174 PHILOSOPHICAL TRANSACTIONS. [aNNO ]6q7. 



lieved by the navel, in this manner. About the 17th month, the woman being 

 thougiit hydropical, lier navel began to swell and imposthiimate. It swelled 

 and grew livid of itself, and then broke and voided some quantity of ichorous 

 matter; by which the woman had some ease. In about a montli more it im- 

 posthnmated again, to a far greater degree than before ; on which the surgeon 

 opened it, where it seemed most jetting out, which was the navel itself; and 

 then after voiding a great deal of thin ichor and matter, there appeared some 

 bones, which startled him, not having seen the like before. It proved to be a 

 child, the flesh of which was decayed. After the extraction of the bones, the 

 woman was easy, and in a little time began to recover, she being very low, by 

 reason of the great burden she had carried for a long time. She is now re- 

 covered, and was alive about 6 months ago, wlien I was in Nevis ; and she has 

 had a child since. 



Concerning the Torricellian Experiment tried on the Top oj Snowdon-hill. By 



Mr. Halleij. N° 229, p. 582. 



Wednesday, May 26, I was on the top of Snowdon, where I tried the 

 Torricellian experiment with all the satisfaction I could wish for; the air con- 

 tinufd, both before and after, in the same state, as I got it verified by Mr. 

 Davis's standing barometer at Llanerch in Denbyshire, about 25 miles east from 

 Snowdon where it was observed during 4 days, to stand from 29.7-i- to 29.8-i- 

 inches. 



Llanerch is about a mile and a half above the town of St. Asaph, about 6 

 miles from the mouth of the river Lluyd, which falls with a rapid stream into 

 the Irish sea ; and, consequently, is several feet above its surface. 



May 26, between one and two in the afternoon, on the top of Snowdon, I 

 thrice repeated the experiment, and as often found the height of the mercury 

 26 inches 1. And being come down to Llanberris, at the foot of the hill, 

 about 6 that evening, I as often found it 29.4 inches. A little above this place 

 are the principal fountains of the river, that falls into the channel of Anglesey, 

 at Carnarvon, called anciently Segontium, whither we went the next day ; and 

 about 8 at evening, fouuil the mercury, by a triple experiment, to stand at 

 29.9 inches, very near the surface of the sea : when, at the same time, at 

 Llauercli, it v,;:s not above 29.7-L ; whence I conckule, that the difFcrmre of 

 the air's pressure on the sea and on the top of Snowdon, is rather more than 

 3 inches, 8 tenths. I could Lave wislied for one ol Mr. Hunt's portable baro- 

 meters ; which wil! certainly be accurate enough for taking the levels, for 

 bringing of v\ater from distant ])laces, ami certainly much less subjcci to error ; 

 there being a tenth of an inch for each 30 yards, which may bo divided into 



