26 J. Waterbouse — An Account of the Tidal [No. 1, 



V. — An Account of the Tidal Observations in the Gulf of Cutch, conducted 

 by the Great Trigonometrical Survey, under the Superintendence of 

 Colonel J. T. Walker, C. B., R. E., during the years 1873-74-75. 

 Corn-piled from the G. T. Survey Reports by Captain J. Water- 

 house, Assistant Surveyor General. 



Origin and Object of the Observations, — In his Report on the Operations 

 of the Great Trigonometrical Survey for 186G-67, Col. Walker writes : 



" Dr. Oldham, the Superintendent of the Geological Survey of India, 

 has recently drawn the attention of the Government to certain questions 

 which have been raised regarding secular changes in the relative level of 

 the land and sea, which are believed to be going on in various parts of the 

 Bombay Presidency, and more particularly at the head of the Gulf which 

 separates the province of Cutch from that of Kattywar. Dr. Oldham 

 recommends that certain points should be selected on the south coast of 

 Kattywar, and as far up the Gulf as possible, and that the existing relative 

 levels of land and sea should be determined at those points by accurate tidal 

 observations carried over as long a period as possible, the tidal stations be- 

 ing connected by lines of levels. Thus, by repeating the operations at a 

 time sufficiently distant to allow the secular changes to reach an appreciable 

 magnitude, this question, which is of much scientific importance, will be 

 satisfactorily settled." 



The Government of India sanctioned the observations being made, and 

 Col. Walker was making arrangements for carrying them out, when a very 

 considerable reduction in the expenditure of the Survey Department, in 

 consequence of the financial difficulties in 1869-70, caused the indefinite 

 postponement of the operations. It was not until August 1872 that steps 

 could be taken for commencing them. 



The delay which thus took place is, however, not to be regretted, be- 

 cause it resulted in the investigations being carried on in a more complete 

 and elaborate manner than had been originally contemplated, with a view to 

 acquiring more comprehensive and accurate results than were at first 

 desired. 



Happening to be present at the Meeting (in Edinburgh) of the British 

 Association in 1871, Colonel Walker ascertained that a Committee of the 

 Association, presided over by Sir William Thomson, had initiated a system 

 of tidal investigations which was anticipated to secure scientific results of 

 the highest value. On studying the details of these operations he found 

 that his original programme, which contemplated tidal observations of only 

 a few weeks' duration, would be inadequate to detect the existence of minute 



