A Difcourfe concerning the Meafnre of the Airs re- 
Jijiance to Bodies moz^ed in it. By the Learned 
]o\in^N2i\Xis S. 7.D.&K.S.S0C. 
I. ' 1 Hat the Air ( and the like of any orher Medi- 
1 urn') doth confiderably give refinance to Bo- 
dies moved in it ; ( and doth thereby abate their Celerity 
and Force :) is generally admitted. And Experience doth 
atteft ic ; For otherwife, a Cannon Bulkt projefted Hori- 
zontally, ftiould ( fuppoling the Celerity and Force undi« 
minifhed ) ftrike as hard againft a perpendicular Wall, e- 
refted at a great diftance, as near at hand ; which we find 
it doth not. 
2. But at what Rate, or in what Proportion, fuchre- 
fiftance is ; and ( confequently, at what Rate the Celeri- 
ty and Force is continually diminifhed ) feems not to have 
been fb well examined. Whence it is, that the Motion 
of a Projeft ( fecludmg this Confideration ) is commonly 
reputed to defcribe a Parabolick Line ; as arifing from an 
Uniform or equal Celerity in the Line of Projedion, and 
a Celerity uniformly accelerated in the Line ofDefcent: 
which two lb compounded, do create a Parabola, 
3. In order to the computation hereof; I firftpremilc 
this Lemmaj ( as the moli rational that doth occur for my 
firft footing, ) That ( fuppofing other things equal ) the 
refiftance is proportional to the Celerity. For in a double 
Celerity, there is to be removed (in the lame time) twice 
as much Air, (which is a double Impediment) in a treble, 
thrice as much ; and fb in other Proportions. 
4. Suppofe we then the Force imprelTed ( and con- 
fequentiy the Celerity, if there were no refiftance j as J j 
the refiftante as r. (which muft be lefs than the Foi'ce, or 
elie the Force would not prevail over the Impediment , to 
create a Motion.) And therefore the effeftive Force at a 
firft Monii;nt,i::. to be reputed as i— : That is, fo much as 
L I 2 the 
