CONTENTS. 
V. An Account of an Earthquake felt at Llfbon, 
December 26, 1764: In a Letter to the Rev. 
Samuel Chandler, D. D. F. R. S. p. 43. 
V J . An Account of the White Negro Jhewn before the 
Royal Society : In a Letter to the Right Nonourahle 
the Earl' of Morton, Prefident oj the Royal Society ^ 
from James Parfons, M. D. F. R. S. p. 45. 
\" 1 I. An Account of an Improvement made by Mr. 
Peter Dollond in his New Felefcopes : In a Letter 
to James Short, M. A. F. R.S. with a Letter of 
Mr. Short’s to the Rev. Thomas Birch, D. D. 
Secret. R. S. p. 54. 
VIII. Some Account of a Salt found on the Pic of 
Teneritte, by W. Heberden, M. D. F.R. S. p. 57. 
IX. Short and eajy Methods for finding ( i .) Fhe ^puan- 
tity of Time contained in any given Number of 
Mean Lunations -y (2.) Lhe Number of Mean Lu- 
nations contained in any given ^antity of f ime ; 
(3.) The Number of Froy Pounds contained in any 
given Number of Avcirdupoife Pounds^ and vice 
verfa; (4.) Fhe ^lantity and Weight of Water 
' contained in a full Pipe of any given Height y and 
Diameter of a Bore-y and confequenthy to fnd what 
Degree of Power would be required to work a com- 
mon Pumpy or any other Hydraulic Engine, when 
the Diameter of the Pump- bore, and the Height to 
which the Water is to be raifed therein, are given. 
Communicated by Mr. James Fergulbn, F. R. S. 
p. 61. 
X. A Recommendation of Hadley’s S^uadrant Jor fur - 
vcyingy efpecially the furveying of Harbours, together 
with a particular Application of it in forne Cafes of 
Pilotage. By the Rev. John MichelJ, B. D. 
F.R. S. p. 70. 
XI. An 
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