THE TIDES. 171 



us results of observations. 1 Here is such an 

 instrument a tide gauge (Fig. 25). The floater 

 is made of thin sheet copper, and is suspended by 

 a fine platinum wire. The vertical motion of the 

 floater, as the water rises and falls, is transmitted, 

 in a reduced proportion by a single pinion and 

 wheel, to this frame or marker, which carries a 

 small marking pencil. The paper on which the 

 pencil marks the recording curve, is stretched on 

 this cylinder, which, by means of the clockwork, 

 is caused to make one revolution every twenty- 

 four hours. The leaning-tower-of-Pisa arrange- 

 ment of the paper-cylinder, and the extreme 

 simplicity of the connection between marker 

 and floater, constitute the chief novelty. This 

 tide-gauge is similar to one now in actual use, 

 recording the rise and fall of the water in the 

 River Clyde, at the entrance to the Queen's 

 Dock, Glasgow. A sheet bearing the curves 



1 The various instruments and tide-curves referred to in this lecture 

 are fully described and illustrated in a paper on " The Tide Gauge, 

 Tidal Harmonic Analyser, and Tide Predicter " read before the In- 

 stitution of Civil Engineers, on 1st March, 1881, and published in 

 their Proceedings for that date. 



