TRANSACTIONS OF SECTION Ay 415 
A minute mirror is mounted on a very small cylindrical steel staff which 
is capable of rotation in delicate jewelled bearings. A fibre is attached to 
the centre of a diaphragm, passes around a small pulley on the staff, and is 
kept taut by a spring. When a sound-wave impinges upon the diaphragm 
the mirror is given rotation proportional to the displacement of the 
diaphragm. The moving parts have a mass of less than 3 milligrams, 
and are so designed as to have a minimum moment of inertia. The radius 
of the pulley is 0°3 millimeter, and a moving photographic film is placed at 
such a distance that light reflected from the mirror to the film records the 
movements of the diaphragm magnified 2,000 times. 
The records exhibited showed: simple sine curves from tuning-forks, and 
the combination of these; the separate and combined curves from an organ- 
pipe and a whistle having a frequency of more than 3,000; the curves from 
a flute, and from a bell. The following records of spoken words are 
shown: one record of the words ‘sound-waves,’ one record of the words 
‘Karl Fischer,’ five different records of the word ‘fish,’ and four different 
records of the words ‘Lord Rayleigh.’ The quantitative analysis of such 
records is in progress. 
DEPARTMENT OF CosmicaL PHysics. 
1. The Highest Meteorological Observations in America. 
By Professor A. Lawrence Rotcu. 
Although numerous observations with ballons-sondes, extending to great 
heights above the interior of the American continent, were made by the 
author in 1904-7 at St. Louis,’ such data were not available in the eastern 
United States until last year, the maximum altitude at which the 
temperature was obtained, 7,040 metres, having been reached by kites flown 
from Mount Weather, in Virginia. 
By limiting the duration of the ascensions of the ballons-sondes, they 
were successfully used by the author at Pittsfield, Mass., about 150 miles 
from the Atlantic coast, in May and July, 1908. Three instruments of 
the four sent up were recovered, that on May 7 having an excellent record 
of temperature to a height of 17,700 metres, which exceeds by 650 metres the 
highest ascension at St. Louis. The warm stratum, described in the 
author’s previous paper, was penetrated further than ever before in 
America, the minimum temperature of —545° C. occurring at 12,500 
metres, whereas —45°6° was recorded 3,000 metres higher, the stratum above 
being nearly isothermal, as shown by the spring ascensions at St. Louis. 
The height of the inverting layer and the minimum temperature agreed 
approximately with the averages for May over the interior of this continent. 
Two other ascensions from Pittsfield to 6,100 and 9,700 metres respectively, 
although they did not reach the great inversion, showed the characteristic 
stratification of the atmosphere, with a rise of temperature in the lower 
clouds and an accelerated fall of temperature with increasing height. 
2. The Thermal Structure of the Atmosphere over the British Isles, 
July 27-29, 1908. By Dr. W. N. Saw, F.R.S. 
8. Results of Twenty-five Registering Balloon Ascents from Manchester 
during the period June 2, 7 p.M., to June 3, 7 p.m., 1909. By 
W. A. Harwoop, M.Sc. 
The ascents were made in connection with the work carried on at the 
Howard Estate Observatory on Glossop Moor. The balloons used were of 
thin rubber, filled with hydrogen, and had a free lift of about 300 gm., 
! Report, Dublin Meeting, 1908, p. 594, 
