( 555" > Numb. i 9s - 
PHILOSOPHICAL 
TRANSACTIONS. 
OBober 19; 1691* 
The CONTENTS. 
i # A N Account of the fever al Species of 'Infinite 
XjL Quantity, and of the Proportions they bear 
me to the other, as it was read before the Royal So- 
ciety , by E. Halley. 2. A 'Bifcourfe concerning 
the Mufical Motes of the Trumpet and Trumpet- 
Marine, and of the DefeBsof the fame, by die Ho- 
nourable Francis Roberts Efcp> R. S. S. 3. An 
Account of tbeCaufeof the Change of the Variation of 
the Magneticai Needle, with an Hypotbefs of the 
Structure of the Internal parts of the Earth: as it 
was fropo/ed to the Royal Society, in one of their 
late Meetings, byfi. Halley. 
