17S HYDRAULICS. 



M M, which is double the length of the perpen- 

 dicular D E. If two other pipes, as F and G, be 

 fixed into the side of the vessel, at equal distances 

 above and below the pipe D, the perpendiculars 

 F H and G I, from these pipes to the semicircle, 

 will be equal ; and the jets spouting from them 

 will each go to the horizontal distance N K, which 

 is double the length of either of the perpendiculars 

 F H or G I. 



The reader will easily perceive, that the curves 

 described by the spouting fluid, in all the different 

 situations, will be that of a parabola ; being acted 

 upon by the combined forces of the lateral pres- 

 sure of the fluid in the vessel, and the force of 

 gravity. 



When water issues through the aperture in the 

 side of a vessel, a smaller quantity runs out than 

 what might be expected from the pressure of the 

 fluid in the vessel ; because the stream is con- 

 tracted at a small distance from the aperture, 

 owing to the oblique direction of some of the parti- 

 cles of thewater in arriving at the aperture within, 

 and thus crossing each other as they come out. If a 

 short cylindrical pipe be added to the aperture, the 

 delivery is increased in a certain degree ; but a 

 much greater quantity flows when the short pipe or 

 ajutage, as it is called, is made of the form of a 

 frustum of a cone, the smaller end being towards 

 the vessel. 



We have seen that water will run through bended 

 pipes to the same level as the reservoir from which 

 it proceeds. So, also, if the pipe through which the 

 water issues in an open vessel be turned upwards, 

 the water will form a jet or fountain (see Plate 8. 

 fig. 12.), and will rise nearly as high as the surface 



