496 



SCIENCE. 



[N. S. VoL.XVIII. No. 459. 



to guide us. So far as meteorology is con- 

 cerned, Willard Gibbs unfortunately left 

 his worJi unfinished. 



When the cyclonic depression was re- 

 luctantly recognized as too unstable a crea- 

 ture to carry the structure of a general 

 theory, Mr. Galton's anticyclones, the areas 

 of high pressure and descending currents, 

 claimed consideration as being more per- 

 manent. Professor Koppen and Dr. van 

 Bebber have watched their behavior with 

 the utmost assiduity and sought to find 

 therein a unit by which the atmospheric 

 changes can be classified ; but I am afraid 

 that even Dr. van Bebber must allow that 

 his success is statistical and not dynamical. 

 'High pressures' follow laws on the aver- 

 age, and the quantity we seek is not an 

 average, but an individual. 



The question arises, whether the knowl- 

 edge of the sequence of weather changes 

 must elude us altogether, or will yield to 

 further search. Is the man in the street 

 right, after all? But consider how limited 

 our real knowledge of the facts of atmos- 

 pheric phenomena really is. It may very 

 well be that observations on the surface 

 will never tell us enough to establish a 

 meteorological entity that will be subject to 

 mathematical treatment; it may be that 

 we can only acquire a knowledge of the 

 general circulation of the atmosphere by 

 the study of the upper air, and must wait 

 until Professor Hergesell has carried his 

 international organization so far that we 

 can form some working idea therefrom 

 of general meteorological processes. But 

 let us consider whether^ we have even at- 

 tempted for surface meteorology what the 

 patience of astronomers from Copernicus 

 to Kepler did for astronomy. 



Do we yet fully comprehend the kine- 

 matics of the traveling depression; and if 

 not, are we in a '=:atisfactory position for 

 dealing with its dynamics? I liave lately 



examined minutely the kinematics of a 

 traveling storm, and the results have cer- 

 tainly surprised me and have made it clear 

 that the traveling depressions are not all 

 of. one kinematical type. We are at present 

 hampered by the want of really satisfac- 

 tory self-recording instruments. I have 

 sometimes thought of appealing to my 

 friends the professors of physics who have 

 laboratories where the reading of the ba- 

 rometer to the thousandth of an inch be- 

 longs to the work of the ' elementary class, ' 

 and of asking them to arrange for an oc- 

 casional orgy of simultaneous readings of 

 the barometer aU over the country, with 

 corresponding weather observations for 

 twenty-four consecutive hours, so that we 

 might really know the relation between 

 pressure, rainfall and temperature of the 

 traveling depressions; but I fear the area 

 covered would even then hardly be large 

 enough, and we must improve our self- 

 recording instruments. 



Then, again, have we arrived at the ex- 

 tremity of our knowledge of the surface 

 circulation of the atmosphere? We know, 

 a great deal about the average monthly 

 distribution, but" we know little about the 

 instantaneous distribution. It may be that 

 by taking averages we are hiding the very 

 points which we want to disclose. 



Let me remind you again that the thick- 

 ness of the atmosphere in proportion to the 

 earth's surface is not unsatisfactorily rep- 

 resented by a sheet of paper. Now it is 

 obvious that currents of air in such a thin 

 layer must react upon each other horizon- 

 tally, and, therefore, we can not a priori 

 regard one part of the area of the earth's 

 surface as meteorologically independent of 

 any other part. We have daily synoptic 

 charts for various small parts of the globe, 

 and the Weather Bureau extended these 

 over the northern hemisphere for the years 

 1875 to 1879 ; but who can say that the 



