Читать книгу A New Guide for Emigrants to the West - John Mason Peck - Страница 14

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Comparative view of the Climate with the Atlantic States. Diseases.—Means of preserving health.

Climate, &c. In a country of such vast extent, through 15° of latitude, the climate must necessarily be various. Louisiana, Mississippi and the lower half of Arkansas, lie between the latitudes of 30° and 35°, and correspond with Georgia and South Carolina. Their difference of climate is not material. The northern half of Arkansas, Tennessee and Kentucky, lie west from North Carolina and the southern portion of Virginia. The climate varies from those states only as they are less elevated than the mountainous parts of Virginia and Carolina. Hence, the emigrant from the southern Atlantic states, unless he comes from a mountainous region, will experience no great change of climate, by emigrating to the Lower Mississippi Valley. Missouri, Illinois, Indiana and Ohio, lie parallel with the northern half of Virginia, Maryland, Delaware, Pennsylvania, New Jersey, and so much of New York and New England as lies south of the 42° of north latitude. But several circumstances combine to produce variations in the climate.

1. Much of those Atlantic states are hilly, and in many parts mountainous, some of which are 2 and 3000 feet above the level of the ocean. The parallel western states have no mountains, and are not proportionably hilly.

2. The Atlantic states border on the ocean on the east, and feel the influence of the cold, damp winds from the northeast and east. Their rains are more copious and their snows deeper. The northern portions of the West, equally with New York and Vermont, are affected with the influence of the lakes, though not to the same extent.

5. "The courses of rivers, by changing in some degree the direction of the winds, exert an influence on the climate. In the Atlantic states, from New England to North Carolina, the rivers run more or less to the southeast, and increase the winds which blow from the northwest, while the great bed of the Mississippi exerts an equal influence in augmenting the number and steadiness of the winds which blow over it from the southwest; and there is another cause of difference in climate, chiefly perceptible, first, in the temperature, which, if no counteracting cause existed, they would raise in the west considerably above that of corresponding latitudes in the east; and, secondly, in the moisture of the two regions, which is generally greater west than east of the mountains, when the southwest wind prevails; as, much of the water with which it comes charged from the Gulf of Mexico, is deposited before it reaches the country east of the Alleghanies."—Dr. Drake.

It is an error that our climate is more variable, or the summers materially hotter, than in a correspondent latitude in the Atlantic states. "The New Englander and New Yorker north of the mountains of West Point, should bear in mind that his migration is not to the West but South West; and as necessarily brings him into a warmer climate, as when he seeks the shores of the Delaware, Potomac, or James' River."

The settlers from Virginia to Kentucky, or those from Maryland and Pennsylvania to Ohio, or further west, have never complained of hotter summers than they had found in the land from whence they came.

To institute a comparative estimate of temperature between the east and the west, we must observe: first, the thermometer; and, secondly, the flowering of trees, the putting forth of vegetation, and the ripening of fruits and grain in correspondent latitudes. This has not usually been done. Philadelphia and Cincinnati approach nearer to the same parallel, than any other places where such observations have been made. Cincinnati, however, is about 50' south of Philadelphia. The following remarks are from Dr. Daniel Drake of Cincinnati, to whose pen the west is much indebted.

"From a series of daily observations in Cincinnati or its vicinity, for eight consecutive years, the mean annual temperature has been ascertained to be 54 degrees and a quarter. Dr. Rush states the mean temperature of Philadelphia at 52 degrees and a half; Dr. Coxe, from six years' observations, at 54° and a sixth; and Mr. Legaux, from seventeen years' observations, at Spring Mill, a few miles out of the city, at 53° and a third; the mean term of which results, 53° and a third, is but the fraction of a degree lower than the mean heat of Cincinnati, and actually less than should be afforded by the difference of latitude.

"A reference to the temperatures of summer and winter, will give nearly the same results. From nine years' observations, (three at Spring Mill, by Mr. Legaux, and six in Philadelphia, by Dr. Coxe,) the mean summer heat of that part of Pennsylvania, appears to be 76 degrees and six-tenths. The mean summer heat at Cincinnati, for an equal number of years, was 74 degrees and four-tenths. The average number of days in which the thermometer rose to 90 degrees or upwards, during the same period, was fourteen each summer; and the greatest elevation observed was 98 degrees: all of which would bear an almost exact comparison with similar observations in Pennsylvania. Mr. Legaux states the most intense cold, at Spring Mill, from 1787 to 1806, to have been 17 and five-tenths degrees below cipher—while within the same period it was 18° at Cincinnati. The average of extreme cold for several years, as observed by Mr. Legaux, was one and eight-tenths of a degree below cipher:—the same average at Cincinnati, was two degrees below. From all which we may conclude, that the banks of the Delaware and Ohio, in the same latitudes, have nearly the same temperature."

The state of Illinois, extending as it does through five and a half degrees of latitude, has considerable variation in its climate. It has no mountains, and though undulating, it cannot be called hilly. Its extensive prairies, and level surface, give greater scope to the winds, especially in winter. In the southern part of the State, during the three winter months, snow frequently falls, but seldom lies long. In the northern part, the winters are as cold, but not so much snow falls, as in the same latitudes in the Atlantic States.

The Mississippi at St. Louis is frequently frozen over, and is crossed on the ice, and occasionally for several weeks. The hot season is longer, though not more intense, than occasionally for a day or two in New England.

During the years 1817–18-19, the Rev. Mr. Giddings, at St. Louis, made a series of observations upon Fahrenheit's thermometer.