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when placed on a common table which is too low ; let a metal 

 pipe conneded with the rec' at C, or D, fig. 2. have an arm 

 fifing upwards to the height neceffary to conned it with the 

 open top of the bar"^ tube, whofe ciflern may be fupported by 

 a board faftened below to the frame of the table. Thus every 

 neceflity will be prevented for conftruding the pump with an 

 unportable frame. 



In order to make each of the duds, which have now been 

 defcribed, communicate alternately with the barrel, it is necef- 

 fary that the key of the cock fhould receive a motion of one 

 quarter of a turn, the duds in it being at right angles to 

 each other ; and confequently it muft have detents to confine 

 it to that motion : this is effeded by a pin «, fixed perpendi- 

 cularly in the back of the handle «, fig. i. which pin, when 

 the handle is put on the fquare end of the key (and fecured 

 there by a winged nut) defcribes a quadrantal arch under the 

 fhell of the cock, where there is juft room to allow fuch a 

 motion of the pin, a part of the ridge of metal at the back 

 of the cock, being hollowed out for that purpofe ; and care was 

 taken that the duds in the key, when at the limits of its due 

 motion, exadly correfponded with the holes in the fiiell ; the 

 key not being pierced 'till the handle was fittted on, and thefe 

 limits afcertained. The joinings of the cock to the barrel, and 



U u 2 of 



