Divide half the Par meter by the Horizontal diftance, and 
keep the (^ote; -uiz. -^then fay, ^s.fquare of tlyQdiJIance 
given to the half Parameter , fb half Parameter double 
deta ^^^^^/^^^^^ 
thz Tangent anfwering to that 6>r^/?/^, will be 
or rr : fo then the fum and diiffercnce/ of the afore-found 
Quote, and this Tangent will be the Roots of the Equation^ 
and the Tangents of the Elevations fought. 
Note here, that in Defcents, if the Tangent exceed the 
Qjwtej as it does when fh is more than hb^ the direBion of the 
lower Elevation will be below the Horizon, and if fh=U, it 
muft be direfted Horizontal, and the Tangent of the upper 
Elevation will be^^iNote likewife,that if 4^^-|-4/>/r in afcentSj 
or 4 hb-'^ph in defcents, be equal to there is but one f/^'zr^- 
, p r 
tion that can hit the Ol?je^^ and its Tangent is and if 
4^^4*4/^^ ^centSyOV /\hb—^ph in defcents^Ao exceed //,the 0^- 
jVt? is without the reach of a Project caft with that Velocity ^ 
and fo the thing impoflible. 
From this Equation ^hhJf^^ ph=pp are determined the ut- 
moft limits of the reach of any Project, and the Figure affign^ 
ed, wherein are all the heights upon each Horizontal diflance 
beyond which it cannot pals ; tor by reduftion of that £- 
quation^ h will be found =: \p— ~ in heights^ and ^-y —'p in 
defcents \ from whence it follows, that all the Points h are in 
the CVt^^ of the Parabola ^ whoik Focus is the Point from 
whence the Proje^ is caft, and whole Latus re^fum^ or Para 
meter ad Axem is=p. Likewife from the fame Equation may 
the lod,{\: Parameter ov Velocity be found capable to reach th^ 
Object 
