March 3, 1905.] 



SCIENCE. 



335 



pressure required to balance the outward 

 radial tendency is equal to the pressure 

 due to the wind at the open end of the 

 tube. AVhen this condition is imposed in 

 the equation the value of k is obtained in 

 terms of temperature, barometric pressure 

 and velocity. The value is practically in- 

 dependent of V for velocities less than 100 

 miles per hour. 



Hie Temperature and Drift of the Air at 

 Great Heights above the American Con- 

 tinent, Obtained by Means of Registra- 

 tion Balloons. (Preliminary Report.) 

 A. Lawrence Rotch, Director of Blue 

 Hill IMeteorological Observatory. 

 Although the meteorological conditions 

 of the lower two or three miles of air have 

 been investigated by means of kites at Blue 

 Hill Observatory during the past ten years, 

 no observations have been made at greater 

 heights in this country. Through coopera- 

 tion with the management of the St. Louis 

 Exposition, the author obtained such ob- 

 servations by means of ballons-sondes ; 

 fourteen of these balloons carrying self- 

 recording instruments were despatched 

 from St. Louis and all were recovered with 

 ten records of barometric pressure and air 

 temperature. From the barometric rec- 

 ords the maximum height attained was 

 found to be about 51,000 feet, where the 

 temperature was 68° F. below zero on 

 September 23. At a height of about 45,500 

 feet (the maximum of the second series of 

 experiments) the temperature was —72° 

 F. on December 2, the lowest temperature, 

 —76°, occurring at a height of about 

 33,000 feet on November 26. The direc- 

 tion and velocity of the upper air currents 

 were indicated approximately by the places 

 and times at which the balloons fell. The 

 velocity twice exceeded 100 miles an hour 

 and all the balloons (excepting one which 

 did not rise out of the surface current) 

 drifted towards the east, in general diverg- 



ing from the areas of low barometric pres- 

 sure at the ground. 



An account of these experiments will 

 be published in full in the Annals of the 

 Harvard College Observatory, Vol. LVIII., 

 Part II. 



Optical Refraction in the Lower Atmos- 

 pheric Strata, as Affected by the 

 Meteorological Conditions. (Prelimi- 

 nary Report.) A. Lawrence Rotch, 

 Director of Blue Hill Meteorological Ob- 

 servatory. 



The variation in refraction has generally 

 been attributed to the differences in the 

 temperature of superposed strata of air, 

 but there have been few investigations 

 upon the effect of the daily changes in 

 meteorological conditions. Accordingly, 

 during two years, observations were made 

 three times a day with a precise level, on 

 the summit of Blue Hill, of the apparent 

 angular depression of a lighthouse in Bos- 

 ton harbor, fourteen miles distant and 

 550 feet below the hill, the temperatures 

 here and over the water being known. 

 Since the temperature of the air over the 

 ocean is more uniform than that over the 

 land, there is a large annual period in their 

 difference, but no relation between these 

 vertical gradients and the observed refrac- 

 tion is evident, nor do the monthly ex- 

 tremes appear to be connected Avith the 

 corresponding gradients of temperature. 

 This indicates that there are other con- 

 trolling influences and these are now being 

 sought. The investigation will be pub- 

 lished in Vol. LVIII., Part II., of the 

 Annals of Harvard College Observatory. 



Experimental Study of the Use of Wesson 

 Instruments for Ballistic Magnetic Test- 

 ing. Albert F. Ganz, Stevens Institute 

 of Technology. 



At various times it has been either 

 claimed or disputed that a damped gal- 

 vanometer in which the damping force is 



