8o 



SCIENCE. 



[Vol. XVI. No. 392 



these stations attendant upon and immediately following the pas- 

 sage of the crest of anti cyclones over New England is very strik- 

 ing. 



The results of these observations may perhaps be summarized 

 briefly in the statement that temperature changes indicate their 

 approach at the summit of Mount Washington sooner than at its 

 base. Thus, the departure of an anti-cyclone is signalized by a 

 rise of temperature amounting, in the cases above described, to an 

 actual inversion of temperature as compared with surrounding 

 stations. In like manner the departure of a low centre is marked 

 by decided decrease of temperature at the summit as compared 

 with lower levels. In the former case there is equalization and 

 in the latter case increased divergence of temperature at different 

 altitudes. Hence it follows that relatively warmer air overlaps an 

 anti cyclone at least as far east as its crest, and in like manner 

 relatively colder air tends to overlap the warm air at cyclonic 

 centres, but the extent to which it does so is not so clearly defined 

 as in the case of the anti-cyclone. M. A. Veeder. 



IjyoDs, N.Y., Aug. 1. 



Dr. Sprung: Remarks on the General Wind-Systems of the 

 Earth. 



In the American Journal of Science for April I have called 

 attention to the recent activity on the part of investigators in the 

 field of dynamical meteorology. In that paper no attempt was 

 made to give any opinion as to the relative merits of the different 

 theories advanced. There could be no doubt but that a critical 

 review of the subject was very much needed, but it must be at 

 the hands of some one who had mastered the different theories 

 with a thoroughness which would permit of his making a just 

 estimate of the value of the ideas advanced by the writers. There 

 was no doubt in my mind as to who was a (perhaps I should say 

 the) proper person to give us this estimate. I refer to Dr. Adolph 

 Sprung. It was with the greatest pleasure, then, that, on taking 

 up the May number of the Meteorologisehe Zeitschrift, I found 

 there a paper of sixteen pages by Sprung, in which he had given 

 his views as to the correctness of the methods and some of the 

 main results arrived at in these recent papers. 



But before giving a synopsis of this referat, it may not be out 

 of place to say a few words about Dr. Sprung's work, as he is 

 probably known to but few of the present readers in any other 

 capacity than the author of the "Lehrbuch of Meteorology," 

 which gives us such an excellent presentation of the modem 

 theories concerning statical and dynamical meteorology. Dr. 

 Sprung's contributions to meteorology extend over a period of 

 about fifteen years, and cover a wide range of topics. But there 

 are two distinct lines in which he has made his name especially 

 prominent as a specialist: viz., those which relate to self-register- 

 ing instruments, and the mechanics of the atmosphere. He has 

 devised a self-registering apparatus of great accuracy, which is 

 gradually receiving a wide adoption; and the fact that its con- 

 struction is in the hands of the leading German meteorological 

 instrument-maker is itself a guaranty of its excellence. The 

 names of " Wild " and " Sprung " will always be associated with 

 the development of this important branch of meteorology. 



It is, however, of Sprung's connection with the second topic, 

 that of dynamical meteorology, that I wish to make special men- 

 tion at the present time. From the commencement of his meteoro- 

 logical labors at the Deutsche Seewarte he has been a careful 

 student of this subject; and his acquaintance with its now exten- 

 sive literature is not of a cursory nature, but admits of his using 

 the methods and results of contributors in a manner which denotes 

 thorough comprehension. Judging from Sprung's writings, as 

 well as by a long personal intercourse with him, I feel justified in 

 saying that no one has a better knowledge than he, of the con- 

 tents of the hundred papers which cover the field of dynamical 

 meteorology. I do not know of a better example of the thorough- 

 ness of this study than his review of Part II. of Ferrel's " Meteoro- 

 logical Researches," which he published in the Osterreiche Zeit- 

 schrift fur Meieorologie nearly ten years ago. In this same con- 

 nection I may also say that no other person has done so much as 

 Dr. Sprung towards making generally known lo Europeans the 

 great service of Professor Ferrel to meteorology. 



In the comparative treatment given by Sprung in the paper 

 now under consideration, he prefaces it by some general remarks 

 which are of interest to us; and I will give an abstract of these, 

 as well as of portions of the main paper. 



The general circulation of the atmosphere has been lately the 

 subject of theoretical investigation, and principally by German 

 investigators, although earlier — through a number of years — the 

 workers in this field had been almost exclusively Americans, and 

 foremost of all was William Ferrel. But in 1886 Werner von 

 Siemens published an important paper, which was the first of the 

 series just referred to. In this investigation the results already 

 obtained by Ferrel in his earlier works were not made use of, and 

 the matter was treated from the first principles. But in all of the 

 investigations an ideal and homogeneously formed earth's surface 

 is presupposed; that is, it is assumed to consist everywhere of 

 water or land of like qualities. On this supposition there is 

 built up an ideal pressure distribution and system of winds. 

 Moreover, all of the systems agree with the view so long ago ad- 

 vanced by Hadley, as to the initial cause of the atmospheric cir- 

 culation. 



The theory of Werner von Siemens is first outlined, not because 

 it is the oldest of the modem views, but because it is the simplest. 

 It may be briefly stated as follows: We must conceive the air to 

 be everywhere at relative rest; the atmosphere will then possess, 

 by means of its absolute motion of rotation, a certain amount of 

 living force K. Now suppose the whole atmosphere to be sud- 

 denly thoroughly stirred up. Then, according to Siemens, there 

 will be produced an everywhere uniform velocity of rotation C, 

 and of such an amount that the total living force is just the same 

 as before. 



We will determine C. By definition 



(1) ^=^' 



where m denotes the mass of a quantity of air, and V its absolute 

 velocity of rotation (that towards east is positive) ; under which 

 supposition we have 



(2) V= u Reosij), 



where R is the radius of the earth (considered as a sphere), a is 

 its constant angular velocity, and ip the geographical latitude. In 

 order to represent the mass m, covering a small ring at the lati- 

 tude R-d <p and radius R cos ^, we will designate by p the mass 

 (assumed to be uniform) over the unit of surface : we have, then, 



(3) m = 2 /i jff TT cos (p d (j) {= d M, where M signifies the mass of 

 the whole atmosphere): consequently 



In general, 



(4) 



K 



f^ 



,m.^.f_ 



h^ , 



. JTT 



(3 -1- cos^ ( 



which for the limits ^ and — Jtt reduces to 4; therefore we 



have finally 



(5) K = ^ iiR* li' n. 



If, now, the computation of the living force for a uniformly 

 equal velocity C furnishes the same amount, then 



, TO C' 



K=J,- 



(6) 



C x: 



-13 



2 m. 



From (3) we have, then, • 



(7) M='I,m = 2/iR'' nf^ ^^ cos (p d = (p = i fi R' it. 



By consideration of (5) we have, then, 



(8) C = Ra Vi (= 379 metres per second). 

 Subtracting from this R a cos ip, the motion of the earth at the 



latitude (p, and we get the relative easterly motion v ; then from 



(8) and (2) we have 



(9) « == iJ u ( fl — cos 0). 



It is of special interest to find the latitude ip^ in which v = 0. 

 Tills gives 



For the belt between the two parallels of 35", there must be, ac- 

 cording to (9), a westerly air-current (east wind) which is greatest 



