M/\ smeaton on Mechanic Fozve}\ 
double work only; « becaufe (the adjutage being the 
lame), lays he, we find, that as the water’s velocity is 
double, there are twice the number of particles of 
„ * hat lffue out > therefore the ladle-board is 
truck by twice the matter, which matter moving with 
„ th * J elocit y that k had in the firft cafe, the 
whole effect mult be quadruple, though the inban- 
• taneous ltroke of each particle is increafed only in a 
imple proportion of the velocity.” See vol. II. Anno- 
tations on lecture 6th, p. 92. 
_ A S ain > i n tlle iame volume, lecture 1 2th, p. 424.. re- 
el ring to what went before, he tells us, “ The know- 
“ led g e °f the foregoing particulars is abfolutely necef- 
‘ faiy for fetting an underfhot wheel to work; but the 
“ advantage to be reaped from it would be bill gue f s _ 
“ work ’ and we dtould be bill at a lofs to find out the 
“ utmoft it can perform, if we had not an ingenious 
“ propofition of that excellent mechanic M. parent of 
“ the Royal Academy of Sciences, who has given us a 
“ maximum m this cafe, by fliewing, that an underfliot 
“ wheel can d o the mob work, when its velocity is equal 
“ to the third part of the velocity of the water that 
“ dnves it, 8cc. becaufe then two-thirds of the water is 
“ em Ployed in driving the wheel with a force propor- 
“ tionable to the fquare of its velocity. if we muJ _ 
U tl l ,, y the lurface of the adjutage or opening by t’ - e 
“ hei S ht of the water > ™ fhall have the column of 
“ ter that moves th e wheel. The wheel thus moved will 
luftain on the oppofite fide only four-ninths of that 
weight, 
O o o 2 
u 
