4^4 Difcbarge of Water [Book Vll , 



fervoir, and at different diftances from^ the fonrce or 

 refervoir, are to each other nearly in an inverfe pro 

 portion of the fquare roots of thefe diftances; 



It may be obferved from the preceding table, that 

 a pipe of one inch and one-third diameter furnifhes 

 lefs water in proportion than one of two inches diame* 

 ter, under the fame height of the refervoir, and of the 

 fame length. The reafon of this is, becaufe there is, 

 relatively to the quantities of water which thefe pipes 

 will contain, more furface of friction in the fmall pipe 

 than in the larger one. 



If the fame pipe was curvilinear inftead of being ftraitj 

 the difcharge would ftill be diminished from this circum- 

 fiance, though not in any confiderable degree , but the 

 diminution would be ftill greater if the curvilinear pipe 

 was placed in a vertical inftead of a horizontal pofi- 

 tion. The diminution (fmall as it is) is produced by 

 the refiftance which the water meets in running againft 

 the angles of the pipe, which deprive it of a part of 

 its velocity. 



But if the pipe, inftead of being curvilinear, was 

 angular in feveral points, the diminution would be 

 greater, and the more fo in proportion as thofe angles 

 fhould be more acute, becaufe then the refiftance to 

 the water would be more direct. When the pipes are 

 curved, and their curvature vertical, as in Plate X* 

 Fig. i. there are then declivities and afcents in which 

 the air will lodge, and refift or even impede the courfe 

 of the water. For example, let A B C D E F G be a 

 pipe, the upper extremity of which A anfwers to a re- 

 fervoir which fupplies it with water, and the extremity 

 G goes to furnifh a fountain. The pipe being filled 

 with nothing but air, and water being made to run 

 from A, this water will drive the air before it, and fill 

 the portion of the pipe A B more than the portion 



