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Vol. XV. NEW YORK, Mat 23, 1890. No. 331. 



CONTENTS: 



.... 309 , Book-Reviews. 



The Stanley Medal 309 



Tuberculous Milk 309 



The Tornado : Appearances ; 

 Lieut. Finley's Views. 



H. A. Hazen 310 



Notes and Kews 314 



Letters to the Editor. 

 To Discuss Meteorological Top- 

 ics. James P. Hull 318 i Among the Publishers 



Midnight Talks at the Club. ... 

 Epitomes of Three Sciences . . . 

 Pure Logic and Other Minor 



Works 



How to Remember History 



THE TORNADO: APPEARANCES; LIEUT. FINLEV'S 

 VIEWS. 



[Continued from p. 314. J 



Lieut. Finley's Views. 

 For the past ten years Lieut. Finley has devoted a great 

 deal of attention to this subject, and has received reports of 

 tornadoes from thousands of observers. His views, then, 

 should have much weight as being a resume of all the facts 

 reported. Quotations will be made from his book entitled 

 " Tornadoes," published in 1887 by the Insurance Monitor. 

 No attempt has been made to classify these, but I have 

 given them in the order in which they occur in the book. 

 Speaking of the flow of air on either side of a la'rge storm, 

 we find, " As these conditions continue to prevail, there is a 

 growing contrast of temperature to the north and south of 

 the major axis (of the depression), owing to the long-con- 

 tinued movementof the atmosphere from opposite directions; 

 such movement eventually affecting the disposition of air in 

 the warmer regions of the extreme south, and likewise the 

 colder regions of the extreme north. The contrast of tem- 

 perature now natvitally increases witli marked rapidity, and 

 the formation of clouds commences in earnest, iluge 



masses of dark and portentous appearance bank up in the 

 north west and so;ith-west with amazing rapidity, and soon 

 the scene becomes one of awful grandeur. The strugsrle for 

 mastery in the opposing currents is thus indicated by the 

 gathering cloud-formations. The condensation of vapor 

 from the extremely humid southerly currents by contact 

 with the augmenting cold of their struggling opponents con- 

 tinues. It increases rapidly. Finally, when resistance to 

 the unstable equilibrium can no longer be maintained (con- 

 trolled by the rate of temperature change and rapidity of 

 condensation), the opposing forces are, as it were, broken 

 asunder, followed by the upward rush of huge volumes of 

 air. The outward indication of this event is first shown in 

 the whirling, dashing clouds over the broken surface of the 

 heavy bank of condensed vapor, forming the background, — 

 a scene not easily depicted or realized by one who has not 

 witnessed it, but never to be effaced from the memory of the 

 actual observer. There is an awful terror in the majesty of 

 tiie power here represented, and in the unnatural movemi-nt 

 of the clouds, which affects animals as well as human 

 beings. The next stage in the further development of this 

 atmospheric disturbance is the gradual descent of the funnel- 

 shappd cloud from a point apparently just beneath the posi- 

 tion of the enactment of the first scene. The tornado is now 

 before us, not fully developed, but soon to acquire that con- 

 dition when the terrible violence of its power will make the 

 eartli tremble, animals terror-stricken, and men's hearts 

 quake with fear." 



" There seems to be some strange connection between the 

 almost simultaneous appearance of clouds in the south-west 

 and north-west, possessing as they do such unusually threat- 

 ening forms. As they approach from opposite directions, 

 they are suddenly thrown into the greatest confusion, break- 

 ing up, as it were, into small portions, which dash pell-mell 

 over each other and in every direction ; now darting toward 

 the earth; new rushing upward to considerable heights like 

 sky-rockets, c at moderate elevations rolling over each 

 other in a well-developsd whirl. An observer, in describing 

 the approach of the clouds from the south-west and north- 

 west, stated that they came together with a terrific crash, 

 as if thrown from the mouths of cannons. Generally, fol- 

 lowing closely upon the existence of this condition, the 

 funnel-shaped tornado-cloud appears against the western 

 sky, moving boldly to the front from without this confused 

 mass of flying clouds." Lieut. Finley describes four motions 

 of the tornado: '" No. L is called the whirling or gyratory 

 motion, which is invariably from right to left. Above all 

 other motions, this is attended with the greatest violence. 

 This gyratory motion forms what is termed the ' vortex' of 

 the tornado-cloud, within which the velocity of the centrip- 

 etal currents of air is almost beyond conception. No. II. 

 is called the progressive motion of the tornado, — the motion 

 which determines the cloud's track from one point to 

 another. No. III. is termed the rising and falling motion 

 of the tornado. No. IV. is called the zigzag motion, or 

 swaying from side to side of the central line of cloud-move- 

 ment. This movement is sometimes quite suddenly per- 

 formed, but generally it is a moderately slow movement, and 

 one that can be watched and easily identified. In complet- 

 ing the extent of a single act of ■this motion, the tornado- 

 cloud will diverge about an equal distance on either side of 



