An Account of Meteorological and Physical Observations in Eight Balloon Ascents, made, under the Auspices of the Committee of the British Association for the Advancement of Science at Manchester, by JAMES GLAISHER, F.R.S., at the request of the Committee, consisting of Colonel Sykes, Professor Airy, Lord Wrottesley, Sir D. Brewster, Sir J. Herschel, Dr. Lloyd, Admiral FitzRoy, Dr. Lee, Dr. Robinson, Mr. Gassiot, Mr. Glaisher, Dr. Tyndall, Mr. Fairbairn, and Dr. W. A. Miller.

THE objects to which the Committee resolved to devote their principal attention were the determination of the temperature and hygrometric condition of the air at different elevations above the earth's surface. In addition to which, several other secondary objects were to be carried out if possible, as follows::

§ 1. OBJECTS OF THE EXPERIMENTS.

The primary objects were—

The determination of the temperature of the air, and its hygrometrical states, at different elevations, as high as possible.

The secondary objects were

To determine the temperature of the dew-point by Daniell's dew-point hygrometer, by Regnault's condensing hygrometer, and by dry- and wet-bulb thermometers as ordinarily used, as well as when under the influence of the aspirator; so that considerable volumes of air were made to pass over both their bulbs, at different elevations, as high as possible, but particularly up to those heights where man may be resident, or where troops may be located, as in the high lands and plains in India, with the view of ascertaining what confidence may be placed in the use of the dry- and wet-bulb thermometers at those elevations, by comparison with the results as found from them, and with those found directly by Daniell's and Regnault's hygrometers, and to compare the results as found from the two hygrometers together.

To compare the readings of an aneroid barometer with those of a mercurial barometer up to 5 miles.

To determine the electrical state of the air.

To determine the oxygenic condition of the atmosphere by means of ozone

papers.

To determine the time of vibration of a magnet on the earth, and at different distances from it.

To collect air at different elevations.

To note the height and kind of clouds, their density and thickness.

To determine the rate and direction of different currents in the atmosphere,

if possible.

To make observations on sound.

To note atmospherical phenomena in general, and to make general observations.

Instruments and Apparatus.

The instruments used were mercurial and aneroid barometers; dry- and wet-bulb thermometers; Daniell's dew-point hygrometer; Regnault's condensing hygrometer; maximum and minimum thermometers; a magnet for

horizontal vibration; hermetically sealed glass tubes from which air had been exhausted; ozone papers; and an electrometer lent by Prof. W. Thomson of Glasgow.

Barometers.-The mercurial barometer employed in all the ascents was a Gay-Lussac's siphon barometer by Mr. P. Adie, and is one of those used by Mr. Welsh in the year 1852 in his experiments. The inner diameter of its tube is 0.25 inch. The graduations were made on a brass scale, from its middle point upwards and downwards; each division was about 0.05 inch in length, representing twice that value, so that an observation of either the lower or upper surface of the mercury would give the approximate length of the column of mercury.

The readings of the upper end were alone taken, and the corrections applicable to this end have been applied to all observations.

The barometer was furnished with its own thermometer, whose bulb was immersed in a tube of mercury of the same diameter as that of the barometer. This instrument sometimes read more than 20° in excess of that of the sensitive air-thermometer.

The aneroid barometers were made by Messrs. Negretti and Zambra; one was graduated to 13 inches, and the other to 5 inches-the latter instrument having been used in the ascents on August 18 and September 5, and the former on July 17. In consequence of a difference of reading between the aneroid and mercurial barometers on July 17 (and as both instruments were broken, it was impossible to say which was in error), and as the correctness of the siphon barometer at low readings is dependent upon the evenness of the tube, another barometer was used in addition on September 5, made by and at the suggestion of Messrs. Negretti and Zambra, as follows:

:

A tube 6 feet in length was filled with mercury and boiled throughout its whole length; a glass cistern was blown on the bottom of the tube, and bent upwards in the form of a siphon; a stopcock was placed between the tube and cistern, and whilst the mercury filled the entire tube, a mark was made on the cistern, at the level of the mercury in it, for zero; the stopcock was then gradually opened, and the mercury allowed to descend one or more inches. The rise which consequently took place in the cistern was carefully marked on the same side as "O" (zero); the stopcock was again opened and the same operation was repeated until 30 inches of mercury had left the upper part of the tube, and the successive levels of the mercury in the cistern had been accurately marked.

In finally making the barometer, the upper portion only of the tube was used; the cistern which had been at the end of the lower portion was removed and joined on the upper; and in graduating the scale of the barometer, the rise which took place in the cistern at every inch was deducted, and the scale reduced in its entire length, by the exact amount of the rise of the mercury in the cistern. This instrument was therefore probably as accurate at low readings as at high.

Dry- and Wet-Bulb Thermometers.-Two pairs of dry- and wet-bulb thermometers were employed; one pair as ordinarily used, their bulbs being protected from the direct rays of the sun by a double highly polished silver shade, in the form of a frustum of a cone, open at top and bottom. cistern was fixed near to them, from which water was conveyed to the wetbulb thermometer.

A

The bulbs of the second pair of dry- and wet-bulb thermometers were enclosed in two silver tubes placed side by side, and connected together by a cross tube joining their upper ends, and over both were placed double 1862. 2 c

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, andth 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. OBSERVING 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 perforation 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 workable 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

Mill Hill, near Hendon, where the balloon had fallen the evening previous, and had been anchored during the night.

Ascent from Wolverhampton, July 17.-The balloon was inflated at the Stafford Road Gas-works, Wolverhampton, with carburetted gas, most carefully prepared by the Engineer, Mr. Thomas Proud, and frequently kept a long time for our use, the Directors of the Gas Company having most liberally, to their great inconvenience, placed a gasometer at our disposal for as long a time as we needed it. To the Directors of the Company and to Mr. Proud our best thanks are due; for on all occasions they showed the utmost anxiety to contribute to the success of the experiments, in which Mr. Joseph Walker, Mr. Joseph Cooper, and Mr. Proud took great interest.

The weather previously had been bad for a long time, and the ascent had been delayed some days in consequence; the wind was still blowing strongly from the West; and considerable difficulty was experienced in the preliminary arrangements, and no instrument was placed in its position before starting. The ascent took place at 9h 43m A.M.; at once the balloon was quiescent. A height of 3800 feet was reached before an observation could be taken; at 4000 feet clouds were entered, which were left at 8000 feet. The temperature of the air fell to 33°, and a height exceeding 10,000 feet had been passed before all the instruments were in working order. The sky was then noticed to be of a deep-blue colour, without a cloud of any kind upon its surface.

At starting, the temperature of the air was 59°, and dew-point 55°; at 4000 fect it was 45°, dew-point 33°, and descended to 26° at 10,000 feet, dewpoint 19°, and then there was no variation of temperature between this height and 13,000 feet. During the time of passing through this space, both Mr. Coxwell and myself put on additional clothing, feeling certain that we should experience a temperature below zero before we reached 5 miles high; but to my surprise, at the height of 15,500 feet, the temperature, as shown by all the sensitive instruments, was 31°, dew-point 25°; and at each successive reading, up to 19,500 feet, the temperature increased, and was here 42°, dew-point 24°. We had both thrown off all extra clothing. Within two minutes after this time, when we had fallen somewhat, the temperature again began to decrease, with extraordinary rapidity, and was 16°, or 27° less than it was 26 minutes before: at this time a height of 5 miles had been reached, at about 11 A.M.

When the balloon had attained a height of 4 miles, I wished to descend for one or two miles and then to re-ascend; but Mr. Coxwell, who had been watching its progress with reference to the clouds below, felt certain that we were too near the Wash; prudence therefore caused us to abandon the attempt.

Our descent began a little after 11 A.M., Mr. Coxwell experiencing considerable uneasiness at our too close vicinity to the Wash; we came down quickly, passing from a height of 16,300 feet to one of 12,400 feet between 11h 38m and 11h 39m; dipping into a dense cloud at this elevation, which proved to be no less than 8000 feet in thickness, and whilst passing through this the balloon was invisible from the car. Mr. Coxwell had reserved a large amount of ballast, which he discharged as quickly as possible to check the rapidity of the descent; but notwithstanding all his exertions, as we collected weight by the condensation of that immense amount of vapour through which we were passing, the descent was necessarily very rapid, and we came to the earth with a very considerable shock, which broke nearly all the instruments. All the sand was discharged when we were at a considerable elevation; the amount we had at our disposal at the height of 5 miles was

fully 500 lbs.; this seemed to be more than ample, and, when compared with that retained by Gay-Lussac, viz. 33 lbs., and by Rush and Green, when the barometer reading was 11 inches, viz. 70 lbs., seemed indeed to be more than we could possibly need, yet it proved to be insufficient.

The descent took place at Langham, near Oakham in Rutlandshire, in a meadow near the residence of Mr. E. G. Baker, from whom we received the utmost attention.

Ascent from the Crystal Palace, July 30.-A table was fixed to the side of the car, partly within and partly without. The instruments were placed on a framework, fixed to the part of the table outside, so as to be beyond the influence of the occupants of the car; my note-book, watch, and aneroid barometer rested on the inner part of the table. The air was in gentle motion from the south-west, enabling the instruments to be made ready for observation before starting, and at 4h 40m P.M. the balloon left the earth.

The temperature declined instantly. Observations were taken every minute or half-minute from the time of ascent, to as near as possible the time of descent.

The readings of one barometer were kindly made by Mr. W. F. Ingelow, and he also assisted me in observing the first appearance of dew on the hygrometer.

A height of 7000 feet was reached at about 6 o'clock, and the descent began about a quarter past 6; it was rather rapid, but quite under control, and we reached the earth at the village of Singlewell, near Gravesend, at 6h 30m.

Ascent from Wolverhampton, August 18.-The weather on this day was favourable; there was but little wind, and that blowing from the N.E. By noon the balloon was nearly inflated, and as it merely swayed in a light wind, all the instruments were fixed before starting, and at 1h 2m 38s P.M. Mr. Coxwell pulled the spring-catch; for a moment the balloon remained motionless, and then rose steadily almost perpendicularly: this ascent was all that could be desired. In about 10 minutes we passed through a fine cumulus cloud, and then emerged into a clear space with a beautiful blue sky dotted over with cirrus clouds above. When at the height of nearly 12,000 feet, with the temperature of 38°, or 30° less than on the ground, and dew-point 26°, Mr. Coxwell discharged gas, and we descended to a little above 3000 feet at 1h 48m; a very gradual ascent then took place till 2h 30m, when a height of about 24,000 feet was obtained; and here a consultation took place as to the prudence of discharging more ballast or retaining it, so as to ensure a safe descent; ultimately it was determined not to go higher, as some clouds, whose thickness we could not tell, had to be passed through. The descent began soon after, and we reached the earth a little after 3 o'clock at Solihull, about 7 miles from Birmingham.

Ascent from the Crystal Palace, August 20.-The air was almost calm, the instruments were all fixed before starting, and the balloon left the Crystal Palace at 6h 26 P.M., the temperature at the time being 66°, dew-point 54°. By 6h 35m we were half a mile high, the temperature being 56°. At 6h 37m the height of three-quarters of a mile was attained, and the air was so tranquil that we were still over the Palace. At 6h 43m, when at the height of nearly a mile, a thick mist or thin cloud was entered, the earth being just visible. The temperature at this time was 50°, dew-point 46°; this elevation and temperature were maintained for about five minutes, and we then descended 200 or 300 feet. Kennington Oval was in sight. At 7 9m St. Mark's Church, Kennington, was exactly underneath us. We were now about a