HYDRAULICS. 177 



To prove this by experiment : let two pipes of 

 equal sized bores be fixed into the side of a vessel, 

 one pipe being four times as deep below the sur- 

 face of the water in the vessel as the other is ; 

 and whilst the pipes run, let water be poured con- 

 stantly into the vessel, so as to keep it always full. 

 Then, if a cup that holds a pint be so placed as to 

 receive the water that spouts from the upper pipe, 

 and at the same moment a cup that holds a quart 

 be placed to receive the water from the lower pipe, 

 both cups will be filled at the same time by their 

 respective pipes. 



The horizontal distance to which a fluid will 

 spout from a horizontal pipe, in any part of the 

 side of an upright vessel below the surface of the 

 fluid, is equal to twice the length of a perpendi- 

 cular to the side of the vessel, drawn from the 

 mouth of the pipe to a semicircle described upon 

 the altitude of the fluid : and, therefore, the spout 

 will be to the greatest distance possible from a 

 pipe whose mouth is at the centre of the semi- 

 circle ; because a perpendicular to its diameter, 

 (supposed parallel to the side of the vessel) drawn 

 from that point, is the longest that can possibly be 

 drawn from any part of the diameter to the cir- 

 cumference of the semicircle. 



Thus, if the vessel A B (Plate 8. fig. 12.) be 

 full of water, the horizontal pipe D in the middle 

 of its side, and the semicircle NECbe described 

 upon D as a centre, with the radius or semidia- 

 meter D C, or D N, the perpendicular D £ to the 

 diameter C D N is the longest that can be drawn 

 from any part of the diameter to the circumfer- 

 ence : and if the vessel be kept full, the jet will 

 spout from the pipe D to the horizontal distance 



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