458 



NATURE 



[Sept. 23, 1875 



the theory of attraction. Why ellipses ? said theorists at 

 the beginning of the seventeenth century. And why put 

 the sun in the common focus of all these ellipses ? Are 

 there not also other curves followed by these planets in 

 their course around the sun ? But once connected with 

 the principle of universal gravitation, these laws, so 

 neglected by contemporaries, became "the immortal laws 

 of Kepler." 



Such at present is the position of the Laws of Storms. 

 Despite the adhesion of practical men, meteorologists do 

 not recognise the essential features which ought, according 

 to them, to characterise storms. On this account, the 

 practical rules themselves which sailors have followed for 

 thirty years must be rejected ; for they are entirely 

 founded, as we have seen/on the circular movement of 

 the air in storms. 



These criticisms,' more or] less direct, based on the 

 theory of centripetal hurricanes or of aspiration, have 

 at the present time all the greater force that mariners 

 themselves have an innate belief in the mere idea of this 

 theory. We even find this belief in the writings of 

 authors who have shown themselves best acquainted 

 with the laws of storms and with the corresponding 

 practical rules. Two examples may be referred to. 



The well-known hydrographic engineer, Keller, in his 

 "Treatise on Hurricanes," says that in intertropical 

 regions where cyclones originate, the atmospheric strata 

 underneath the sun dilate and draw up the inferior air of 

 the dilated zone ; that if ordinary aspiration, due to the 

 calorific action of the sun, is further promoted by an 

 electric attraction, the affluent air will rush with more 

 force into the interior vacuum, &c. Within this space or 

 vacuum he conceives that the water of the sea raised by 

 the central aspiration of a typhoon or a waterspout 

 ascends. When the gyratory column passes from the sea 

 on to the land, it hurls against the shore the water raised 

 by aspiration, and the sea suddenly inundates the low 

 coast to a considerable distance inland. Finally, on land, 

 the force of aspiration of these phenomena exercises its 

 ravages not only by throwing down, but by tearing up 

 trees, and overturning even solid buildings. 



M. Bridet, again, asserts that there is formed under the 

 action of the sun, a sort of vacuum resulting from the 

 rapid ascension of masses of heated air. This vacuum is 

 rapidly filled up by the lower currents of air which flow 

 towards it from all directions. These currents, flowing 

 along the surface of the earth, acquire a gyratory motion 

 from the daily rotation. On reaching the base of the 

 ascending column, near the centre of rarefaction, the air 

 carried by these currents gets heated, and expands in its 

 turn ; it follows the ascensional movement of the mole- 

 cules that it replaces, and rises, preserving its rotatory 

 motion. 



Persuaded of the reality of this immense draught which 

 the aspiration of ascending columns of heated air must 

 exercise on the lower stratum, in the manner of a 

 chimney, sailors themselves must say that the circular 

 diagram which Reid and Piddington have used for cy- 

 clones is scarcely admissible from the theoretic point of 

 view ; that already the centripetal movement has been 

 recognised in waterspouts and tornadoes, which, after all, 

 are only cyclones in miniature ; that the convergent dia- 

 grams proposed recently by Mr. Meldrum, of Mauritius, 

 have perhaps a better foundation, more especially if, 

 as Mr. Meldrum affirms in the cases of two storms which 

 he has recently discussed, these convergent diagrams better 

 represent the true features of the hurricane than concentric 

 circles. Mr. Meldrum's " Note on the form of Cyclones 

 in the Indian Ocean " has been published by the Meteoro- 

 logical Committee of the Royal Society, and is thus well 

 known. We reproduce one of the figures (Fig. 4), and 

 ask the reader to compare it with the circular diagrams 

 of the hurricane in Cuba (Fig. i) ; the difference of the 

 two systems will be seen at once. 



According to the first the centre is situated perpendi- 

 cularly to the direction of the wind ; according to the 

 second, it will be situated (neglecting for the moment the 

 curvature of the spirals) in that very direction. There is 

 here a difference of nearly 90°. 



What will hereafter be the position of sailors in the face 

 of an imminent danger ? This is in substance what they 

 are told : — You feel, you see, that a danger menaces you ; 

 the aspect of the sky, the state of the sea and of the winds, 

 the steady fall of the barometer, already tell you that 

 there is not a moment to lose if you wish to take the step 

 which may save all. Hitherto you have believed, in the 

 faith of certain empirical rules, that the danger is on your 

 left ; not at all— by my theory it is before you. 



The captain has no time to search /the works of Reid, 

 of Redfield, of Piddington, or to examine the theory of 

 centripetal hurricanes. This is a question which must be 

 quickly answered. Is it necessary, in order to this, to 

 make one's self familiar with all that has been done during 

 the last thirty years in order to try, in this repetition of 

 the first investigation, if the centripetal diagrams repre- 

 sent the direction of the wind better than the circular 

 diagrams t This is a labour which would require at least 

 many years. 



Happily there is another method of solving the question, 

 which is to examine that theory of hurricanes of centri- 



petal aspiration which has given rise to all these doubts 

 with regard to the laws of storms. If this theory is found 

 to be true, the authors of the " Laws of Storms " will cer- 

 tainly have been wrong in neglecting its indications. Let 

 us therefore put aside their pretended circulatory move- 

 ments. The air moves towards^ a centre of aspiration 

 instead of turning round a point ; all will thus be changed, 

 and especially will it be necessary to promulgate practi- 

 cal rules altogether different. But if the' theory of aspi- 

 ration is proved to be false — and, to know what to believe 

 on the subject, long years are not necessary — a rapid 

 examination will be sufficient ; if it is false, we say, sailors 

 may continue to place confidence in the rules which have 

 been so serviceable to them for thirty years. 



By investigating the whirling movements of which the 

 sun is the theatre, M. Faye was led some time ago to 

 examine this theory without any reference to nautical 

 matters. He has found it completely illusory. On the 

 contrary, that theory which fits into the solar phenomena 

 is found to agree thoroughly with the Laws of Storms ; 

 and we need not be astonished at this agreement, for the 

 laws of mechanics are the same everywhere, and the 

 gyratory movements of fluid masses will not vary more 

 in the case of one heavenly body as compared with 

 another than the laws ot gravitation. Putting aside solar 

 questions, which interest only astronomers, we shall treat 



