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Apparatus for Registering the T'ides. 



[Oct. 



V. — Suggestions for an Apparatus for Registering the Tides, — 

 By Lieutenant J. Campbell. 



TO THE EDITOR OF THE MADRAS JOURNAL, 



Dear Sir, — Mr. Prinsep in his letter to you regarding the observa. 

 tion of the height and time of arrival of the tide wave, having offered 

 no suggestion as to how the observation may be made, I therefore 

 offer the following remarks. On the east coast of the Peninsula the 

 surf every where prevents any possibility of ever guessing the time 

 and heights of high water, and in the small rivers the bar is always 

 so shallow as to prevent the influx of sufficient water, so that the head 

 of the river is always much below the surface of the sea, and the 

 current continues to run in long after the time of high water, until the 

 sea has again fallen to the level of the river. 



I believe an attempt was made sometime ago to register the tide 

 by a float in the end of an iron pipe brought in from beyond the surf, 

 but I believe it soon choaked with sand. I conceive that the 

 required observations may be made beyond the surf, by having 

 a large bamboo with the divisions bored through, set up beyond 

 the surf and supported by four ropes under water, attached to small 

 wooden anchors, the lower end may be allowed to enter six feet 

 into the sand, and a round board fastened to the bamboo will prevent 

 its sinking further. Above this board an aperture should be cut to 

 allow the water to enter and the sand to fall out, which may be thrown 

 in at top. The top of the bamboo being five feet higher than high 

 water mark, the height of the water within the bamboo may be shewn 

 by a rod attached to a cork float, and a flat wooden scale may be fixed 

 on the rod with inches painted on it, which can be read off by a teles- 

 cope from the shore. A piece of wire passing through a slit in the 

 scale will ensure its being kept parallel to the shore. 



A palmira tree might be used for the bamboo, the tree being split 

 into two pieces and the pith removed, the pieces being again fastened 

 together with rope. 



I remain, dear sir, yours truly, 

 John Campbell, 



Assistant Surveyor General, 



23d August 1837. 



