THE TIDES. 185 



of the India Seas, the curves traced by the Tide- 

 Predicter from which is obtained the information 

 given in these Indian tide tables, do actually tell 

 the height of the water for every instant of the 

 twenty-four hours. 



The mechanical method which I have utilised 

 in this machine is primarily due to the Rev. F. 

 Bashforth who, in 1845, when he was a Bachelor 

 of Arts and Fellow of St. John's College, 

 Cambridge, described it to Section A of the 1845 

 (Cambridge) meeting of the British Association 

 in a communication entitled " A Description of a 

 Machine for finding the Numerical Roots of 

 Equations and tracing a Variety of Useful Curves," 

 of which a short notice appears in the British 

 Association Report for that year. The same 

 subject was taken up by Mr. Russell in a com- 

 munication to the Royal Society in 1869, "On 

 the Mechanical Description of Curves," l which 

 contains a drawing showing mechanism sub- 

 stantially the same as that of the Tide Predictor. 

 Here is the principle as embodied in No. 3 Tide 



1 Prof. Royal Society, June 17, 1869; (vol. xviii. p. 72). 



