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the river flats there is little else than the Valisneria, the food of the canvas-back duck.
Among the forest trees' may be found about fifteen species of oaks, mostly of the commoner sorts. Those which deserve notice as being scarce are the scrub or bear oak, the laurel oak, and Bartram's oak, or Q. heterophylla; the latter, upon the authority of two observers, being found within a few miles on a northeast line from the city. The chesnut, hickories, black walnut, and but-. ternut, are common. The dwarf pine, Pinus inops, associated with Virginia cedar and sassafras, clothe the barren old fields, giving them an uninviting appearance. But few forest trees of original growth are now seen near the city. In private grounds or parks, on Boundary Street, in Washington, or on Georgetown Heights, may be observed some fine examples of oaks, which are preserved with commendable care.
A few groves of the yellow pine are still standing among the hills, a few miles north of the city, whilst near the river margin may be seen some large specimens of American elm and linden.
On the rocky bluffs on the south side of the river, and above the Aqueduct, we have, in the early Spring, rich masses of color from the red flowers of the Judas tree, the white flowering Amelanchier and dogwood, in contrast with the dark foliage of the surrounding pines and cedars; and, at the water level of the same localities, the witch hazel, or Hammamelis, produces its yellow flowers in the Fall and its fruit in the Spring. Farther up the river, and near the Little Falls Bridge, a single settlement of Rhododendron maximum has been found half buried in the kalmia thickets overhanging the river.
Here we encounter the evidences of the only strange flora which can be said to intrude into our District, most of the species of which can be traced up to the far western sources of the Potomac. They have been observed all over both sides of the river, as high up as the Great Falls, and many of them may be collected at or near High or Rock Island, about a mile above Little Falls Bridge. It will suffice to enumerate a few of the more common, viz.: Opuntia Muscari, Phlox divaricata, Phacelia, two species of Sedum, Dracocephalum, the blue Baptisia; Jeffersonia, Trillium, Asarum, a rare orchid, Tipularia discolor, Erigenia bulbosa, Pentstemon, &c. They are also accompanied by the papaw, Dirca palustris, or leatherwood, Schollera and Lythrum.
Among the ferns we find about twenty species, which are abundant and well grown. The only species that need be mentioned for their scarcity is the Camptosurus, or walking fern, at Cabin John Aqueduct Bridge, and Asplenium augustifolium, at High Island, before referred to.
The temperature of Washington (in the shade) ranges from 105 degrees above to twelve degrees below zero, of Fahrenheit's scale. The mean of January, the coldest month, is about 32°; and of July, the warmest month, about 77o. The mean temperature of the year is about 56°. Sudden changes of temperature are sometimes experienced, the thermometer falling 20 or 30 degrees in a few hours. These changes are not local, but may be traced, in different degrees, over a large extent of country, and come with a west or northwest wind. The river is generally closed in the early part of January, and, in very cold Winters, heavy teams may cross on the ice. Snow rarely falls in sufficient quantities for sleighing, but sometimes admits of that mode of conveyance during several days. The Winter storms come from the west, and are preceded by a northeast wind. The prevailing wind in Winter is from the west or northwest, and in Summer from a southerly quarter. The amount of rain during a year averages about forty inches, the larger portion falling in the Summer months. The range of the barometer is nearly or quite two inches. Vegetation seems to proceed all Winter, and the migratory birds return about the first of April. Fair days are the rule, foul days form the exception, and the bad weather seems generally to commence at 3 o'clock in the afternoon or 4 in the morning.
The average rate of deaths is about one in fifty; but owing to the fact that the corporation of Washington has no power to originate a penal statute, and as Congress has provided no penalty for failures to record births, marriages, and deaths, statistics upon these matters must necessarily be incomplete and unreliable. Owing to the wide streets and numerous open spaces, as well as to natural salubrity, the city and District are almost entirely exempt from“epidemics; the diseases incident to compact and crowded cities are here scarcely known. There are very few deaths from malarious diseases, and the number of these is annually decreasing. A large proportion of the deaths amongst strangers for which the climate of Washington is sometimes held • responsible is to be attributed to two causes,—the entire change of diet and mode of life, by which the constitution is weakened and every lurking disease strengthened, and too frequently the casting away of the moral integrity of home, by which the same result is obtained, and the victim of unu-. sual dissipation is charged to the account of the climate of the seat of government. From the partial returns of the census of 1850, it appears that in a population of 51,687, there were only 846 recorded deaths, which would give the small percentage of 1.64.
From the report of the Commissioner of Health, it appears that during the twelve years commencing July, 1848, and ending July, 1860, the recorded deaths in the City of Washington have been as follows :July 1848 to June 1849,..
1,115 July 1853 to June 1854,.
..1,209 July 1854 to June 1855,.
.1,188 July 1855 to June 1856,.
.1,081 July 1856 to June 1857,.
926 July 1857 to June 1858,.
.1,108 July 1858 to June 1859,.
.937 July 1859 to June 1860,. The greatest number of deaths seems to occur in the months of July and August, but January, February, and March present formidable bills of mortality, probably owing to the vast influx of strangers during the session of Congress.
PROGRESS OF POPULATION.
It must be borne in mind, in connection with the accompanying table showing the progress of population
from 1800 to 1860, that by an act of Congress, dated July 9th, 1846, Alexandria, town and county, was retroceded to Virginia, so that, in computing the progress of population in the District of Columbia up to 1840, the territory including Alexandria (embracing 9,969 inhabitants not since computed) was taken as a basis of calculation.
POPULATION OF THE DISTRICT OF COLUMBIA.
Total Decade. Population.
Increase per cent.
4.04 23.28 21.45 13.61