380 BOTANICAL INFORMATION. 
by the same accurate maker for comparison on my return home. 
But this soon shared the fate that usually befalls these fragile aids 
to science, when on foreign service, nor could I replace its loss 
by an instrument of equal susceptibility, or on whose scale I 
could as perfectly rely. I found, too, that even when stationary, 
it was seldom possible for me to make choice of a situation in 
which a thermometer. could give results worth recording from the 
effect of radiation or of improper aspect; besides, that the publi- 
city of a traveller's ordinary places of sojourn in America puts his 
apparatus in perpetual danger of breakage, and it may be even of 
abstraction.* Add to these difficulties the impossibility of making 
a continuous or regular series of observations, and the propriety 
of omitting such notices of temperature, except in an occasional 
way, will, I think, be obvious to most persons. 
With regard to the greater clearness, or (to speak more cor- 
rectly) increased transparency, which so many travellers pretend 
to discover in the transatlantic atmosphere, over that of Europe, 
or, at least, of our own, I apprehend that there, as in England, 
and most other parts of the temperate zone, this attribute be- 
longs rather to the colder than to the warmer seasons of the 
year, or when a low dew point indicates that the air has reached a 
perfect state of aqueous solution, as in the case of frosts, &c. 
I have already adverted to the remarkable prevalence of haze in 
the United States, and shall have occasion in the sequel to refer 
to the frequency with which the sky is overcast, sometimes for 
days, nay almost for weeks together.t And though I have 
* I hope I shall not be accused of unfounded insinuations against the honesty of 
the American nation in hinting the possibility of the latter contingency, and so be - 
compelled to take them at their word, and fall back, for my own defence, on the 
rather startling request one finds posted up in every sleeping-room of most hotels in 
that country, ; 
“ Please to lock and bolt your door at night to prevent robbery.” 
I believe there is as much security for property as well as person in the United 
States, as in any country in the world; did our hotels swarm like theirs with 
strangers of all classes, arriving and departing at every moment of the day and 
night, a similar warning to the above would not be unnecessary. 
+ I find, by my journal, that at Philadelphia from the 31st of October to the 
15th of November (inclusive) 1846, the weather was constantly wet or thickly 
