34^J 



SCIENCE. 



[Vol. XVII. No. 437 



Williams, Messrs. A. E. Bibbins, F. P. King, E. P. Kohler P. R. 

 Moale, R. M. Parks. Jun., D. H. Roberts, M. J. Vea. aiicl D. B. 

 Pope, of the Johns Hopkins University ; President Henry E. Al- 

 vord of the Maryland Agricultural College; Messrs. W. H. Holmes, 

 N. H. Darton, C. D. White, and G. D. Harris, of the United States 

 Geological Survey; Br. E. Lewis Sturtevant, late director of the 

 New Yei-k Agricultural Experiment Station ; Professor Frank D. 

 Adams of McGill College, Montreal; and Mr. G. L. Collie of Har- 

 vard University; while President D. C. Gilman and Dr. H. M. 

 Hurd, as guests of the expedition, accompanied the party the first 

 day as far as Annapolis The expedition started from Baltimore at 

 noon of April 23, and reached Washington, where the party was 

 disbanded, at noon of April 30. Four lines of investigation were 

 proposed, namely : (1) study of the oyster; (2) study of the geo- 

 logical formations ; (3) study of the soils ; (4) study of the Indian 

 remains. By reason of the illness of Mr. A E. Bibbins, which 

 necessitated his return to Baltimore, work upon the oyster, of 

 which he had charge, had unfortunately to be abandoned, although 

 indications of good results were shown during the day or two he 

 was with the party. The geological work, under the direction of 

 Mr. Clark, assisted by Mr. N. H. Darton, was participated in by 

 the larger number present; the agricultural investigations were 

 conducted by Professor Milton Whitney; and Professor W. H. 

 Holmes of the Smithsonian Institution examined the area for evi- 

 dence of Indian occupation. 



LETTERS TO THE EDITOR. 



*#* Correspondents are requested to be as brief as possible. The writer's name 

 is in all cases reqnired as proof of good faith. 



On request, twenty copies of the number containing his communication will 

 1)6 furnished free to any correspondent. 



Eddies in the Atmosphere. 



During last December there was published a paper by Professor 

 Bezold -'On the Theory of Cyclones" (Sttzungsberichte der 

 koniglieh preussischen Academy der Wissenschaften zu Berlin). 

 This exhaustive setting forth of theories by the director of the 

 German meteorological bureau is of the highest interest, and de- 

 mands notice from this side of the ocean. Professor Bezold says: 

 -" If one has attentively followed meteorologic literature for late 

 _years, so can he not fail to note that in the fundamental principles 

 of air motions, little by little, a powerful revolution has taken 

 place." Our author then gives a summary of the views that have 

 arisen from time to time, especially regarding the relations be- 

 tween the general atmospheric circulation between the equator 

 and poles, and the oocuri-ence of storms or eddies in this circula- 

 tion. He then gives a theoretic discussion of a particular cyclonic 

 -circulation, stationary, and having the wind directions parallel to 

 the isobars. In this he finds that the whirl which occurs at the 

 ■earth's surface extends only a short distance vertically, though he 

 does not intimate whether this height should be 2,000, 10,000, or 

 20,000 feet. He also finds that if this whirl is exceedingly rapid, 

 as one approaches the axis, a centrifugal effect is induced, and 

 there results an '-air- thinning " at the centre; moreover, there 

 would be no tendency for air to rush to the centre, and hence 

 there would be no uprush of air there. This is certainly a most 

 stai'tling conclusion, and agrees almost word for word with the 

 view already advanced in this country (" The Tornado," pp. 57, 

 58, and others). Our author would account for the condensation 

 and precipitation at the centre from the partial vacuum produced 

 there by centrifugal action. 



The origin of the tornado funnel is sought in the upper air cur- 

 rent because there there is less friction, but no idea is given of even 

 the approximate height of this formation It the velocity of the 

 gyration becomes sufficiently great, and other conditions favor, 

 the funnel may reach the earth. This conclusion is also drawn: 

 "In wide extended cyclones is it somewhat different; here is it 

 very well thinkable, that, through the origin, or especially through 

 the stronger unfolding of the same, in the middle atmospheric 

 layers, which arise as well through the general circulation, as 

 also in consequence of local drawing-in of the air, even as well is 

 the air sucked into this whirl or eddy in the middle atmosphere, 

 from above as from below." This is a most extraordinary result 

 of this study. It is a little to be regretted that no idea whatever 



is given of the approximate height of this middle region, whether 

 5,000 or 10,000 feet. Our author finally concludes that there 

 may be a reconciliation between the anomalous results of tem- 

 perature conditions in storms and high areas, as found by Dr. 

 Hann, and his own studies here given, as well as between the 

 older convection theory and the eddy theory of M. Faye, more 

 recently adopted by Siemens and Hann. 



Professor Bezold's whole paper, of twenty-three royal-octavo 

 pages, is very interesting reading, and should be perused by every 

 one interested in the subject. It seems as though, in his attempts 

 to reconcile two theories which are diametrically opposed to each 

 other in almost every particular, he has indulged in some remark- 

 able flights of imagination, but that question I leave for discus- 

 sion to the advocates of each theory. Faye's view, that our 

 storms ai'e eddies in the upper atmosphere, seems to be gaining 

 gi-ound, and has already been accepted by Siemens and Hann. In 

 Science for March 13, p. 1?1, I have suggested that " these views 

 are entirely at variance with the facts observed in this country, 

 and cannot possibly be accepted as an explanation of the phe- 

 nomena in question." I desire to advance a tew facts which 

 show how untenable such an hypothesis as this eddy theory is. 



1. The direction of the upper current does not coincide with 

 that of the storm, but is very often at right angles to it. 



3. The velocity of each stratum increases as we rise in the at- 

 mosphere to about 15,000 feet or a little less, and then diminishes; 

 and in only a very limited stratum, perhaps at about 5,000 feet 

 or less, is it the same as that of the storm. It is easy to see that 

 no eddy could possibly he maintained more than a few minutes 

 under such conditions. 



3. The existence of the high area is practically ignored in this 

 theory, though it must be very evident to every student of mete- 

 orology in this country that the high area is almost as important 

 as the storm, and is built up under somewhat similar conditions, 

 though with an opposite sign. To be sure M. Faye regai'ds the 

 high area as a static phenomenon, being led thereto by the sta- 

 tionary character exhibited by it in Europe, but in this country it 

 is almost as much a dynamic phenomenon as the storm itself. 



4. There are no obstructions, or counter currents at the same 

 level, which can be invoked in calling such eddies into existence. 



5. Even if it be granted that such an eddy can originate in the 

 upper atmosphere, it is plain that its gyrations could not be 

 transmitted to the earth through a frictionless medium. It has 

 been computed that about twenty years would be needed for the 

 communication of such conditions, through friction, in an air 

 thickness of only three hundred feet. 



6. If such an eddy should begin in the upper atmosphere, it is 

 perfectly certain that absolutely no precipitation could result from 

 it, for its downward propulsion, if it could occur, would serve to 

 thoroughly dry the air. 



7. High-level observations in this country show that a good 

 share of the variation in pressure in our high areas and storms is 

 far above the highest mountains, and very far from where any 

 appreciable eddy could be formed. 



8. There is absolutely no whirl in the air above 4,000 feet or 

 less. This is fatal to this eddy hypothesis. 



In kcienee for June 5 is an abstract or short statement of a pa- 

 per, by Rev. W. H. Dines, read before the Royal Meteorological 

 Society, in which were discussed these theories of storms: (1) The 

 convection theory, or Espy's; (2) the eddy theory, or Faye's. To 

 these I wish to add two more: (3) the wave theory, first jiroposed 

 by Archibald, so far as I know, in tbese words: "Many facts, 

 such as the observed direction of the upper clouds over and sur- 

 rounding a cyclone, the velocities at the surface indifferent quad- 

 rants, the retardation of the barometric minima at mountain sta- 

 tions, and the frequently small elevation reached by the entire 

 disturbance (not more than 6,500 feet, according to Loomis), tally 

 more with a species of wave-motion by which the conditions are 

 continually reproduced in a certain direction, than with the drift 

 theory, and in any case require other and additional causes for 

 their complete elucidation" {Nature, June 14, 1888, p. 151). This 

 same theory has been independently advanced by Mr. John Eliot 

 of India (SciOice, May 29, 1891). This theory is undoubtedly a 

 great advance on the others, but is not entirely satisfactory. It 



