532 



SCIENCE. 



[N. S. Vol. VIII. No. 199. 



Temperature and Vapor Gradients in the Atmos- 

 phere. By Professor F. H. Bigelow, 

 Washington, D. C. 



Tivo Neil} Forms of Apparatus for Measuring 

 the Acceleration of Gravity. By Professor 

 R. S. Woodward. 



The author suggested the use of the vibra- 

 tions of a weight hung from a helical spring. 

 Professor T. C. Mendenhall suggested the 

 use of a flat ring as a pendulum, the only 

 linear measiirement required being the 

 external diameter of the ring. 



The Structure of Cyclones and Anticyclones. By 

 Professor F. H. Bigelow. 



The Gravitation Constant and the Mean Density 

 of the Earth. By Professor R. S. Wood- 

 ward. 

 Professor Woodward pointed out a new 



form of the relation between these two 



quantities. 



On the Relative Brightness of Pigments by 

 Oblique Vision. By Professor F. P. 

 Whitman, Cleveland, Ohio. 

 Professor Whitman used the flicker pho- 

 tometer and found that the brightness at 

 the red end of the spectrum decreases as 

 the vision becomes more oblique, while the 

 opposite is true (but to a less extent) at the 

 violet end. The brightness of yellow-green 

 is nearly independent of the angle. 



A New Instrument for the Measurement of the 

 Intensity of Sound. By Professor A. G. 

 Webster and Mr. B. F. Sharpe. 

 The method consists in measuring, by 

 means of an interferometer, the amplitude 

 of vibration of a thin glass plate. The in- 

 terference fringes are photographed on a re- 

 volving drum. The constants of the in- 

 strument can be experimentally determined 

 and the intensity of the sound can be cal- 

 culated in absolute terms. 



Exhibit of an Automatic Mercurial Air Pump 

 designed by Professor E. W. Morley. By 

 Professor D. C. Miller. 



The peculiar advantages of the pump are 

 that it need not be situated near the auto- 

 matic controller, and that the mercury does 

 not come in contact with rubber. It can 

 be actuated with a water pressure of 20 

 pounds per square inch and can produce a 

 vacuum of 1-500,000,000 of an atmosphere. 



An Apparatus for demonstrating in Alternating 

 Currents the Change of Phase due to either 

 Inductance or Capacity. By Professor 

 Sidney T. Moreland, Lexington, Va. 



An Apparatus for determining Coefficients of 

 Induction. By Professor Sidney T. 

 Moreland. 



This apparatus consists of two coils at 

 right angles, producing a rotating magnetic 

 field when alternating currents of diiierent 

 phase are sent through the two coils. A 

 copper cylinder is suspended in this rota- 

 ting field and indicates the phase relations 

 of the two currents. 



An Improved Method for rating Tuning Forks. 



By J. 0. Reed, Ph.D., Ann Arbor, Mich. 



The method is a modification of that 

 used by Professor Michelson, but instead of 

 using an electric spark Dr. Reed employs 

 the flash of light from a mirror rotated by 

 a secondary pendulum, which is ''in turn 

 compared with the standard clock. 



A Neiu Chronograph and a Means of Rating 

 Tuning Forks. By Professor A. G. Web- 

 ster. 

 The chronograph is actuated by a small 



motor regulated by a tuning fork. 



A Geometrical Method for Investigating Diffrac- 

 tion by a Circular Aperture. By Profes- 

 sor A. G. Webster. 



Professor Webster obtains a kind of 

 'racket' Cornu's spiral for this case of dif- 

 fraction, that is a spiral having Cusps. 



Study of Elastic Fatigue by the Time Variation 

 of the Logarithmic Decrement. By Profes- 

 sor J. O. Thompson. 



