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

6. THE Kinds of the Earth that are in feveral Places; for where the Earth is rocky or ftony, there the Air is for the moft Part colder than where 'tis fat and fulphureous, and not fo 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 moift Vapours into the Air ; and the Rays are not fo ftrongly reflected from the Sea as from the Land.

8. THE Situation of Places; for the Sun influences 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 Seafons of the neighbouring Places; caufing Heat, Rain, &c. which would not be if the Mountains were not there.

9. THE Winds, efpecially the general and ftated ones; thus the ftated eafterly Winds temper the Heat of the Dog-Days, and the general Wind in the Torrid Zone, especially the Eaft Winds in Brafil cause a moderate Heat there: whilft there is a vehement Heat in the Weft of Africa; for in thefe Places the general Wind is not fo fenfible. The North Winds are cold and dry. The South Winds are hot and moift with us.

10. THE Clouds and Rain leffen 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 the fame times.·

PROPO

PROPOSITION II.

How the Seafons of the Year, as Spring, Summer, Autumn, and Winter are to be defined.

ALTHO' we are not, in treating of the Sciences, to difpute about the Definitions of things; yet, because the Signification of fome Words is dubious we must explain them here, to avoid Confufiony 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 Aftronomers generally fuppofe, calling it Spring when the Sun enters the first of Aries, which continues 'till it enters the firft of Cancer, and making it Summer 'till the Sun moves from that to the firft of Libra; and Autumn 'till it come to the first of Capricorn and Winter 'till it come to the first of Aries again.

'TIS evident that thefe 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 firft of Libra, and the firft of Capricorn, and Summer from that to the firft of Aries; and fo on the contrary to the former : and one may think the Seafons cannot be explained in a Senfe agreeable to all Places, and yet they may and ought to be. Moreover, the Definitions above do not agree to Places in the Torrid Zone; for when the Sun paffes over them it must be allowed to be Summer there (except fome other Caufe alter it); with refpect to the Heavens, and in Places on the Equator, it ought not to be either Spring or Autumn when the Sun is past the first of Aries, but Summer, for then the Sun is paffing

over them, and fo making the greatest Heat to them: nor can that Summer be transferred to the first of Cancer, or Capricorn. And the fame may be faid of Places between the Equator and Tropics, because the Sun paffes over them alfo before it comes to the first of Cancer or Capricorn, and fo makes Summer firft. 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 lefs Heat; and Definitions must be fo framed, as to agree in part with these Notions, or not to be repugnant to them; and there is the fame Difficulty as to Spring and Autumn in the Torrid Zone; whilft there feems to be none at all, especially at the Equator.

THE fecond Difficulty which made the Queftion be propofed is, whether the Seafons are to be: determined from the Degree of Heat and Cold, or from the Sun's approaching, or withdrawing? for the common Notion of the Europeans of the Seafons includes them both, especially the Cold and Heat, tho' Aftronomers have moft regard to the Sun's Place in the Ecliptic. Moreover, 'tis found in many Places in the Torrid Zone, that the Seasons do not answer the Sun's coming to them, or going from them, but that they find it Winter (a bounding 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 should rather have Winter of which strange thing we fhall give Examples afterwards. And therefore they make their Summer to confift in a clear Sky; and their Winter in wet Weather, with a little Cold. And therefore the Notions of the Seafons differ much according to the Places.

.

AFTER

AFTER confidering thefe Difficulties, I am of Opinion 1. feeing in feveral Places of the Torrid Żone, as was faid in the fecond Difficulty, and alfo in fome Places in the Temperate Zone, Heat and Cold have no regard to the Sun's Motion; nor are we to think that Heat and Cold makes the Seafons, except we diftinguish between Seafons of the Heavens and of the Earth; which Words we must ufe for want of better; hence the terreftrial Summer Seafon of a Place, is the Time of Year when there is greatest Heat there; but the celestial Summer is the Time when one might expect the greatest Heat from the Sun's nearnefs; and the like may be faid of the Winter Seafon : and tho' in feveral Places the celeftial and terreftrial Summer and Winter happen at one Time of the Year; yet in fome Places of the Torrid Zone they are in different Times of the Year, as fhall be showed hereafter. And the fame is to be faid as to the celestial and terreftrial Spring and Autumn.

2. SEEING there are but few Places where the terreftrial Summer and Winter differ from the celeftial, as to the time of Year, they happening in most Places at the fame time of the Year; therefore the celeftial Summer may be called fimply the Summer, and fo the terreftrial Spring, the Spring, &c. and when we would fpeak of the terreftrial Sum-. mer or Winter we fhall call them Terreftrial, to distinguish them from thofe abfolutely called Summer and Winter, when the Celestial and Terrestrial agree.

THE celeftial Summer of a Place is when the Sun comes neareft to it's Zenith; and Winter when furtheft from it; and Spring is between the end of Winter, and beginning of Summer; and Autumn between the end of Summer and beginning of Winter. And these four Seasons may be thus understood in all Places,

PROPO

PROPOSITION III.

The celestial Summer of thofe 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 fame Time in all thofe 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 Propofition appears from the forefaid Definitions, and may be eafily fhown on the Globe and Maps; for the Sun is leaft distant from the Zenith when in the Tropic of Cancer; and is at a mean Distance when between the firft 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 firft of Capricorn, and ends when it enters the firft of Aries; and their Autumn is between the firft of Aries, and the firft 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 fame way as the

former.

THE Seasons in the Torrid Zone do not begin in all Places at the fame 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; fo that between the twenty firft of March, and the twenty first of September they have, or should have by the Sun's Course all the four Seasons; and the

fame