REPORT OF THE SECRETARY. 15 



physical properties of carbon of the remarkable absorption of gases 

 at low temperatures is to be investigated, and two methods of deter- 

 mining the specific heat of gases have been perfected. The investiga- 

 tion of the properties of matter at the temperature of liquid hydrogen 

 will also be continued and the results recorded. 



STUDY OP THE UPPER ATMOSPHERE. 



The meteorological experiments of Mr. A. Lawrence Rotch with 

 registering balloons, conducted from St. Louis as the starting point, 

 have been again aided by a grant from the Hodgkins fund. Before 

 the close of similar experiments by Mr. Rotch from the same point 

 in 1906, the extreme height of nearly 10 miles was attained, and a 

 temperature of — 76° F. was once recorded somewhat below 7 miles. 



This final series of ascensions aided by the Institution is intended 

 to supply data for the season of the year in which observations of 

 the upper air have heretofore been the least frequent, and it is hoped 

 that the endeavor to ascertain the annual variation of temperature 

 at great heights in the free air above the American continent will 

 thus be materially furthered. 



A summary of the results of the meteorological research conducted 

 by Mr. S. P. Fergusson, mentioned in the previous Report as having 

 been aided by a moderate grant from the Hodgkins fund of the 

 Institution, has been submitted. 



Stations for these experiments were established on the summit of 

 Mount Washington, 1,916 meters above sea level, and at Twin 

 Mountain, 1,500 meters lower and 15 miles distant. Louvred shelters 

 were built for the proper exposure and protection of the instruments 

 at these stations, and the anemometer was erected on the old Tip Top 

 House, the highest point on the summit of Mount Washington. 

 Records were made at the stations, as nearly as possible continuous, 

 of pressure, temperature, humidity, and wind velocity, while the 

 meteorographs recording the same elements were sustained by kites 

 in the free air for as long a time as possible during the research. 

 Observations of the formation of clouds on the mountain and in the 

 free air were also made. 



While the apparatus used in this research was the same in principle 

 as that heretofore employed, it is hoped that certain devices which 

 were suggested by the conditions, and successfully adopted, will 

 prove advantageous* in later experiments. The time available for 

 this research was necessarily limited, but the kites on several different 

 occasions carried the meteorograph sufficiently high for comparison 

 with the records obtained on Mount Washington. On the 6th of 

 September the instrument was kept at approximately the same height 

 in the free air and on the summit of Mount Washington for eight 

 hours between noon and 10 o'clock p. m. 



