THE CLIMATOLOGY OF THE UNITED STATES. 41 



solar system and that oftentimes unexplained phenomena 

 are but the manifestations of reactions between the mem- 

 bers of that system. Now to revert to the subject under 

 discussion ; it appears to me quite necessary to attribute 

 the cause of the "Yellow Day" to something higher than 

 smoke in the air, and I will mention a tew facts which 

 seem to make the smoke theory untenable. 



In the first place, it is granted that in the neighborhood 

 of an extensive fire the sky assumes a murky hue from 

 the smoke ; but there have been many forest fires of great 

 magnitude in the regions to the northeast, north, north- 

 west and west of New England without being followed by 

 any such conditions as were present on the "Yellow Day." 

 It is claimed that the wind was not in the proper direc- 

 tion on these occasions, but that on the "Yellow Day" it 

 was. 



Now let me say that though there may possibly have 

 been a little smoke in the air in northern New Hamp- 

 shire and Vermont, yet the yellow light of that day 

 appeared over other parts of New England nearly simul- 

 taneously. If smoke had been the cause, we should have 

 had a gradual thickening of the sky, as the smoke ad- 

 vanced from one district to another southward and it 

 would have passed away in the same gradual way. Such 

 was not the case ; it appeared in a short space of time 

 and disappeared with the sun. Furthermore, if the wind 

 had been violent enough to have brought such an im- 

 mense volume of smoke down over New England and 

 carried it away so suddenly, then that wind, even if at a 

 high altitude, must have caused some motion in the air 

 next to the earth. But the air was calm on that day, and, 

 again, if such an amount of smoke had been carried 

 along over so large a territory in so short a time, it would 

 have presented more the appearance of masses of clouds 



KSSKX INST. BULLETIN, VOL. XVIII. 5 



