1Equable, though unequal to one another, made the one along the
Horizontal Line, and the other along the Perpendicular, for I very
well comprehend that there is made a Motion of theſe two poten
tia equal to both the Compounding Motions, but my confuſion
ariſeth upon the mixing of the Equable-Horizontal and Perpendi
cular-Naturally-Accelerate Motion. Therefore I could wiſh we
might toge ther a little better conſider this buſineſs.
Horizontal Line, and the other along the Perpendicular, for I very
well comprehend that there is made a Motion of theſe two poten
tia equal to both the Compounding Motions, but my confuſion
ariſeth upon the mixing of the Equable-Horizontal and Perpendi
cular-Naturally-Accelerate Motion. Therefore I could wiſh we
might toge ther a little better conſider this buſineſs.
SIMP. And I ſtand the more in need thereof in that I am not
yet ſo well ſatisfied in Mind as I ſhould be, in the Propoſitions that
are the firſt foundations of the others that follow upon them. I
will add, that alſo in the Mixtion of the two Motions Equable
Horizontal, and Perpendicular, I would better underſtand that
Potentia of their Compound. Now, Salviatus, you ſee what we
want and deſire.
yet ſo well ſatisfied in Mind as I ſhould be, in the Propoſitions that
are the firſt foundations of the others that follow upon them. I
will add, that alſo in the Mixtion of the two Motions Equable
Horizontal, and Perpendicular, I would better underſtand that
Potentia of their Compound. Now, Salviatus, you ſee what we
want and deſire.
SALV. Your deſire is very reaſonable: and I will eſſay whe
ther my having had a longer time to think thereon may facilitate
your ſatisfaction. But you muſt bear with and excuſe me if in diſ
courſing I ſhall repeat a great part of the things hitherto delivered
by our Author.
ther my having had a longer time to think thereon may facilitate
your ſatisfaction. But you muſt bear with and excuſe me if in diſ
courſing I ſhall repeat a great part of the things hitherto delivered
by our Author.
It is not poſſible for us to ſpeak poſitively touching Motions and
their Velocities or Impetus's, be they Equable, or be they Naturally
Accelerate, unleſs we firſt agree upon the Meaſure that we are to
uſe in the commenſuration of thoſe Velocities, as alſo of the Time.
As to the Meaſure of the Time, we have already that which is
commonly received by all of Hours, Prime-Minutes, and Se
conds, &c. and as for the meaſuring of Time we have that com
mon Meaſure received by all, ſo it is requiſite to aſſign another
Meaſure for the Velocities that is commonly underſtood and re
ceived by every one; that is, which every where is the ſame. The
Author, as hath been declared, adjudged the Velocity of Naturally
deſcending Grave-Bodies to be fit for this purpoſe; the encreaſing
Velocities of which are the ſame in all parts of the World. So that
that ſame degree of Velocity which (for example) a Ball of Lead of
a pound acquireth in having, departing from Reſt, deſcended Per
pendicularly as much as the height of a Pike, is alwaies, and in all
places the ſame, and therefore moſt commodious for explicating
the quantity of the Impetus that is derived from the Natural De
ſcent. Now it remains to find a way to determine likewiſe the
Quantity of the Impetus in an Equable Motion in ſuch a manner,
that all thoſe which diſcourſe about it may form the ſame conceit
of its greatneſs and Velocity; ſo that one may not imagine it more
ſwift, and another leſs; whereupon afterwards in conjoyning and
mingling this Equable Motion imagined by them with the eſtabli
ſhed Accelerate Motion ſeveral men may form ſeveral Conceits of
ſeveral greatneſſes of Impetus's. To determine and repreſent this
their Velocities or Impetus's, be they Equable, or be they Naturally
Accelerate, unleſs we firſt agree upon the Meaſure that we are to
uſe in the commenſuration of thoſe Velocities, as alſo of the Time.
As to the Meaſure of the Time, we have already that which is
commonly received by all of Hours, Prime-Minutes, and Se
conds, &c. and as for the meaſuring of Time we have that com
mon Meaſure received by all, ſo it is requiſite to aſſign another
Meaſure for the Velocities that is commonly underſtood and re
ceived by every one; that is, which every where is the ſame. The
Author, as hath been declared, adjudged the Velocity of Naturally
deſcending Grave-Bodies to be fit for this purpoſe; the encreaſing
Velocities of which are the ſame in all parts of the World. So that
that ſame degree of Velocity which (for example) a Ball of Lead of
a pound acquireth in having, departing from Reſt, deſcended Per
pendicularly as much as the height of a Pike, is alwaies, and in all
places the ſame, and therefore moſt commodious for explicating
the quantity of the Impetus that is derived from the Natural De
ſcent. Now it remains to find a way to determine likewiſe the
Quantity of the Impetus in an Equable Motion in ſuch a manner,
that all thoſe which diſcourſe about it may form the ſame conceit
of its greatneſs and Velocity; ſo that one may not imagine it more
ſwift, and another leſs; whereupon afterwards in conjoyning and
mingling this Equable Motion imagined by them with the eſtabli
ſhed Accelerate Motion ſeveral men may form ſeveral Conceits of
ſeveral greatneſſes of Impetus's. To determine and repreſent this