NOVEMBEE 21, 1919] 



SCIENCE 



483 



find the velocity at any subsequent time, by 

 adding the vector gi vertically downward to 

 the original vector velocity. The second 

 statement assumes, so far as I can see, a 

 knowledge of one of the quantities we need 

 to calculate. I should very much like to see 

 Dr. Hering's " applied " mathematics applied 

 to this simple problem. So far as I can see, 

 though the first statement simplifies the 

 mathematics, the second abolishes it. 



Scientific terminology is like a sharp knife 

 used for the dissection of a problem, and un- 

 equaled for its intended purpose. It is an 

 odd coincidence that the very number of 

 Science which contains Dr. Hering's letter 

 contains also an address by Dr. Gray of Edin- 

 burgh, in which the sharpness of this par- 

 ticular knife, the term acceleration in its 

 strict sense, is specially noted. Dr. Hering's 

 proposal is as if one should say, "I find your 

 razor good for sharpening pencils, please 

 shave with something else." 



Surely the ends, neither of science nor 

 engineering will be furthered by any such 

 change as Dr. Hering recommends. The 

 question is not one of simplified mathematics, 

 but of clearness of thought. 



C. M. Sparrow 



EoDss Physical Laboratory, 

 University of Virginia, 



NOTES ON METEOROLOGY AND 

 CLIMATOLOGY 



AEROLOGICAL work — WINDS 



After the signing of the armistice had 

 liberated much information that had been 

 held as confidential, it became possible to 

 assemble a group of papers on aerological 

 work describing the pilot balloon methods 

 used by the Weather Bureau, Signal Corps, 

 and N'avy for observing winds at various 

 levels, and presenting the results of various 

 lines of research.^ The use of thousands of 

 two-theodolite pilot balloon runs established 

 an empirical formula for the ascensional rate 



lifo. Weather Bev., April, 1919, Vol. 47, pp. 

 205-231. Separates of these are still available: 

 apply to Chief, TJ. S. "Weather Bureau, Washing- 

 ton, D. C. 



of pilot balloons which tallied remarkably 

 well with the formula derived from theoret- 

 ical considerations. This formula is 



V = 71(Z/W)5/8 = n{PIL^)-™, 

 in which V represents velocity, I the actual 

 lifting power of the balloon ("free-lift"), 

 i. e., the weight it will support, and L the 

 total lift (free-lift plus weight of balloon). 

 Surprising as it is, pilot balloons ascend at a 

 nearly constant rate, once they are above the 

 more or less turbulent surface layer of air. 

 Thus, single theodolite observations of angu- 

 lar altitude and azimuth of a balloon once a 

 minute, when used in conjunction with the 

 computed ascensional rate will yield reliable 

 information as to the actual positions of the 

 balloon, and, therefore, of the direction and 

 velocities of the wind at all levels from the 

 surface to the height at which it becomes lost 

 to view. At the Aberdeen Proving Ground, 

 temperatures for computing the densities of 

 the air in the several altitude zones have been 

 obtained by daily airplane ascents to a height 

 of 10,000 feet. The score of pilot balloon 

 stations in the United States east of the 

 Rockies telegraph free-air wind data to the 

 Weather Bureau in Washington twice daily, 

 where they are used not only for aeronautical 

 forecasting, but also as an auxiliary in 

 making surface weather forecasts. 



Meteorological kite flights are now being 

 made at six stations daily (except when winds 

 are light) for recording winds, relatively 

 humidities, and temperatures aloft. The re- 

 sults are telegraphed to Washington daily, 

 and later are published in Monthly Weather 

 Review Supplements, where they become 

 available for detailed investigation." 



The movements of dust, smoke and clouds 

 are useful as well as balloons and kites for 

 determining the movements of the free air. 

 Dustfalls which occasionally occur in the 

 northeastern United States have been traced 



2 See, for instance, V. E. Jakl, ' ' Some observa- 

 tions on temperatures and winds at moderate ele- 

 vations above the ground," Mo. Weather Bev., 

 June, 1919, pp. 367-373. Separates of these are 

 still available: apply to Chief, U. S. Weather 

 Bureau, Washington, D. C. 



