100 JOURNAL OF THE [April, 



the Hay-Fever guests is severe and general. Happily it does 

 not continue, but passes off with the change of wind. On 

 the theory of a neurosis, the cause seems plain to me. 

 With the sudden humidity of the atmosphere, and low ba- 

 rometer, the tonic of the mountain air is dissipated, and 

 nervous depression results. Then, since the air in this condition 

 is surcharged with pollen, and other impurities, the nerve end- 

 ings of the respiratory passages are irritated unto acute 

 inflammation. 



At the closing session of the United States Hay-Fever Asso- 

 ciation, last September, at Bethlehem, N. H., a long-cherished 

 desire was revived to learn the relative hygienic quality of the 

 favored sanitaria, and that of places where the malady prevails. 

 Owing to my official relation, it fell to me to state the factors in 

 such a determination. 



The problem to be solved might be called the Hygiene of the 

 Atmosphere. It would involve, all through, consideration based 

 upon instrumental work. This would need such records of the 

 winds, humidity, range of the barometer and thermometer, as 

 fall to the meteorologist. The impurities, organic and inorganic, 

 of the atmosphere must also be considered, which side of the 

 work would fall to the microscopist. If density were added, 

 this would cover all. 



A word as to the conveyability of material particles by the 

 atmosphere. There is something ad capiandum in the splurge 

 of the lugubrious poet : — 



" The dust we tread upon was once alive." 



But, in the present tense, how true is this of the dust we 

 breathe ! Can we not recall the painful interest excited by 

 Tyndall's experiments on the impurities of the atmosphere ? 

 And, for our purpose, how easy to repeat some of them. Let a 

 beam of sunlight through a hole in the shutter enter a dark 

 room. It appears as a slanting, living column. I say living, for 

 every particle seems in motion, due to the incessant dancing 

 movements of millions of motes. 



If now a small spirit-flame, yielding no smoke, be held under 

 this beam, there will soon be seen a dark hole right through the 

 column. Withdraw the flame, and soon the contiguous motes 

 dance into it ; it is again illumined, and the dark hole disap- 



