EXPLORATIONS OF THE UPPER ATMOSPHERE. 307 



This appears to indicate that the velocity of the wind increases with 

 the altitiTde. The distance traveled by the balloon was 430 kilometers 

 in four hours and forty -five minutes, which gives an average velocity of 

 90 kilometers an hour. 



IV.— INTERNATIONAL ASCENTS OF THE 14TH NOVEMBER, 1896. 



The International Conference of Meteorology, held in the month of 

 September, 1896, under the presidency of M. Mascart, having manifested 

 a desire to see the experiment tried of simultaneous ascents of several 

 balloons provided with registering apparatus, an agreement was entered 

 into by MM. Hermite and Besan^on and various forei^^u observers — 

 M. Hergesell, president of the international committee of scientific 

 aerostation; M. Assraann, chief of division in the Meteorologic Insti- 

 tute of Berlin; General Eykatcheff, at St. Petersburg, aud M. Erk, 

 at Munich. It was decided that simultaneous ascensions should be 

 made on the night of the 13th-14th ISovember, from the gas works of 

 La Villette, at Paris, from Strasburg, from Berlin, from Munich, and 

 from St. Petersburg. Many mounted balloons were also freighted to 

 start at about the same hour from different cities, and thus contribute 

 to the general result. 



The ascent from Paris took place, during magnificent weather, at 

 2.06 a. m. The air was calm, but saturated with moisture. The baro- 

 metric pressure was 761 millimeters aud the temperature 3° 0. The 

 ascensional force of the Aerophile was 248 kilograms, which gives the 

 gas a lifting force of about 800 grams per cubic meter.^ The total 

 weight of the material taken up was 45.5 kilograms, the only instru- 

 ments carried up being the baro thermograph, which we have already 

 described. 



The balloon disappeared in the night with extraordinary rapidity and 

 for three days we heard nothing further from it. Jt was thought that 

 it might have been lost at sea or in some distant forest, when a letter 

 came to Paris, informing MM. Hermite and Besangon that their appa- 

 ratus had fallen at break of day at Graide, in Belgian Luxemburg, and, 

 by a singular coincidence, less than a kilometer away from where we 



' The density of illuminating gas is very variable, and at the works of La Villette 

 its lifting force per cubic meter oscillates between 620 and 820 grams. It would 

 therefore be desirable to inflate the Aerophile with pure hydrogen, as the Germans 

 do with the Cirrus. But pure hydrogen is not found in France, and MM. Hermite 

 aud Besan^on, whp had asked the minister of war for permission to purchase the 

 quantity of gas necessary for inflation from the persons who furnish hydrogen to the 

 army, received no reply. We then offered to assist the two persevering physicists 

 in their attempt to avoid the difficulty and to purify — to decarburise, in brief — the 

 nauseous compound furnished to aeronauts by the Parisian gas company. The 

 apparatus is now completed, and if, as there is reason to hope, the experiment 

 demonstrates the justice of our theory, the Aerophile will be inflated with almost 

 pure hydrogen, purified by passing through a decarburator before l)eing stored in 

 the sphere of silk, and the ascensional force will be found to be increased by about 

 one-fourth. 



