The Congress of Aerostatics has been one of the most interesting of the series held at Paris during the Exposition. It was presided over by M. Janssen, Director of the Observatory of Meudon, in which the meetings were held. The different governments sent official delegates; those of the United States were Messrs. Chanute, Gallice, Langley, Marvin, Rotch, Poëy, and Zahm. The list of delegates included a great number of names prominent in aeronautic and scientific work, such as Aimé, Bereau, Bonaparte (Prince Roland), Bruce, Saint Victor, De Dion, Giampetro, De Fonvielle, Lieut. Hinterstoesser, Hammer, Count de la Valette, Morani, Richard, Santos-Dumont, Tissandier, Tzerseleff (Prince Dimitry), etc. The French army and marine were represented by a number of delegates. The principal address was delivered by M. Janssen, in which he reviews the progress already made in aerostatics and the results hoped for in the future. Since the last Congress, held at Paris in 1889, a considerable progress has been made in the different branches. In France and the leading nations the governments have taken up the subject, and its importance in military operations is becoming more clearly recognized. If it is considered that the armies are constantly increasing, as well as the range of the arms of artillery and infantry, a like extension of the theater of combat is to be predicted, and in consequence the use of balloons will become indispensable, and these will be provided with more powerful optical appliances. It must not be forgotten that balloons play an important part in indicating to the artillery the efficacy of its fire and the corrections to be given. If, on one hand, it is pleasing to record the progress which military aerostatics has accomplished in the hands of the skilled officers charged by their governments with the establishment and operation of these services, it must be acknowledged that great desiderata still exist. In fact, if it is possible to leave a besieged place almost with impunity, it is not the same for re-entering; it is to this second phase of the question that the subject of the direction of balloons is attached. Since 1889 the great problem of the dirigibility of balloons has occupied many workers, but it should be said that in spite of the very interesting attempts, the question has not made a decisive step. The experimenters are, however, still at work. M. Santos-Dumont is preparing for the competition for the Deutsche prize of $20,000, and Count Zeppelin is making a great effort with his balloon of 360 feet on Lake Constance. Although the question of dirigibility is the most important, it is also of the greatest interest to improve the aeronautic conditions, either as to remaining as long as possible in the air or to rise to a great height. In this order of facts may be cited the remarkable voyage of Count de Castillon de Saint-Victor from Paris to Sweden, where the balloon covered more than 800 miles, and that of Count de la Vaulx, who kept his balloon in the air for more than 30 hours without landing. M. Mallet has made with the same balloon a tour of France lasting eight days, landing in different places. As regards the altitude reached, the record has been made by M. Berson, of the Meteorological Institute of Berlin, who has risen several times to a height of 28,000 feet, exceeding the highest summits of the Himalayas; it is by the use of oxygen that M. Berson was able to support the rarefaction of the air at this great height. Scientific ascensions have made great progress in Germany owing to the initiative of the Society of Aerial Navigation of Berlin, which is sustained by the liberality of the Emperor. During the last five years the number of these ascensions has reached no less than seventy-five, and the results obtained have lately been discussed in the extensive treatise of Assmann, Berson, and Gross. But the heights attained by these balloons carrying observers are necessarily limited. Even with the use of oxygen, the observer must contend with the depression which surrounds him, and from which results an expansion of all the gases contained in the system, which, in spite of the respiratory reparation due to oxygen, may lead to death. M. Janssen then speaks of the scientists and aeronauts whose loss is to be regretted, among others Eugene Godard, originator of siege balloons, and from whom the author obtained excellent counsels at the time of leaving Paris the 2nd of December, 1870, during the siege with the balloon "Volta;" Hureau de Villeneuve, one of the founders of the Society of Aerial Navigation; Gaston Tissandier, Coxwell, and others. M. Janssen closes his address by a review of the advantages which would result from the mastery of the air and the effects this would have upon civilization.

The Congress was divided into four sections, and in each a number of interesting papers were read. The following is a list of the sections and some of the communications for each: Section 1. Aerostatics. Aimé; dirigible thermosphere. Angelot; new system of balloons. Dibos; signals from balloons at great distances. Giampetro; use of sails in direction of aerostats. Jaguaribe, new apparatus (velo-aerian). Regnard; ascensional propeller. Zahm; theory of balloon direction, etc. Section 2. Aviation. Ader; military aviation. Alexander; force of helices. Bretonnière; study of flying and aeroplanes. Canovetti; experiments on the resistance of air. Herard; new propeller. Mortureux; aerocycle with four wings. Rotch; use of kites at Blue Hill, United States. Roux; study of the flight of birds. Santi; aeroplanes, etc. Section 3. Instruments. Assmann; scientific aerial voyages. Batut; aerial photography from kites. Bouquet de la Grye; aerial telegraphy from balloons. Bruce; luminous balloons for military signals and exploration. Dibos; project of exploring voyage in Central Africa. Rotch; kite apparatus. Triboulet; method of triangulation by panoramic apparatus, etc. Section 4. Legislation. Formation of a scientific commission for the study of aerostatic patents. De Villiers; role of military aeronauts in the Egyptian campaign. Pesce; aeronautic and maritime rights, etc. A number of these papers, which are of great interest, will be reproduced in full or in abstract.

This report appeared in Scientific American, 84, March 2, 1901, page 130.