Pr.Chriftopher Wrens 
Theory concerning the fame Subject % imparted to the R. So- 
ciety Decemb. ij.Uft, though entertain d by the Author di- 
vers years ago\ and verip d by many Experiments 5 made by 
Himfelf and that other excellent Mathematician M. Rook be- 
fore the f aid Society ^ as is attefed by many Worth] Members 
of that Illuftrious Body. 
Lex Nature de Collifione Corporum. 
'TJElccitates Ccrporum propria & max ime Nat males ' fmt ad Corpora n- 
V . ciproce proportion ales. 
f Itacjue Corpora R, S. habentia propria* Velochat.es , etiam pofi Jm« 
\ fydjum retineniproprias. 
Lex Na- 1 Et Corpora R. S. impr&prias Velocitates habentia ex Imfulfu re- 
turn. 1 fikmntur ad ^Equilibrium ; hoc eft, ^uanmmKfuperat^ & 
$ deficit a propria Ve lock ate ante Impulfum, t ant urn ex Impulfa 
I abftrahitur ab R & additur ipfi S e contra, 
Sjiare Collifto Corporum froprias Velocities habendum aquipollet Libra 
ofcilhnti fuper Centrum GravitatU, 
Et Collifio Corporum improprias Velocitates habentium aquipellet Libra fa- 
per bind Centra aqualiter huk inde h CentroGravitatis diftantia % Libra ve- 
ro Jugum , ubi opus eft i producitur. 
Itaque Corporum aqnalium impropne moventium tres funt cafus . Corporum 
vers inxqualium improprU moventium {five ad contr arias five ad eafidem 
partes ) decern funt omnino Cafus , quorum quinqut oriuntur ex Conver- 
Inkquaiia., , ' ^E'qualia, 
