CONTENTS 
O F 
VOL. LXX1II. Part I. 
t LETTER from William Herfchel, Efq. F. R. S. 
page i 
II. On the Diameter and Magnitude of the Georgium Sid us ; 
with a Defcription of the dark and lucid Dijk and Periphery 
Micrometers. By William Herfchel, Efq. F. R. S. p. 4 
III. CoKclufon of the Experiments and Obfervations concerning the 
Attradlive Powers of the Mineral Acids. By Richard Kir- 
wan, Efq. F R. S. p. 1 5 
IV. A Defcription of a Species of Sarcocele of a mof afonijhing 
Size in a B ack Man in the Jfand of Senegal ; with feme 
Account of its being an endemial Difeafe in the Country oj 
Galam. By J. P. Schotte, M. D. ; communicated by Sir 
Jofeph Banks, Bart . P. R. S. p. 85 
V. A Defcription of a new ConjlruSlion of Eye-glajfes for juch 
Tclefcopes as may be applied to Mathematical Injirutnents . 
