VOL. XXX.] PHILOSOPHICAL TRANSACTIONS* 340 



hole, and its standing in the larger and lower. And if it shall be found that it 

 was a very windy day when this accident happened, it will niuch add to the 

 probability of this solution. 



An accident not unlike this lately happened in Fleet-street, London, by the 

 defect of the arched roof of a very deep common sewer. The earth gradually 

 falling into the sewer was carried away by it, so as not to obstruct the water; 

 and the continual tremor of the ground, occasioned by the constant passing of 

 carts and coaches, gradually shook down the earth, so as to leave a very great 

 cavern, the top of which at length became so very thin, that one day a weighty 

 cart having just passed it, a large space of the pavement sunk in, in the middle 

 of the street, not without hazard to a coach then driving by. 



A Rectification of the Motions of the Five Satellites of Saturn, with some accurate 

 Observations of them. By the Rev. Mr. James Pound, F. R. S. N° 355, 

 p. 768. 



Above 30 years since, Mr. Cassini communicated his discovery of two new 

 satellites of Saturn, which made their number five; and his account of them is 

 to be seen in N° 187. About the same time M. Huygens presented to the 

 Society the glasses of a telescope ] 25 feet long, with the apparatus for using 

 them without a tube; by help of which we might have satisfied ourselves of 

 the reality of these discoveries. But those here who first tried to use this glass, 

 for want of practice, finding some difficulties in the management of it, caused 

 it to be laid aside for some time. Afterwards it was designed for making per- 

 pendicular observations of the fixed stars passing by our zenith, to try if the 

 parallax of the earth's annual orb might not be made sensible in so large a 

 radius, according to what Dr. Hook had long since proposed ; but in this we 

 miscarried also, for want of a place of sufficient height and firmness, on which 

 to fix the object-glass, so that it lay by neglected for many years. 



In the mean time we could not but remark a great reserve in the French 

 astronomers in regard to these satellites, of which they have given us in their 

 memoirs no observations till very lately, nor have they seemed willing to show 

 them in their glasses to such as requested it: so that it might possibly occasion 

 in some persons a suspicion of the reality of this discovery ; and Mr. Derham, 

 having borrowed the Society's long glass, could not by it assure himself that 

 the small stars he sometimes found about Saturn were really his satellites, their 

 situation not agreeing with their places derived from the tables of their motions 

 exhibited in N° 187, besides that he wanted a sufficient height to raise the ob- 

 ject-glass, so as to view Saturn to advantage, above the vapour of the horizon. 

 But in the Memoirs for 1714, M. Cassini, the younger, has given us some 



