Note: This text has been automatically extracted via Optical Character Recognition (OCR) software.
The Change Of Climate In The Middle Colonies Of North-America.
Perhaps it may be ' npprehended , that as clearing the country will mitigate the cold of our winters , it will also increase the heat of our summers ; but I apprehend that on a careful attention to this subject we shall find , that the same cause will in those seasons appear to produce different effects , and that instead of more heat , we shall presently have less in summer than usual . It is well known that during the greatest summer heats of this or
any other country , the extraordinary heat of theatrnosphere does not rise to any considerable height . In the upper regions it is perpetuall y cold , ' because the air in those parts is too far from the earth to be warmed by the heat of its surface , and because the air in those regions not being pressed by such a weig ht of incumbent atmosphere , is too rare to be susceptible of a great degree of heat ; for the heat
of the air , as of every other body that is warmed by the sun , depends not only upon the simple aftion of the particles of light upon those of the air , but also upon the mutual action of the particles of air upon one another , which , by their elasticity , propagate or continue that motion , called heat , which was originally excited by 'the sun ' s rays . Therefore , the rarer the atmosphere is , the less heat will observe
be produced therein by the sun , and vice versa . Hence we , that in the warmest countries the tops of mountains are always covered with snow . Whoever will carry a thermometer on a very warm day to the top of an hig h steeple , will find that the mercury immediately falls several degrees , and rises again as he descends . From this it is obvious that nothing is wanting in the midst of summer to render the country agreeably cool , but a proper mixture of the cold air which is above with the warm air below . This would be
effected by any cause that mig ht encrease our summer winds . For though the simple motion ofthe air does not by any means produce cold , yet moderate blasts will naturally introduce a colder atmosphere , especially when they pass over hills or any unequal surface , by which the equilibrium ofthe atmosphere is destroyed , the- cold air always ten'ding towards the surface . Hence a summer ' s gust is generally attended ba sudden change in the temperature of the air . Tall
y timber greatly impedes the circulation of the air , for it retards the motion of that part which is near the surface , and which , from its density and situation being most heated , becomes the general origin of such agitations as take place in the upper regions . We shall often find it extremely sultry and warm in a small field , surrounded by tall woods , when no such inconveniency is perceived on an extensive
clear . plain in the neighbourhood . From these particulars we may conclude , that when this country shall be diversified , as it must be in a series of years , by vast tracts of clear land , intersected here and there by great " ridges of uncultivated mountains , a much greater degree of heat being reflected by the plains than from the neighbouring mountainsand an easycirculation of air produced on the
plains—, , our land winds in summer , to say nothing of those whichcome from the sea , or from the lakes , must certainly be much fresher and more frequent than they now are , and consequently our summer heats be more temperate .
Note: This text has been automatically extracted via Optical Character Recognition (OCR) software.
The Change Of Climate In The Middle Colonies Of North-America.
Perhaps it may be ' npprehended , that as clearing the country will mitigate the cold of our winters , it will also increase the heat of our summers ; but I apprehend that on a careful attention to this subject we shall find , that the same cause will in those seasons appear to produce different effects , and that instead of more heat , we shall presently have less in summer than usual . It is well known that during the greatest summer heats of this or
any other country , the extraordinary heat of theatrnosphere does not rise to any considerable height . In the upper regions it is perpetuall y cold , ' because the air in those parts is too far from the earth to be warmed by the heat of its surface , and because the air in those regions not being pressed by such a weig ht of incumbent atmosphere , is too rare to be susceptible of a great degree of heat ; for the heat
of the air , as of every other body that is warmed by the sun , depends not only upon the simple aftion of the particles of light upon those of the air , but also upon the mutual action of the particles of air upon one another , which , by their elasticity , propagate or continue that motion , called heat , which was originally excited by 'the sun ' s rays . Therefore , the rarer the atmosphere is , the less heat will observe
be produced therein by the sun , and vice versa . Hence we , that in the warmest countries the tops of mountains are always covered with snow . Whoever will carry a thermometer on a very warm day to the top of an hig h steeple , will find that the mercury immediately falls several degrees , and rises again as he descends . From this it is obvious that nothing is wanting in the midst of summer to render the country agreeably cool , but a proper mixture of the cold air which is above with the warm air below . This would be
effected by any cause that mig ht encrease our summer winds . For though the simple motion ofthe air does not by any means produce cold , yet moderate blasts will naturally introduce a colder atmosphere , especially when they pass over hills or any unequal surface , by which the equilibrium ofthe atmosphere is destroyed , the- cold air always ten'ding towards the surface . Hence a summer ' s gust is generally attended ba sudden change in the temperature of the air . Tall
y timber greatly impedes the circulation of the air , for it retards the motion of that part which is near the surface , and which , from its density and situation being most heated , becomes the general origin of such agitations as take place in the upper regions . We shall often find it extremely sultry and warm in a small field , surrounded by tall woods , when no such inconveniency is perceived on an extensive
clear . plain in the neighbourhood . From these particulars we may conclude , that when this country shall be diversified , as it must be in a series of years , by vast tracts of clear land , intersected here and there by great " ridges of uncultivated mountains , a much greater degree of heat being reflected by the plains than from the neighbouring mountainsand an easycirculation of air produced on the
plains—, , our land winds in summer , to say nothing of those whichcome from the sea , or from the lakes , must certainly be much fresher and more frequent than they now are , and consequently our summer heats be more temperate .