30 J. Watcrhousc — An Account of the Tidal [No. 1, 



level of low- water neaps ; to this was attached a box containing a copper 

 float, and to the float was attached a deal rod with a pointer at the end o£ 

 it about 6i feet above the float. In the bottom of the box a pipe, two feet 

 long, of small diameter was fixed so as to permit the sea to have access to 

 the float ; the box itself was about 6 inches square and 6 feet high, the 

 side of it attached to the pile was extended upwards for 6 feet and had a 

 groove in it in which the upright rod with the index worked {vide figure), 

 so that by having this upper part numbered from a certain zero, the level of 

 the sea below this zero could be at once read off. It was found by careful 

 trial in a bucket of water that the pointer always recorded 6 feet 2 inches 

 above the level of the water in which the float worked — the scale was made 

 accordingly ; levels were taken to connect the temporary tide-gauge with the 

 top of the cylinder, for comparison of level of water inside and outside. 



It will be unnecessary to enter into details of the operations at each 

 station as they were similar to those at Okha, of which the principal out- 

 lines have been given. Full details will be found in Caj^t. Baird's re- 

 port appended to the General Eeports of the Great Trigonometrical Survey 

 for 1873-74 and 1874-75. 



Commencement and Progress of the Observations. — The regular tidal 

 registrations were commenced at Okha by the end of December 1873 ; at 

 Hanstal by the end of March 1874, and at Nawanar by the end of April. 

 It was hoped that they might have been carried on continuously for at 

 least a year, or perhaps longer, at each station, in order to furnish the re- 

 quisite data for investigations of the separate influence of each as well as 

 the combined of all the principal tidal constituents, and the least that is 

 needed for this purpose is a series of observations extending over a year. 

 During this time the errors of the clocks for driving the barrels of i-he self- 

 registering instruments would have to be frequently determined and the 

 clocks corrected ; the instruments would also have to be examined and 

 cleaned, and possibly repaired also, and the relations between the curves on 

 the diagrams and their zero lines would have to be carefully re-determined 

 from time to time ; and all this would have to be done either by Capt. 

 Baird or by his assistant Mr. Eendell. 



Capt. Baird accordingly drew up a programme for the periodic in- 

 pection of the stations and arranged that he and Mr. Eendell should make 

 tours of inspection in turn. It was calculated that a tour embracing all 

 three stations, would take about a month from the date of leaving to that 

 of returning to recess quarters ; these had been established in Eajkote, the 

 nearest town to the Gulf where house accommodation suitable for Europeans 

 could be obtained. Anticipating that during the monsoon months the wea- 

 ther at the tidal stations might be found too cloudy to permit of astrono- 

 mical observations for determining the clock errors, Capt. Baird provided 



