ON FIVE BALLOON ASCENTS IN 1863. 433 
height of 2800 feet we emerged from clouds and saw a stratum of darker cloud 
above; we then descended to 800 feet over the West India Docks, and saw 
rain falling heavily upon the earth. None was falling upon the balloon; that 
which we saw, therefore, had its origin within 800 feet of the ground; we 
ascended again, and this time passed upwards through fog 1400 feet in thick- 
ness. At 3300 feet we passed out of cloud, and again saw the dark stratum 
at a distance above ; clouds obscured the earth below. On descending, at 
2700 feet we entered a dry fog, but it became wetting 100 feet lower down. 
After passing through 600 feet the clouds became more and more wetting, 
and below were intensely black. At 5" 28™ we were about 70Q feet high, or 
about 500 feet above Epping Forest, and heard the noise of the rain pattering 
upon the trees. Again we ascended to 2000 feet, and then descended, passing 
into squalls of rain and wind at the height of 500 feet, with rain-drops in- 
creasing in size as we descended, till they were as large as a fourpenny piece, 
on reaching the ground being of the same size as when we left it. On de- 
scending we found rain had been falling heavily all the time we were in the 
air. 
§ 3. Description oF tHu TABLE OF OBSERVATIONS. 
All the meteorological observations taken during the ascents are contained 
in Table I. 
Column 1 contains the times at which the observations were made. Column 
2 contains observations of the siphon barometer corrected for temperature and 
index error. Column 3 contains the readings of the thermometer attached 
to the barometer. Column 4 contains the readings of an aneroid barometer. 
Column 5 contains the height above the level of the sea, as deduced from the 
barometric observations in column 2, by the formula of Baily, checked at in- 
tervals by that of Laplace, which is as follows ;— 
_1(% 2 t+¢—64 anges 2+52251 
where Z is the height required, and h, h’, ¢ and?t' the height of the barometer 
corrected for temperature, and the temperature of the air at the lower and 
upper stations respectively, L the latitude. The temperature of the air for the 
position of the balloon has been derived from the readings in column 10, 
Columns 6 to 9 contain the observations with the dry- and wet-bulb ther- 
mometers free, and the deduced dew-point. Column 10 contains the readings 
of Negretti and Zambra’s gridiron thermometer. Columns 11 to 14 contain 
the observations with the dry- and wet-bulb thermometers aspirated, and the 
deduced dew-point. Columns 15 and 16 contain the direct dew-point obser- 
vations with Daniell’s and Regnault’s hygrometers. When numbers are 
entered in columns 15 and 16 with “no dew” affixed to them, it is meant 
that the temperature of the hygrometer has been lowered to the degree stated, 
but that no dew has been deposited. 
The Astronomer Royal at the Royal Observatory, Greenwich, had meteo- 
rological observations taken every 10 minutes on all the days of ascent, and 
Dr. Lee had observations made at Wolverton by his assistant, Mr. 8. Horton, 
With instruments furnished and adjusted by Mr. Negretti, on June 26. 
In calculating the height of the balloon, the observations of Greenwich have 
been employed for March 31, April 18, July 11, and July 21; and those of 
Wolverton for June 26. 
The height of Greenwich above the mean sea-level=159 feet. 
The height of Wolverton above the mean sea-level =300 feet, 
1863, 2F 
