378 REPORT—1862, 
shades as in the other pair of thermometers. In the left-hand tube was 
placed the dry-bulb, and in the right-hand tube the wet-bulb thermometer. 
Towards the lower end of the left-hand tube there was an opening ; by means 
of the aspirator a current of air was drawn in at this aperture, then passed 
the dry-bulb in its upward passage into the small horizontal tube, and from 
thence into the right-hand tube, passing downwards over the wet-bulb, and 
away by a flexible tube into the aspirator, These instruments were made 
by Messrs. Negretti and Zambra. 
Regnault’s Condensing Hygrometer.—This instrument was made with two 
thermometers, as described by Regnault in the ‘ Annuaire Météorologique de 
la France’ for 1849, page 221, excepting that it was furnished with silver-gilt 
cups. The scale was of ivory, and the two thermometers were fixed in their 
cups by means of cork, for ready packing up. The instrument was made by 
Messrs. Negretti and Zambra. 
Daniell’s Hygrometer was of the usual construction, by Messrs. Negretti and 
Zambra, 
Exhausted Tubes for collecting Air—These tubes were partly constructed 
by Messrs. Negretti and Zambra, and partly by Mr, Casella. 
The thermometers employed in the observations were exceedingly sensitive ; 
the bulbs were long and cylindrical, being about #ths of an inch in length, 
and ;4,th of an inch in diameter. The graduations, extended to minus 40°, 
were all on ivory scales. These thermometers, on being removed from a room 
heated 20° above that of an adjoining apartment, acquired the temperature 
within half a degree in about 10 or 12 seconds; but in passing from a heated 
apartment to one of a lower temperature, it took more than double the time 
to approximate to within half a degree of the latter, They were so sensitive 
that scarcely any correction is required to be applied to them on account of 
sluggishness ; and this was found to be the case by the very near agreement 
in the temperatures at the same height in the ascending and descending 
curves, in those cases where there was reason to believe that there had been 
no change of temperature at the same height, within the interval between 
the two series of observations. 
§ 2. OpsERvING ARRANGEMENTS. 
One end of the car was occupied by Mr. Coxwell; near the other, in front 
of myself, was placed a board or table, the extremities of which rested on the 
sides of the car; upon this board were placed suitable framework to carry the 
several thermometers, hygrometers, magnet, aneroid barometer, &c.; a per- 
foration through it admitted the lower branch of the mercurial barometer to 
descend below, leaving the upper branch at a convenient height for observing. 
A watch was set to Greenwich time, and placed directly opposite to myself. 
The central space of the table was occupied by my note-book. The aspirator 
was fixed underneath the centre of the board, so as to be conveniently work- 
able by either my feet or hands. Holes were cut in the board to admit the 
passage of the flexible tubes, one of which passed to Regnault’s hygrometer, 
and the other to the place of the dry- and wet-bulb thermometers previously 
referred to, both the tubes being furnished with stopcocks. 
Circumstances of the Ascents, and General Observations. 
The ascents were all made by Mr. Coxwell’s large balloon,—three from 
Wolverhampton, four from the Crystal Palace, Sydenham, and one from 
