152 BOTANY OF THE 
t 
the sun, and effectually veiling all objects at even a moderate dis- 
tance from the observer. It is said to prevail more in the spring 
and fall than at any other time of the year; but during the twelve 
months I passed in America, it was of continual recurrence at 
short but uncertain intervals, in all parts of the country, and at 
every season alike. From the 30th of June last till the 16th of 
July inclusive, which I spent in Massachusetts, and principally at 
Boston, “smoky " weather prevailed for about half the number of 
days comprised in that period, sometimes so dense as to approxi- 
mate in opacity to the atmosphere of the heart of London, and —— 
provokinghy to shut out all view of the pretty landscape around. — | 
This was especially and inopportunely the case on the 16th, when — 
T left in the steamer for England, at which time the fine scenery — 
of Boston Harbour was invisible from her crowded deck. 1 wit- 
nessed this phenomenon in singular intensity at Savannah two 
months before. I shall have occasion to mention it hereafter, and 
will now only refer the reader to the details, given by Mr. Thompson —— 
in his very curious and amusing History of Vermont,* of this — 
smoky state of atmosphere, and the extraordinary darkness it has 
sometimes occasioned, approaching at midday to that of might, so 
that a book of ordinary print could not be read by the sun’s light. 
Aug. 6th.—Started this morning by the “ accommodation (rail- 
way) cars” for West Chester, a borough thirty-one miles due west 
of Philadelphia, the capital of Chester County, and the residence of ; 
Dr. Darlington, well known for his valuable contributions to Ameri- — 
can Botany, and his admirable illustrations of the plants of Chester — 
= County, first published in the form of a Catalogue,t and subse- —— 
_ quently expanded into a descriptive Flora of the district of Penn- — 
sylvania:f a work, which for clearness of definition, originality im — 
execution, and accuracy of description, has few equals in either — 
hemisphere amongst compositions of this class, for which, in these 
and some other respects, it may well furnish a model. To this - 
* History of Vermont, Natural, Civil, and Statistical, by Zadock Thompsom 
.. Burlington, Vermont, 1842, 8vo. | ee 
+ Florula Cestrica. W. Chester. 1826. 8vo. 
AE + Flora Cestrica. W. Chester. 1837. 8vo. 
