TRANSACTIONS OF THE SECTIONS. 3Yr 
in the middle parts of the island it changed from south-easterly to 
south-westerly about those same hours—the change taking place about 
two hours sooner on the west side of the island than on the east side in 
the central parts, but much sooner in the northern parts than in the 
southern. ‘The barometer also fell sooner in the northern and western 
parts than in the southern and eastern. From these two circumstances 
he thinks it highly probable that this storm moved not exactly towards 
the east, but a little south of east, and if so, it would be similar to 
some storms which he had examined in the United States. 
The barometer was at its minimum at Cape Wrath, in the north-west 
corner of Scotland, two hours and a half sooner than at the Calf of 
Man, five hours sooner than at Edinburgh, and thirteen hours and a 
half sooner than at Thwaite, in Suffolk. Mr. Espy then stated that he 
had examined the data furnished by Col. Reid, of several hurricanes 
in the West Indies, and found conclusive evidence that the wind blew 
inwards to a central space in all these storms. Diagrams of two were 
exhibited: one on the 3rd of October, 1780, in which Savannah-la- 
Mar was destroyed. In that storm, at its very height, the wind at 
Savannah-la-Mar, on the south side of the island of Jamaica, was 
south,—and nearly opposite to that point, on the north side of the 
island, the wind was north-east, or nearly in an opposite direction, for 
two hours at the time of the greatest violence of the storm at both 
places. The other storm was on the 18th of August, 1837, off Char- 
leston, south-east. On that day, the ship Duke of Manchester had the 
centre of the storm passing over her, and, on the same day, the West 
Indian and the Rawlins, which were on the south-west of the Duke of 
Manchester, had the wind all day from 2 a.m. south-west, and at the 
same time the Cicero and the Yolof, on the north-east of the Duke of 
Manchester, had the wind north-east and east-north-east, the Yolof all 
day, till 8 p.m. 
Mr. Espy then stated that he had visited the tracks of eighteen tor- 
nadoes, and examined several of them with great care, and found that 
all the phenomena told one tale—-the inward motion of the air to the 
centre of the inverted cone of cloud as it passed along the surface of 
the earth. From all these facts he inferred that there is an inward 
motion of the air towards the centre of storms from all sides; and 
stated that this inference ought to be drawn from the well-known fact, 
that the barometer stands lower in the midst of a storm than it does 
all round its borders. 
Mr. Espy exhibited an instrument, which he called a Nephelescope, 
which enabled him to measure the expansion of air with great accuracy, 
and he found it to agree with calculations made on chemical principles. 
He then proceeded to give an outline of his theory, premising that the 
numbers he should introduce were not intended to be strictly accurate, 
and would be subject to many corrections,—one in particular, in which 
no notice had been taken of the specific heat of air under different 
pressures. The following are extracts. 
“When the air near the surface of the earth becomes more heated or 
more highly charged with aqueous vapour, which is only five-eighths 
