332 



SCIENCE. 



[Vol. XV. No. 382 



damaging reports as to bis honesty ; but in every instance I 

 found bis statements borne out by other testimony or by 

 general analogy. Making due allowance for the mytbologic 

 features, which rather serve to establish its traditional char- 

 acter, his account is probably as full and accurate as could 

 be expected at this late day, and briefly is as follows:— 



" ' The practice of building mounds originated with the 

 Anintsi, and was kept up by the Ani-Kituhwagi. Tliey 

 were built as sites for town-houses (see Bartram's account 

 of Cowe mound and town-house) ; and some were low, while 

 others were as high as small trees. In building the mound, 

 a fire was first kindled on the level surface. Around the fire 

 was placed a circle of stones, outside of which were depos- 

 ited the bodies of seven prominent men, one from each gens, 

 these bodies being exhumed for the purpose from previous 

 interments.' 



"Swimmer said that his statement was obtained from a 

 man who died in 1865, aged about seventy. Some time 

 later, while talking with an intelligent woman in regard to 

 local points of interest, she menlioued the large mound near 

 Franklin, in Macon County, and remarked, 'There's fire at 

 the bottom of that mound.' Without giving her any idea 

 of what Swimmer had said, I inquired of her how the fire 

 got there, when she told substantially the same story as she 

 had obtained it from an old woman now dead. She was of the 

 opinion that this fire existed only in the larger mounds; but 

 I found oa investigatiou that the belief was general that the 

 fires still existed, and occasionally sent up columns of smoke 

 above the tops of the mounds." Cyeus Thomas. 



[To be continued.] 



LETTERS TO THE EDITOR. 



*** Correspondents are requested to he as brief as possible. Tlie loriter^s name 

 is in all cases required as proof of good faith. 



The editor will be glad to publisk any queries consonant with the character 

 of the journal. 



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

 be furnished free to any correspondent. 



Dr. Hann's Studies on Cyclones and Anticyclones. 



On April 17, Dr. Julius Hann, director of the meteorological 

 observatory at Vienna, presented to the Vienna Academy an es- 

 say on "The High Pressure Area of November, 1889, in Central 

 Europe, with Notes on High-Pressure Areas in General." The 

 particular value of the essay lies in the comparison of records 

 from lofty Alpine stations with those from the surrounding low 

 country; the highest station being on the Sonnhlick, over 3,100 

 metres above sea-level. The anticyclone of November, 1889, was 

 chosen because it lay over the Alpine region fiom the 12th to the 

 24th of the month, giving ample time for the full determination of 

 its persistent features. The results of the study ai'e thus summa- 

 rized: — 



1. The barometer maximum of November, 1889, extended to a 

 great height in the atmosphere, and was as pronounced at a height 

 of 3,000 metres as at sea-level. At a height of 2,500 metres, the 

 centre of high pressure lay over that at the earth's surface. 



2. The body of air in the anticyclone had a high temperature. 

 At 3,000 as well as at 1,000 metres, the temperature stood 8° C. 

 above the mean. The usual depression of temperature, charac- 

 teristic of winter anticyclones, was limited to the lower lay- 

 ers of air, next to the earth's surface, and was only a few hun- 

 dred metres thick. The mean excess of temperature over the 

 normal at successive heights up to 3,100 metres, for the pe- 

 riod from the I9th to the 23d of November, can be estimated as 

 at least 6° 0. An excess of temperature must, at the most mod- 



erate determination, have extended up to a height of 5,000 me- 

 tres. 



3. In the upper air, above 1.000 metres altitude, a great dry- 

 ness prevailed. The mean relative humidity from the 19th to the 

 23d of November on the Sonnblick (3.100 metres) was only 43 per 

 cent, and on the Santis (2,500 metres) 34 per cent, according to 

 carefully reduced psychrometer records. Hair hygrometers gave 

 a still lower percentage. 



Dr. Hann sees in these facts a strong proof of the descending 

 aiovement of the air in anticyclones, such as is generally accepted. 

 He then goes further in saying that the motion of the air is not a 

 product of the temperature, but is in spite of it: the temperature 

 is a product of the motion. 



A study is then made, for purposes of comparison, of an area 

 of low pressure that passed nearly centrally over the eastern Alps 

 on Oct. 1, 1889. Here the temperature of the air-column aver- 

 aged 4.3° C. below the thirty-year normal for the time and place. 

 Although earlier in the season, the air in this cyclone was abso- 

 lutely colder than that in the later anticyclone. Even while a 

 warm foehn was blowing down the northern valleys of the east- 

 ern Alps, the temperature on the Sonnblick was distinctly below 

 the normal. In reviewing this, Dr. Hann says that it is the high 

 mountain stations, recently founded, that have freed us from the 

 prejudices into vvhicb we have been led by observations at low 

 levels. It has been thought that the temperature of cyclones and 

 anticyclones was the chief condition of their motion; but it ap- 

 pears certain fiom the foregoing, that the theory of cyclones must 

 take account of the fact, that, up to the height of at least four or 

 five kilometres, the central air-column of an anticyclone may be, 

 and probably always is, warmer than that of a cyclone. 



It is manifest that this contradicts the prevailing theory of the 

 convectional origin of cyclones and anticyclones, while it conflrms 

 the views of those who, like Dr. Hann, regard cyclones and anti- 

 cyclones as merely subordinate members of the general circula- 

 tion of the atmosphere, their energy coming from the fundamen- 

 tal and persistent difference of temperature between the equator 

 and the poles. According to this view, as Dr. Hann says, the 

 temperature of the air-masses in cyclones and anticyclones is the 

 product of their motions, and not vice versa. In the stationary 

 cyclonic circulation of the far northern Atlantic, and in the win- 

 ter anticyclones of the continents, differences of temperature are 

 probably operative. Hence the author agrees with Teisserenc de 

 Bort in distinguishing between thermic and dynamic cyclones and 

 anticyclones. Moreover, in dynamic cyclones, the evolution of 

 latent heat will maintain the air-mass at a higher temperature 

 than that to which it would otherwise be reduced; buteventhen, 

 the descending air in the adjacent anticyclone will be warmer 

 as a whole than that which ascends in the cyclone. 



This most interesting conclusion as to the origin of cyclones is a 

 surprise to me; and therefore, having frequently advocated the 

 sufficiency of the convectional theory of cyclones, I now make 

 haste to place Dr. Hann's observations before the readers of Sci- 

 ence, that they may see how clearly a revision of opinion is called 

 for. The apparently convectional circulation in cyclonic storms 

 is not doubted. There is unquestionably an ascending component 

 of motion in cyclonic areas, and a descending component in anti- 

 cyclones. It also appears to be generally true that at the earth's 

 surface, temperatures above the normal are noted in cyclones, 

 and below the normal in anticyclones. It cannot be doubted that 

 the evolution of latent heat from condensing vapor in the rainy 

 cyclonic area would favor any convectional movement that had 

 originated from other causes. For all these reasons, the convec- 

 tional theory came into favor, and other possible explanations 

 were little considered. The convectional theory is merely a local 

 application of a theory that is universally accepted to account for 

 the general circulation of the atmosphere between equator and 

 poles; but the tests now furnished l)y high-level observations 

 seem to show that the local application of the theory is incorrect. 



This is as if an observer who was familiar with stationary 

 steam-engines should see a train of cars for the first time : he 

 would rather naturally say that the locomotive was the motor of 

 the train ; he would hardly suggest the possibility that the motor 

 was concealed in the rear car, and that the driving-wheels of the 



