876 



SCIENCE. 



[N. S. Vol. XX. No. 521. 



decreases faster and faster as one rises in 

 the air and that not only is there a large 

 seasonal variation at the greatest heights 

 attained, but that non-periodic changes 

 occur from day to day, as they do at 

 the earth's surface. Still more remark- 

 able is the indication of a warm current 

 at a height of about seven miles, while 

 the stratification of the atmosphere as re- 

 gards temperature, moisture and wind has 

 been shown by the kite-flights at Blue Hill 

 to be a normal condition, and not merely 

 confined to the high atmosphere as was 

 formerly supposed. Daily soundings of 

 the atmosphere to the height of a mile or 

 two are now being made with kites and 

 captive balloons at the meteorological insti- 

 tutes of Berlin, Hamburg and St. Peters- 

 burg, and are furnishing valuable data 

 concerning the changes in the meteorolog- 

 ical elements which occur simultaneously 

 or successively in the overlying strata. 



Of the various unsolved questions relat- 

 ing to this subject perhaps the most impor- 

 tant is whether the core of the cyclone pos- 

 sesses the excess of temperature over the 

 surrounding body of air which the convec- 

 tional theory of its origin requires. We 

 need to know also the height to which the 

 cyclone extends, the circulation around it 

 at various levels, and fiirther to generalize 

 the theory of an accompanying cold-center 

 cyclone in the upper air, deduced by Mr. 

 Clayton from the Blue Hill observations. 

 Other vexed questions can be elucidated 

 by similar researches, such as the conditions 

 favorable for precipitation and the action 

 of dust-nuclei in producing it, the source 

 of our American cold-waves, the exact rela- 

 tions of thunderstorms and tornadoes to 

 centers of pressure and temperature and, 

 finally, the causes which, in the upper air, 

 influence the trajectories and velocities of 

 the cyclones and anti-cyclones that give us 

 our broader weather features. When these 

 correlations are determined from the in- 



vestigations of the free air now in prog- 

 ress, and we possess a sufficient number of 

 aerial stations to make it possible to chart 

 a daily map of the upper air, then we may 

 expect an improvement in the weather fore- 

 casts. The prediction of fog over the 

 ocean on, and adjacent to, our coasts is of 

 great practical importance to shipping, 

 especially off the banks of Newfoundland, 

 and the writer believes that meteorological 

 kites flown from a steamer in these regions 

 would reveal the unknown relations of 

 temperature, humidity and wind in and 

 above the fog-bank which might lead to 

 the prediction of the conditions favorable 

 to its formation. 



We now pass to another branch of 

 meteorological research, namely, the 

 cosmical relations. It is incontestable that 

 the sun, the source of all terrestrial energy, 

 has great influence upon the mag-netic con- 

 ditions of the earth, but a consideration 

 of the relation of terrestrial magnetism 

 and meteorology will be left to my col- 

 league, Dr. Baixer. The cause of atmos- 

 pheric electricity has always been an 

 enigma to meteorologists, but the discovery 

 of 'ions,' or 'electrons,' as carriers of 

 electricity, has thrown some light on this 

 question. It is of importance in geophysics 

 to know how the capacity of the air for 

 positive and negative electrons varies with 

 altitude, and also the periodic and non- 

 periodic variation of the potential at the 

 earth's surface. 



Attempts to regard all atmospheric phe- 

 nomena as periodic and due to the influence 

 of the sun or moon have long occupied the 

 attention of eminent investigators, but it 

 ]nust be admitted that the effects of neither 

 the periods of solar nor those of lunar rota- 

 tion upon the earth's meteorology can be 

 claimed to have been proved, although a 

 correspondence has been found by the dis- 

 tinguished speaker who preceded me in 

 regard to the frequencies of auroras and 



