CONT ENTS. 
O F 
VOL. LXX. PartI.. 
I. /CALCULATIONS to determine at what Point in 
^ the Side of a Hill its AttraElion will be the greateft , 
life. By Charles Hutton, LL. D. and.F. R. S. In a 
Letter to Nevil Mafkelyne, D. D. E. R. S. and AJlro- 
nomer Royal.. ■ page i 
II. An Account of fome new Experiments in EleSlricity , 
with the Defcription and life: of two new Electrical In- 
Jiruments. By Mr. Tiberius Cavallo, F. R. S. com- 
municated by the Prefident. p. 15 
III. A new Method of ajfaying Copper Ores. By George 
Fordyce, M. D. F. R. S. p. 30 
IV. An Account of an .Eruption of Mount Vefuvius, which 
happened in Auguft, 1779. In a Letter from Sir Wil- 
liam Hamilton, K. B. F. R. S. to Jofeph Banks, Efq. 
P. R. S. p. 42 
V. An Appendix to the Paper in the Philofophical Pranf- 
a Elions for the Tear 1778, Number xlii, pages 902 
et J'eq. in tit led, “ A Method of extending Cardan’s 
“ Rule for refolving one Cafe of the Cubick Equation 
2 u x\ 
