renew it till by the reck>very crf'^^:^^^ Sun| light they 
had recovered their former gayety and mirth : -How- 
ever we cannot learn that any Star' befides that of Fe- 
rns was difcovered by thofe which were fpeftators of 
|t in the open air. 
III. The Dimevfion cf the Solids generated by 
Co/^z/eryJo;^ 0/ Hippocrates 5 Lunula, and 
of its Parts about fever al Axes^ mth the Sur- 
faces generated by that Converfion^ by Ab. 
De Moivre, F. S". 
LEt BC A (Fig. lO be an Ifofcelles Triangle right 
angled at C. with the Center C, and diftance 
CB, defcribe the Quadrant B F A 5 on BA, as a Dia- 
meter, defcribe a Semicircle BRA $ the ^pace com- 
prehended between theQiadrantal arc B FA, and the 
Semicircumference B K A, is calFd Hifpocratess Lunula. 
li upon B C you take my two Points D, E5and draw 
the Perpendiculars D H,E M, meeting B A in I & L,and 
cutting a Portion F G M H of the LunuU 3 the SoUd 
generated by the conversion of this Portion about the 
Axis B C, is equal to a Prifm where Bafe is I L M H,and 
height the Circumference of a Circle whofe Diameter 
is B C 5 and the Solid generated by the Semicircle 
B K A, is equal to a Prifm or Semicylinder, whofe bafe 
is the Semicircle B K A, and height the Circumference 
of a Circle whofe Diameter is B C. 
Having bifefted B A in R. , and B C in P , the 
Surface generated by the converfion of the Arc H M a- 
bout the Axis BC,is equal to ^^bTThI^i"^'^^^ 
ffuppofing the ratio of the radius to the Circumference 
to 
