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XI. Description of a new Tide-Gauge, constructed hy Mr. T. G. Bunt, and erected on 

 the eastern hank of the river Avon, in front of the Hotwell House, Bristol, 1837- 

 Communicated hy the Rev. William Whewell, M.A. F.R.S. 8fc. 



Received March 15,— Read March 22, 1838. 



The principal parts of this machine are : 



A, an eight-day clock, which turns 



B, a vertical cylinder, revolving once in twenty-four hours : 



C, a wheel, to which an alternate motion is communicated by 



D, a float rising and falling with the tide, and connected with C by the wire E, 

 passing over the pulley F, and kept constantly strained by the counterpoise G : 



H, a small drum on the same axis with C, which, by a suspending wire, communi- 

 cates one-eighteenth of the vertical motion of the float to 



I, a bar carrying a pencil, K, which marks a curve on the cylinder B, so as to show 

 the time and height of high water. 



The above will convey a general notion of the machine and its use ; but it will be 

 necessary to enter more into detail. 



a (figs. 1, 2 and 3) is a strong oak frame secured to the quay wall ; b is a maho- 

 gany frame resting on the arms c c, which are supported by the pillars d d ; e is a 

 bracket resting on a pillar f, and sustaining the cylinder B. The lower pivot of the 

 cylinder has its bearing in a small cylindrical plug h (fig. 5.), which may be lowered 

 by a screw and a winch, as seen in the figure, so as to disengage, first the upper pivot, 

 and afterwards the lower one, when the cylinder may be drawn out of its place, being 

 made to slide forwards horizontally on the two cross pieces a a. 



The pencil K, fig. 4, is inserted into a tube soldered to the brass bar d. This bar 

 moves without shake, on a long axis e, so as not to require side friction to guide it, 

 while it is pressed forwards against the cylinder by the weight and bent lever L ; 

 y is a small bolt for holding back the pencil, when necessary, by thrusting it into the 

 stud g; ^ is a nut and screw for adjusting the height of the pencil to the scale. The 

 pencil is guided vertically by a mahogany bar N, fig. 3, having a groove in its edge 

 for receiving the ivory wheel o, which is pressed gently against N by the brass rod P, 

 slightly curved towards the pencil, to produce the requisite pressure. Q Q are two 

 other brass rods (or tubes) for guiding the lower end of the pencil bar I, by means of 

 the cross guide R, fitted loosely on the rods. The guide N is adjusted, or may be 

 drawn out, by means of a notch in the board T, which supports it, the top of the bar 

 being held by a tenon. The pillar d is represented as broken off, for the purpose of 



MDCCCXXXVIII. 2 K 



