462 



NATURE 



[March 17, 1892 



this late date. I can itill only repeat here what I said before, 

 as follows : — 



" My idea is, briefly, that the first depression occurred as the 

 storm passed on its westward track, followed by the usual shift 

 of wind to the northward. Along this branch of its trajectory 

 its severity was probably not quite so great as it was later, and the 

 force of its southerly winds was masked by the mountains on the 

 island of Upolu ; possibly careful observations of the rapidity of 

 motion and the character of the clouds, or of the state of the 

 sea off" the harbour, might have indicated a severe storm, but 

 this does not appear from the evidence at hand, though well 

 worth considering. During its recurve the hurricane probably 

 increased in intensity, the barometric depression at the centre 

 deepening, and thus causing the second depression observed at 

 Apia, which was slightly deeper than the first, although the 

 centre itself was really at a greater distance than on the previous 

 day. " 



Unfortunately, as stated above, we have no very definite data 

 regarding the severity of the storm before it reached Apia, 

 although I must say that a barometric depression of 076 inch 

 below the normal in the tropics is very suggestive of the 

 presence of a fully developed vortex, and it seems more than 

 likely that if the harbour had not been well sheltered to the 

 southward the southerly gales would have been quite as severe 

 as those from the north. The only early data that we have, 

 other than the reports from Apia, are contained in the following 

 very brief report from the American schooner Equator, Captain 

 Reid: — 



"March 14 (Samoan date), lat. 12° 00' S., long. 170° 50' W., 



wind S., S.W., W., N.W. ; thick, squally; hove to. 

 "March 15 (Samoan date), lat. 13° 00' S., long. 170^ 40' W., 

 wind N.W. ; fierce gale ; squalls ; heavy sea." 



This, although brief, seems to indicate that it was a fully 

 developed hurricane that was approaching Apia, and I am 

 inclined to the opinion that such was actually the case. 



Mr. Blanford will surely admit that it is one recognized 

 peculiarity of tropical hurricanes to reduce their speed of trans- 

 lation whilst they are recurving, and he will thus admit also 

 that such recurvature accounts, in the present case, for the 

 duration of the northerly gale at Apia. So far as the sharpness 

 of recurvature is considered, I would say that the report of the 

 Equator is sufficiently vague to allow us to draw a curve with a 

 somewhat less sharp recurvature, and I should myself have done so 

 but for the single fact that a hurricane approaching from a more 

 northerly direction must have sent a northerly or north-easterly 

 swell into the harbour that would have been felt to at least such 

 an extent as to be noted in the log of one or more of the vessels 

 there, but I have looked in vain for any such remark, until after 

 the shift of wind on the afternoon of the 15th. 



In conclusion, I take pleasure in expressing my obligation to 

 Mr. Blanford for his interesting and able discussion of the 

 subject, which, even with all the data at hand, has still many 

 perplexing features. The principal object of this preliminary 

 publication was to elicit comment and discussion, and it will be 

 very gratifying if other authorities will give us the benefit of 

 their experience and suggestions. 



Everett Hayden. 



Hydrographic Office, Washington, D.C., 

 January 4. 



The distinction to which allusion was made in the passage 

 quoted by Mr. Hayden is not, as he seems to have understood, 

 that between tropical and extra-tropical storms when fully formed, 

 but between the circumstances of their respective formation. 

 These are that, in the former, the cyclonic circulation of the 

 winds is preceded by much irregular action, which sometimes 

 extends over a considerable area. Within this area there are 

 local squalls and shifts of wind, with heavy rainfall, but the 

 action is not for some time definitely conpentrated and cyclonic. 

 This preliminary stage does not appear to obtain in the storms 

 of the temperate zone, where the deviating effect of the 

 earth's rotation is so much greater than in low latitudes, and 

 indeed, if we accept the views of Werner Siemens and Prof. 

 Hann, the cyclonic circulation is the cause and forerunner of 

 the storm. I cannot think it probable that a vortex, once fully 

 formed, and travelling towards higher latitudes, should recurve 

 so sharply as to produce a fall of the barometer on iwo 

 successive days (with a rise in the interval) at the same place, 

 simply by twice passing in its vicinity. To effect this, the 



NO. I 168, VOL. 45] 



recurvature must, as I apprehend, describe an angle consider- 

 ably less than a right angle, and of such I know of no example 

 among tropical cyclones. At the same time, my own view was 

 put forward merely as a suggestion, and in no dogmatic spirit. 

 H. F. B. 



Phoronomy, 



About thirty-five years ago, I had a conversation with the late 

 Dr. Donaldson, a well-known Greek scholar of the time, in 

 which we discussed the appropriateness of, the use of the word 

 kinematics, in the sense in which it was then, and is now, 

 employed by writers on mathematical science. Dr. Donaldson's 

 opinion was that it is not the best word which can be employed 

 to represent the science of pure motion, without regard to causa- 

 tion. He said that the word Kiveoi involved the idea of the cause 

 of motion, and therefore that it ought not to be used when the 

 idea of causation is to be completely set aside. He further gave 

 it as his opinion that the word ipopew is more nearly expressive of 

 the idea of mere going, without any reference to the cause of 

 motion, and therefore that the proper word would be phoronomy, 

 or phoretics. 



1 was so much impressed by this conversation that, for many 

 year?, I headed with the word phoronomy the papers of questions 

 on the subject of pure motion which I was in the habit of pre- 

 paring for College lectures and private pupils. 



I have recently consulted a very eminent Greek scholar, 

 and his opinion is that, on the whole, the word phoronomy 

 is more distinctly expressive of the science of pure motion 

 than the word kinematics. He agreed with Dr. Donaldson 

 that the word kinematics suggests some idea of causation, 

 whereas no such idea is suggested by the word phoronomy. 



As a matter of history, the word cinemaiique was introduced 

 by Ampere to represent the purely geometrical science of motion 

 in the abstract, and was anglicized into kinematics by, I 

 think, the late Dr. Whewell. 



Sir W. Thomson and Prof. Tait, in the preface to their 

 " Natural Philosophy," adopt the suggestion of Ampere, and 

 employ the word in the same sense. They also employ the word 

 dy7taviics in its true sense as the science which treats of the 

 action of yj7;r^, whether it maintains relative rest, or produces 

 acceleration of relative motion. They further state that these 

 two corresponding divisions of dynamics are conveniently en- 

 titled statics and kinetics. 



Here, then, we have two words, kinematics and kinetics, both 

 derived from the same root-word, employed to represent two 

 entirely different sets of ideas ; and there is not;the same broad 

 line of demarcation between the words themselves as there is 

 between the sets of ideas which they are intended to connote. 



Hence it appears to me that the word phoronomy, the law of 

 going, is the most suitable, as it is the most expressive word, 

 to represent the science of pure motion in the abstract. 



At the time of my conversation with Dr. Donaldson, we were 

 neither of us aware that the word had been already invented 

 and employed. Some years after, I found that a treatise was 

 published at Amsterdam in 1716, entitled " Phoronomia, sive 

 de viribiis et m.otibus corporum. Autore Jacobo Hermanno, 

 Basil." Hermann, however, uses the word in much the same 

 sense as we now use the word dynamics. 



The point has been recalled to my mind by the discovery 

 that the word has been employed in Germany in the sense in 

 which Dr. Donaldson advocated that it should be used. 



In the treatise entitled " AUgemeine Mechanik der Punkte 

 und Starren Systeme," by E. Budde, published in 1890 at 

 Berlin, the word phoronomy is adopted, and the author gives 

 his reasons in the following words : — 



"Man kann eine Ortsveranderung zunachst rein geometrisch, 

 ohne alle Riicksicht auf ihre Ursachen, betrachten, und das 

 soil in den nachsten Capiteln geschehen. Die Disciplin, 

 welche sich mit dieser Betrachtung befasst, heisst Phoronomie 

 Oder Kinetnatik. Der Name Kinematic ist seit Resal der 

 gebrauchlichere gewesen ; neuerdings aber wird von Reulaux 

 und seinen Schiilern die Morphologic der Verkniipfung von 

 Maschinentheilen als ' Kinematik ' bezeichnet. Wir wiihlen 

 deshalb hier den Namen Phoronomie." 



With reference to this statement of Budde's, I observe that 

 Ampere, in the " Essaie sur la Philosophic des Sciences," 

 particularly mentions trains of machinery, such, for instance 

 as the works of a watch, as coming under the heading 

 kinematics. 



I also find that Grassmann, in the " Ausdehnungslehre von 



