810 ABBOTT LAWRENCE ROTCH. 



of the most complete investigations of the kind ever undertaken. The 

 first series of measurements in America of the height and velocity of 

 clouds, by trigonometrical and other methods, was made at BUie 

 Hill in 1890-91. These measurements were repeated in 1896-97, 

 as a part of an international sj^stem. 



It was at Blue Hill that the modern methods of sounding the air by 

 means of self-recording instruments lifted by kites were first developed 

 and effectively put into practise (1894), methods which have now been 

 adopted by meteorological services and scientific expeditions in all 

 parts of the world. The use of cellular kites flown with steel wire and 

 controlled by a power windlass originated at Blue Hill. Grants for 

 carrying on this kite work were obtained from the Hodgkins Fund. 

 The success of this exploration of the free air at Blue Hill led, more than 

 anything else, to the establishment of the Observatoire de la Meteoro- 

 logie dynamique at Trappes, under the direction of M. Leon Teisserenc 

 de Bort, and of the Aeronautisches Ohservatorium of the Royal Meteoro- 

 logical Institute, near Berlin, under Professor Richard Assmann. 



It was Rotch who, in 1901, during a voyage across the Atlantic, 

 first obtained meteorological observations by means of kites flown 

 from the deck of a moving steamer, thus indicating the feasibility of a 

 new way of securing information concerning the conditions of the 

 free air over oceans and lakes. It was Rotch who, in 1904, secured 

 the first meteorological observations by means of sounding balloons 

 from heiglits of 5 to 10 miles over the American continent, and who, 

 in 1909, made the first trigonometrical measurements of the flight of 

 pilot balloons in the United States. In 1905-06 he joined his col- 

 league, Teisserenc de Bort, in fitting out and taking part in an expe- 

 dition to explore the tropical atmosphere over the Atlantic Ocean by 

 means of kites and pilot balloons, an undertaking which resulted in 

 the collection of important data regarding the temperatures and 

 movements of the upper air, and especially concerning the existence 

 of the anti-trades. But Rotch was not content with merely sending 

 up kites and balloons. His enthusiasm in the study of the free air, 

 and his desire to visit the mountain observatories of the world, led 

 him to become a mountain climber of no mean ability. He ascended 

 to the summit of Mont Blanc at least five times, and in South 

 America and elsewhere he himself made meteorological observations 

 at considerable altitudes on mountains, and carefully observed the 

 physiological effects of the diminished pressure. He also took part 

 in several balloon ascents, taking important observations during 

 these trips, notably on that of October 24, 1891, starting from Berlin, 



