C '5 3 
given,to GL; and as R^^w to Tangent ofFGB/fb GjVI to 
LM. Then LM—MX in heights^ or-^-MX in defcems ; or 
elfe MX— ML, if the direBion be below the H rlzomal-lmt] 
is the fall in the time that the dire9: impdfe given in G would 
have carried the ProjeB from G to L=:LXc::GY ; then by 
iX2iConofthQ Par aiola y asLXor GY^ istoGL or YX, :: ib 
is GL to the P^r.w-^t'/^(?r fought. To find the Felocitj of the 
Impulfej by Prop.2,&:Ay find the time in fecondsth^fSihody 
would fall the j^^r^ LX, and by that dividing the lineGl^, 
the Qmte will be the Velocity^ or J^ace moved in a feccnd 
fought, which is alwaies dimean froportioml between the Pa- 
rameter and i6 feet i inch. 
Prof, X. Problem 2. Having the Parameter, Horizontal di- 
ftance, andheight ordefoentofan O^jV^, to find the Eleva- 
tions of the line dire cf ion necelTary to hit the given Ohject ; 
that is, having GM, MX, arid the greateft Kandon equal to 
half the Para^neter ; to find the Angles FGB. 
L€t ^^Tangent of the Jngle fought be ^t, the Horizontal 
^//^/^r^f GM=^, the Altitude of the O' jectMX^h^ the Pa- 
rameter=p, and Radi^~ry and it will be, 
As r to fo ^ to -=ML and — + h defcents==^^^^^^^^ 
p 1 1? U^p h =^ GL quad. =XY qmd. ratione ParaboU ] but 
r 
b ^ ==:GL iiuad. 47. I. Euclid, Wherefore 
r r 
^~~^f h-==='hh-^^-^^ is 
ilAA p h—h b, divided by ^ 
r r r ^ ^ 
^L^=f^^f^ — I. this Equation fhews the Queftion to 
have two Anfwers, and the Roots thereof are --f '=z^y^^ 
VjJ±Ath_ J from which I derive the following Rule. 
4 bb 
