72 REPORTS ON THE STATE OF SCIENCE. 
results of the observations. The results obtained from manned balloons 
were arranged and discussed very fully and systematically ten years ago 
by the German meteorologists, Von Bezold, Assmann, Berson, and Siiring ; ! 
but the discussion of the much more numerous results obtained with 
kites and registering balloons has been devoted to isolated ascents or to 
sag points, frequently imperfectly treated owing to the gaps and to 
the difficulty of dealing single-handed with a mass of undigested material. 
At the same time very much valuable knowledge has been acquired, and 
the meteorologist of to-day is in consequence much better equipped in 
many respects for attacking the problems to which his predecessors could 
bring only the ingenuity of speculation and of theory, although his work 
may be more difficult and less entertaining than theirs. 
By the use of kites a fairly complete knowledge has been obtained of 
the variation in the meteorological elements up to a height of 2 km. 
Registering balloons have furnished information regarding the distribution 
of temperature up to a height of 15-20km. But the comparative absence 
of arrangement of the observations in a form suitable for discussion has 
necessitated a considerable amount of labour in extracting from the 
observations the information they contained. It has therefore been im- 
possible to deal with all the branches of investigation, and the discussion 
of the observations of humidity, of the constitution and formation of 
clouds and fogs, and of the electrical state of the free atmosphere has not 
been included. The Report deals with the instruments and the methods 
of investigation and with the results for temperature and for wind. 
II. Historical Summary. 
Free Manned Balloons.?—The scientific investigation of the conditions 
of the upper atmosphere was begun about the middle of the eighteenth 
century by Bouguer, a French Academician, during a geodetic expedition 
to Peru. He fixed the height of the freezing-point in various latitudes 
by means of observations on the slopes of mountains. The first scientific 
manned balloon ascent was made by Jeffries, November 30, 1784, from 
London. The balloon-car contained a thermometer, barometer, hygro- 
meter, electrometer, mariner’s compass, and bottles filled with water for 
obtaining samples of air. The rate of fall of temperature was found to 
be 1° F. per 360 feet. No change of electrical conditions was indicated. 
Samples of air were sent to the Royal Society, but were apparently not 
analysed ; a paper on the results was read before the Society, January 
1786. The observations of Jeffries compare favourably with those 
made until the adoption of aspirated instruments. Some time then 
elapsed before the next ascent for purely scientific purposes was made. 
In 1803-04 Robertson, a Belgian physicist, made three ascents from Ham- 
burg and St. Petersburg. The third was made under the auspices of the 
Russian Academy, which proposed to examine the change in the rate of 
evaporation of fluids, change of magnetic force and magnetic inclination, 
and the increase of solar heat with increase of height. The Paris Academy 
of Sciences took up the investigation in the same year, and Biot and Gay- 
Lussac together (August 24, 1804), and later Gay-Lussac alone (Septem- 
ber 16, 1804), made ascents from Paris to verify Robertson’s St. Peters- 
burg results, which indicated that the magnetic force diminished with 
1 Wissenschaftliche Luftfahrten, 1899. 
? A good general account of the ascents made before 1870 is given in Travels in 
the Air, by Glaisher, Flammarion, de Fonvielle, and Tissandier. 
