(ioSt) 
Motion^ or the vpant ftrength^ by the length of 
time. 
a. Of the Defcent of Heayy Bodies^ and the Pe- 
climty of Motion^ Thirty four Propofitions. In which 
he doth not think fit to explicate the Phyfwal Caufe 
of Gratuity , whether it proceed from an innate qua- 
lity in the Heavy Body it felf , or an Univerfal Ten« 
dency of Circum-ambient Bodies to the Center^ or 
a Magnetical Power in the Earth , or the hke 5 but 
contents himfelf (his purpofe requiring no more y to 
underftand by the word Grayity ^ that fenfible force 
of moving downwards, or to a certain Point, both 
the Heavy Body it felf, and the lefs powerful Impedi- 
ments : Shewing in this Part alfoy in what propor-^ 
I tion the different Declivities ofObltque or Sloping 
Plains, in which a Heavy Body is fuppofed to be^ 
moved, doth operate to the Helping or Hindering 
of ftich Motion. All which he delivers as^^ generally) 
applicable to Motions, produced by any other force- 
as well as that of Gr^^/^^ 5. and dire^ed any others 
way as well as downward; 
' 3. The Do^rineof the EiBra^ ox BaUance (con- 
taining the Fwndamental Principles cA-^£tatich^ ,) 
in Twenty five Propofitions ^ among whiehy he ex- 
plains the Geometrical Confiderations requifite in 
making both exaft Cci/;^^/^?/^ Scales ^ and the K.c;^^^ 
. Qn-this o£ the Lihra^ : depends ^(that which is the^ 
&b)e€l:::Qf- the next - Part, -.almofl: finiiht^ atthe Pre&)^ 
die- whole Do&ine; o£ the Cmt^r of Graznty:^ 
