Numb. 438. 
PHILOSOPHI CAL 
TRANSACTIONS 
For the Months of July, Auguft and Septem. 173 
The CONTENTS. 
I. The Defcription and life of an Arithmetical 
Machine invented by Chriftian-Ludovicus 
Gerften, F. % S. Frofeffor of Mathematicks 
hi the Unt’Verfity of Gieflen. In/cribed to 
Sit Hans Sloane, Fart* Frefident of the 
Royal Society. 
II. Of the Figure of the Earth, and the Variation: 
of Gravity on the Surface^ <By Mr* James 
Stirling, F.^.SV 
Ill* Filtri Lapidis Mexicani Examinatio et Compa- 
ratio cum aliis lapidibus fabta, qua denionftratur , 
nullum Vel exiguum ejus ufum effe in depuranda. 
aqua per ilium colata: Auclors Abrahamo 
Yatero, M. D. et *P. *?. Societ. Imper. 'Hat* 
Cur. et <%eg. Britann- et Borufl. Socio. 
IV. A 
