ON EIGHT BALLOON ASCENTS IN 1862. 387 
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. 
Many observers in different parts of the country made observations at short 
intervals for several hours together, on several days of which notice had been 
given them that the ascent would take place, but, in consequence of the fre- 
quent delays owing to bad weather, their observations were not available, 
and it was found impossible to give notice with any certainty of the days of 
ascents. 
A good many observers did, however, take a few observations in different 
parts of the country on the days of the several ascents. The Astronomer 
Royal at the Royal Observatory, Greenwich, had observations taken every 10 
minutes on all the days of ascent, and Lord Wrottesley always arranged to 
have observations made at Wrottesley by Mr. Hough, on those days when the 
ascent took place from Wolverhampton. In calculating the height of the 
balloon, the observations of Wrottesley have been employed for July 17, 
August 18, and September 5; and those of the Royal Observatory, Greenwich, 
haye been used for July 30, August 20, August 21, Sept. 1, and Sept. 8. 
The height of Greenwich above the mean sea-level =159 feet. 
The height of Wrottesley above the mean sea-level=531 feet. 
