Imágenes de página
PDF

Air, and change the Air various Ways, and excite Vapours in it, as Astrologers tell us.

6. THE Kinds of the Earth that are in several Places ; for where the Earth is rocky or stony, there the Air is for the most part colder than where ?ris fat and sulphureous, and not so fertile ; or where there is much Sand and no Rivers there is much Heat and Drought.

7. ADJACENT Seas or Lakes ; from thence : come a great many moist Vapours into the Air ; and the Rays are not so strongly reflected from the Sea as from the Land.

8. THE Situation of Places; for the Sun influ. ences the Mountains and Vallies differently, and the Rays are kept from the Plains oftentimes by the Mountains, which do alfo in fome manner draw the Vapours to them, as we faid Chap. 20. Whence 'tis the Mountains change the Seasons of the neighbouring Places ; caufing Heat, Rain, &c. which would not be if the Mountains were not there. ; 9. THE Winds, especially the general, and stated ones ; thus the stated easterly Winds temper the Heat of the Dog-Days, and the general Wind in the Torrid Zone, especially the East Winds in Brail cause a moderate Heat there: whilft there is a vehement Heat in the West of Africa ; for in theie Places the general Wind is not fo- sensible. The North Winds are cold and dry. The South Winds are hot and moist with us. · 10. THE Clouds and Rain lessen the Light and Heat. : THESE are, I fuppofe, all the Causes of the Changes that happen as to Light, Heat, &c. either in the fame, or different Places, at different, or che fume times.

PROPOS Ć PROPOSITION II. How the Seasons of the Year, as Spring, Summer, : Autumn, and Winter are to be defined." PROPOSITION III.

:: ALTHO! we are not, in treating of the Sciences, to dispute about the Definitions of things ; yet, becaufe the Signification of fome Words is dubious; we must explain them here, to avoid Confusion, and that Students may not be entan.' gled and deceived with different Meanings.' : ? THE Queftion includes two Difficulties ; 1. Whether the Seafons are determined by the Sun's Entrance into, and continuing in, certain Signs of the Ecliptic, as Astronomers generally suppose, calling it Spring when the Sun enters the first of Aries, which continues ’till it enters the first of Cancer , and making ic Summer 'till the Sun moves from that to the first of Libra; and Autumn 'till it come to the first of Capricorns and Winter 'till it come to the first of Aries again."'' ? 'TIS evident that these Definitions are not true in all Places, but only in those to the North of the Equator ; for in the South Places they have Spring while the Sun is between the first of Libra, and the first of Capricorn, and Summer from that to the first of Aries; and fo on the contrary to the former : and one may think the Seafons cannot be explained in a Sense agreeable to all Places, and yer they may and qught to be. Moreover, the Definitions above do not agree to Places in the Torrid Zone; for when the Sun passes over them iç must be allowed to be Summer there (except fome other Cause alter it); with respect to the Heavens, and in Places on the Equator, it oughe not to be either Spring or Autumn when the Sun is past the first of Aries, but Summer, for then the Sun is passing

over them, and so making the greatest Heat to them : nor can that Summer be transferred to the first of Cancer, or Capricorn. And the same may be said of Places between the Equator and Tropics, because the Sun passes over them also before it comes to the first of Cancer or Capricorn, and fa makes Summer first. For it must be known, that tho' Definitions are arbitrary, yet all agree in making the Summer to be caused by Heat, and the Winter by Cold, or less Heat; and Definitions ; must be so framed, as to agree in part with these Notions, or not to be repugnant to them ; and there is the same Difficulty as to Spring and Autumn in the Torrid Zone ; whilst there seems to be none at all, especially at the Equator. . . .

THE fecond Difficulty which made the Ques, stion be proposed is, whether, the Seasons are to be determined from the Degree of Heat and Cold, or from the Sun's, approaching, or withdrawing 2 for the common Notion of the Europeans of the Seafons includes thein both, especially the Cold and Heat, tho' Astronomers have most regard to the Şun's Place in the Ecliptic. Moreover, ?ris found in many Places in the Torrid Zone, that the Seasons do not answer the Sun's coming to them, or go ing from them, but that they find it Winter (abounding not indeed with Cold, but with Rains and Storms) when it should be Summer, by the Sun's being nearly above them; and on the contrary, they find it Summer when the Sun goes from them, and they fhould rather have Winters of which strange thing we fhall give Examples afterwards. And therefore they make their Summer to conøft in a clear Sky ; and their Winter in wet Weather, with a little Cold. And therefore the Notions of the Seasons differ' much according to the Places.

AFTER

[ocr errors]

The celestial Summer of those Places between the North

Tropic, and the North Pole, begins when the Sun enters the first of Cancer, on the twenty first of June, and ends, when it enters the first of Libra, on the twenty first of September ; and at the same Time in all those Places. And 'tis Autumn with them when the sun goes from the first of Libra to the first of Capricorn, and Winter while 'tis between the first of Capricorn, and the first of Aries,

THE Truth of this Proposition appears from the foresaid Definitions, and may be easily shown on the Globe and Maps ; for the Sun is least distant from the Zenith when in the Tropic of Cancer ; and is at a mean Distance when between the first of Libra and Capricorn. :

THE Summer Places between the South Tropic and the Pole, which takes in the Temperate and the Frigid Zone, begins when the Sun enters the first of Capricorn, and ends when it enters the first of Aries; and their Autumn is between the first of Aries, and the first of Cancer ; and the Winter between that, and the first of Libra ;, and between that, and Capricorn is their Spring.

THIS may be shown the same way as the former. · THE Seasons in the Torrid Zone do not begin in all Places at the same time. 1. Those under the Equator have this peculiar to them, that they have two Summers, two Winters, and as many Springs and Autumns, and that each Year ; so that between the twenty first of March, and the twen. ty first of September they have, or should have by the Sun's Course all the four Seasons ; and the

same

« AnteriorContinuar »