ACTING BY A CLOSED COLUMN OF WATER. 103 



K L, is a tumbler or tumbling bob, capable of being moved |g£^* 

 on the gudgeons V, from its prefent pofition to another, in t h e defcent of a 

 which the weight L mail hang over with the fame inclination column indofed 

 on the oppofite f^de of the perpendicular, and consequently 

 the end K will then be as much elevated as it is now de- 

 prefled. 



The pipe R S has its lower end immerfed in a cittern, by 

 which means it delivers its water without the poffibility of the 

 external air introducing itfelf ; fo that it conflitutes a torricel- 

 lian column, or water barometer, and renders the whole co- 

 lumn from A to S effectual, as we (hall fee in our view of the 

 operation. 



The operation. Let us fuppofe the lower bar KX of the Operation, or 

 tumbler to be horizontal, and the rod F O fo fituated, as that £°* ing ? r0 * 

 the plugs or leaden piftons D and E mall lie oppofite to each 

 other, and flop the water ways G and F. In this ftate of the 

 engine, though each of thefe piftons is preffed by a force equi- 

 valent to more than a thoufand pounds, they will remain mo- 

 tionlefs, becaufe thefe actions being contrary to each other, 

 they are conftantly in equilibrio. The great pifton H being 

 here fhewn as at the bottom of its cylinder, the tumbler is to 

 be thrown by hand into the pofition here delineated. Its 

 a&ion upon O F, and confequently upon the wheel Q, draws 

 up the plug D, and deprefles E, fo that the water way G 

 becomes open from A B, and that of F to the pipe R : the 

 water confequently defcends from A to C ; thence to G G G, 

 until it acts beneath the pifton H. This prefTure raifes the 

 pifton, and if there be any water above the pifton, it caufes 

 it to rife and pafs through F into R. During the rife of the 

 pifton, (which carries the pit-rod M N along with it) a Aiding 

 block of wood I, fixed to this rod, is brought into contact 

 with the tail K of the tumbler, and raifes it to the horizontal 

 pofition, beyond which it overfets by the acquired motion of 

 the weight L. 



The mere rife of the pifton, if there were no additional mo- 

 tion in the tumbler, would only bring the two plugs D and E 

 to the pofition of reft, namely to clofe G and F, and then the 

 engine would ftop ; but the fall of the tumbler carries the plug 

 D downwards quite clear of the hole F, and the other plug E, 

 upwards quite clear of the hole G. Thefe motions require no 

 confumption of power, becaufe the plugs are in equilibrio, as 

 was juft obferved. 



M 2 In 



