal object required being the exact 

 periods or times of high and low water, and therefore great attention should be paid 

 to ascertaining the rate of the clock or watch, for which purpose a small transit in. 



* These ar« printed in the As. Res. vol xix. 



