( 6069 ) 
The treats of the dcfceDt of Heavy bodies^and 
Motion ip a€;^^/t?/^j that B; in a Line, which aNail^faftri'd iii 
the'drea-mfereoce of a riiaiiiog wheel 3 -by its - coatinued cir- 
cuxn-rotatioo deligactb io the Aitv"- 
The Third y O[ the Evolatioa and Dimeufion of Cu ve 
The Fourth^ of the Center of ^VibratioEi* 
TheF///A,of the cooftrudioQ of an other Watch 3 where- 
IB the Pendulum movti\x Cireularty, together with fotne The» 
Why the Author hath joy ncd all thefe matters together in 
this Book, will appear from his own difcourfe pretnifed ia the 
beginning of thefamei €t leems then^ that having, fiacethe 
publication of his fif ft Traft concerning the Watches by him 
invented , found many things relating to the perfedion of 
that work, he thought good to gratify the publick with themj 
clpecially feeing that thefe Particulars are by him lookt upon 
as the liiaid^and, as 'twere, the ground of this whole Mecha- 
niftn 5 which before it was dcftitute of. For, a fiinple Pen- 
dulum being uo Gertaia and Equal Meafure of time, in regard 
that larger excurfions are obferv'd to beflower than the nar- 
rowcrjhe hath by the aid of Geometry lighted upon a way of 
fufpending the Pendulum^ by finding out a certain Curve Line, 
that is appropriate to giveit that defired Equality, which ha- 
ving applied to Watches, their Motion hath by this means 
been rendred fo conftantand certain, chat by freqaent Expe- 
riments they are now known to be exceedingly ufeful both ia 
Aftronoroy and N ivigation* This being the Cfcloid^bovt- 
mentipned^our Author maketh it his chiefbufinefs in this Trea- 
tifc to give a very accurate damonftracion thereof* To which 
he thought It fcquifice td prcmiie fbme new Demonftrations 
to eftablifli and advance the Doarine oiGaliUi touching th e 
Defcent of Heavy ho dies ^ the fop-fruit of which he couots to' 
be this very propriety of the Cy<£^/^i<^* 
But then that this Cycloid inight be adapted to the life of 
Pendulums^ he thought hitislelf obliged to enter upon a riew 
coniiderationbf Curve Liries, viz. of thofe, which'by their 
Evolution gener2it€ other Cur vcsi Whence refulted t4ie corn-' 
' LI 1 111 2 parifon 
