I shall conclude the account of the influence of the climate of Pennsylvania upon the human body, with the following observations.
1. The sensations of heat and cold are influenced so much by outward circumstances, that we often mistake the degrees of them by neglecting to use such conveniences as are calculated to obviate the effects of their excess. A native of Jamaica often complains less of the heat, and a native of Canada of the cold, in their respective countries, than they do under certain circumstances in Pennsylvania. Even a Pennsylvanian frequently complains less of the heat in Jamaica, and of the cold in Canada, than in his native state. The reason of this is plain. In countries where heat and cold are intense and regular, the inhabitants guard themselves, by accommodating their houses and dresses to each of them. The instability and short duration of excessive heat and cold in Pennsylvania, have unfortunately led its inhabitants, in many instances, to neglect adopting customs, which are used in hot and cold countries to guard against them. Where houses are built with a southern or south-western front exposure, and where other accommodations to the climate are observed in their construction, the disagreeable excesses of heat and cold are rendered much less perceptible in Pennsylvania. Perhaps the application of the principles of philosophy and taste to the construction of our houses, within the last thirty or forty years, may be another reason why some old people have supposed that the degrees of heat and cold are less in Pennsylvania than they were in former years.
2. The variable nature of the climate of Pennsylvania does not render it necessarily unhealthy. Doctor Huxham has taught us, that the healthiest seasons in Great-Britain have often been accompanied by the most variable weather. His words upon this subject convey a reason for the fact. “When the constitutions of the year are frequently changing, so that by the contrast a sort of equilibrium is kept up, and health with it; and that especially if persons are careful to guard themselves well against these sudden changes[36].” Perhaps no climate or country is unhealthy, where men acquire from experience, or tradition, the arts of accommodating themselves to it. The history of all the nations of the world, whether savage, barbarous, or civilized, previously to a mixture of their manners by an intercourse with strangers, seems to favour this opinion. The climate of China appears, in many particulars, to resemble that of Pennsylvania. The Chinese wear loose garments of different lengths, and increase or diminish the number of them, according to the frequent and sudden changes of their weather; hence they have very few acute diseases among them. Those inhabitants of Pennsylvania who have acquired the arts of conforming to the changes and extremes of our weather in dress, diet, and manners, escape most of those acute diseases which are occasioned by the sensible qualities of the air; and faithful inquiries and observations have proved, that they attain to as great ages as the same number of people in any part of the world.
Footnotes:
[30] American Philosophical Transactions, vol. I.
[31] I cannot help agreeing with Mr. Kirwan, in one of his remarks upon the science of meteorology, in the preface to his estimate of the temperature of different latitudes. “This science (says he), if brought to perfection, would enable us at least to foresee those changes in the weather which we could not prevent. Great as is the distance between such knowledge and our own present attainments, we have no reason to think it above the level of the powers of the human mind. The motions of the planets must have appeared as perplexed and intricate to those who first contemplated them; yet, by persevering industry, they are now known to the utmost precision. The present is (as the great Leibnitz expresses it) in every case pregnant with the future, and the connection must be found by long and attentive observation.”
The influence which the perfection of this science must have upon health, agriculture, navigation, and commerce, is too obvious to be mentioned.
[32] The following account of the thaw of the river Susquehannah, in the spring of 1784, was published by the author in the Columbian Magazine, for November, 1786. It may serve to illustrate a fact related formerly in the history of the winters in Pennsylvania, as well as to exhibit an extraordinary instance of the destructive effects of a sudden thaw.
“The winter of 1783-4 was uncommonly cold, insomuch that the mercury in Fahrenheit's thermometer stood several times at 5 degrees below 0. The snows were frequent, and, in many places, from two to three feet deep, during the greatest part of the winter. All the rivers in Pennsylvania were frozen, so as to bear waggons and sleds with immense weights. In the month of January a thaw came on suddenly, which opened our rivers so as to set the ice a-driving, to use the phrase of the country. In the course of one night, during the thaw, the wind shifted suddenly to the north-west, and the weather became intensely cold. The ice, which had floated the day before, was suddenly obstructed; and in the river Susquehannah, the obstructions were formed in those places where the water was most shallow, or where it had been accustomed to fall. This river is several hundred miles in length, and from half a mile to a mile and a half in breadth, and winds through a hilly, and in many places a fertile and highly cultivated country. It has as yet a most difficult communication with our bays and the sea, occasioned by the number and height of the falls which occur near the mouth of the river. The ice in many places, especially where there were falls, formed a kind of dam, of a most stupendous height. About the middle of March our weather moderated, and a thaw became general. The effects of it were remarkable in all our rivers; but in none so much as in the river I have mentioned. I shall therefore endeavour in a few words to describe them. Unfortunately the dams of ice did not give way all at once, nor those which lay nearest to the mouth of the river, first. While the upper dams were set afloat by the warm weather, the lower ones, which were the largest, and in which, of course, the ice was most impacted, remained fixed. In consequence of this, the river rose in a few hours, in many places, above 30 feet, rolling upon its surface large lumps of ice, from 10 to 40 cubic feet in size. The effects of this sudden inundation were terrible. Whole farms were laid under water. Barns, stables, horses, cattle, fences, mills of every kind, and, in one instance, a large stone house, 40 by 30 feet, were carried down the stream. Large trees were torn up by the roots; several small islands, covered with woods, were swept away, and not a vestige of them was left behind. On the barns which preserved their shape, in some instances, for many miles were to be seen living fowls; and, in one dwelling, a candle was seen to burn for some time, after it was swept from its foundation. Where the shore was level, the lumps of ice, and the ruins of houses and farms, were thrown a quarter of a mile from the ordinary height of the river. In some instances, farms were ruined by the mould being swept from them by the cakes of ice, or by depositions of sand; while others were enriched by large depositions of mud. The damage, upon the whole, done to the state of Pennsylvania by this fresh, was very great. In most places it happened in the day time, or the consequences must have been fatal to many thousands.”
“I know of but one use that can be derived from recording the history of this inundation. In case of similar obstructions of rivers, from the causes such as have been described, the terrible effects of their being set in motion by means of a general thaw may in part be obviated, by removing such things out of the course of the water and ice as are within our power; particularly cattle, hay, grain, fences, and farming utensils of all kinds.”