WATER. 



Dcfcrlption of the Aperture through which 

 the Water flows. 



ffnlf. — In takinsr the meafure for the depth 

 of the colurun wliich produces the velocity, 

 we may in general take it from the furface 

 of tlie water to tlie centre of the aperture; 

 but if the aperture is in a perpendicular 

 plane, and of a height greater than one- 

 fourth of the whole depth, then the velo- 

 city muft be found for the top of the aper- 

 ture and alfo for the bottom of the aperture, 

 and tlie mean of both taken for the mean 

 velocity of the water. 



Ratio 



between the 



real velocity 



and the 



tlieoretic 



velocity, or 



that which is 



due to the 



wholeDej)ih, 



as Qiewn by 



our firft 



Tuble. 



To find tlie Velocity of the IfTuihg Water. 

 Rule. — Extmfl the Square Root of the Depth, (roeafurcd from 

 the Centre of the Orifice to the Surface of the Water,) and 

 multiply by forae One of the following Numbers, accordinj 

 to the CircumllancK of the Cafe. 



I. 



When it is required to know 

 the Velocity in Feet per Second 



II. 



When it is required to know 

 the Velocity in Feet per Minute 



If the Depth 



is in Feet 

 multiply by 



If tha Depth 

 is in Inches 

 multiply by 



If the Depth 

 is in Feet 



multiply by 



If the Depth 

 is in Inches 

 multiply by 



To find the Number ot 



Cubic Feet of Water 



which flow per Minute 



through each Squftre 



Ineli of the Area. 



Kthe 

 Depth is 

 in Feet 



extract the 



SquHre 



RtH)t and 



multiply by 



If ihe 



Depth is 



in Inches 



extract tlie 



Square 



Root and 



multiply by 



For a (hort 

 cylindrical 

 pipe from 

 two to . 

 four times 

 as long as 

 the bore, 



For orifices in a thin plate 

 For the openings of fluices or 

 apertures in the fide or internal 

 walls of the refervoir, without 

 any fide walls which can ferve 

 to conduft the particles of wa- 

 ter in a ftream to the aperture 

 " I. When it projefts 

 withinfide the vefTel 

 and does not run 

 with a full bore of [> 

 water, but in form 

 of a contrafted vein 

 within the tube 



2. When it projefts 

 withinfide the veflel 

 but runs with a full 

 bore of water 



3. When it does not 

 prujeft withinfide 

 of the veflel - 



Fornarrow openings, of which the 

 bottom is on a level with that of 

 the refervoir. Alfo for fmaller 

 openings of fluices, when pro- 

 vided with fide walls to conduft 

 the water to the aperture; alfo ■ 

 for the water-paflage under 

 bridges which have fquare piers 

 with abrupt projeftions, which 

 do not conduft the water regu- 

 larly into the paflage 



For wide openings, of which the" 

 bottom is on a level with that 

 of the refervoir ; alfo for large 

 fluices with condufting walls 

 in the direftion of the ftream }> 

 and for the water-way beneath 

 bridges vnth pointed piers, 

 which conduft the water into 

 the paflage 



For a circular orifice or tube formed ' 

 correfpondent to the contrafted ■ 

 ftream - - - - 



For the whole velocity due to the ' 

 height according to the theo- ■ 

 rems for falUng bodies 



.618 



.636 



•5137 



.681 



.8125 



.860 



.960 



•983 



1. 000 



4-957 



4. 1 19 



5.46 

 6.515 



6.9 



7-7 



7.884 



8.019 



1-431 



1.472 



1. 190 



1.576 



1.881 



.992 



2.223 



2.276 



2.3148 



297-45 



306. 



247.14 



327.6 



390-9 



414. 



462. 



473-04 



481.14 



85.87 



88.32 



71.40 



112.86 



119.52 



133-38 3-2o8 



136.56 



138.888 3.349 



.065 



•59633 



2.125 -^133 



1.716 



94.56 2.275 



2.729 



2.875 



3-285 



.4958 



.6566 



-7837 



.830 



.9262 



-9483 



.9645 



