Numb. 4x4 
PHILOSOPHICAL 
TRANSACTIONS 
For the Months of July, and Jiugufi , i73x. 
The C O N T E N T S. 
I. An Extract from the Minutes of the Royal 
Society, March 16, 1751, containing an 
uncommon Cafe of a Diftempered Skin, />jJohn 
Machin, Sec. S. Brof. Aflr. Grefh. 
II. Conjectures upon the Nature of Intermitting 
and Reciprocating Springs. ’Ey Mr. Jofeph 
Atwell, F. % S. 
III. Immerjiones, atque Emerfiones Satellitum Jo- 
vis ObferVat# Pekini d <P <P. Ignatio Kegler, 
OAndrea Pereira, Soc. Jesu,^ wen/eNovem. 
1750, ad^e\> d ' P. Johannem Baptiftam Car- 
bone, Soc. Jesu, Y(. S. S- ttanfmiffjc 5 et exr 
ejufdem Cl. Viri Epifiola ad Jacobum de Ca- 
ftro Safmento, M. T>. Col Medic. Lond, 
L. <sr 5 . 5 . excerptae. 
IV. A Catalogue of Eclipfes of Jupiter’s Sa- 
tellites for the Year 1753, By James 
Hodgfon, F. % S. Mafler of the <%pyal Ma- 
thematical School at Chrift’s Hofpital, London. 
V.- 
