115. * Degrees of longitude may be turned into time by multiplying by 4; observing that minutes or miles of longitude produce seconds of time, when multiplied by 4, and degrees of longitude, when multiplied by 4, produce minutes of

time.

116.

Time may be reduced into degrees, &c. by multiplying them by 10, and increasing the product one half.

117. Apparent noon is the time when the sun comes to the Meridian, viz. 12 o'clock, as shewn by a correct sun dial.

118. True or mean noon is 12 o'clock, as shewn by a well regulated clock, adjusted to go twentyfour hours in a mean solar day.

119. The equation of time at noon is the interval between the true and apparent noon; it is the difference of time shewn by a well regulated clock and a correct sun dial.

120. A true solar day is the time from the sun's leaving the meridian of any place, on any day, till it returns to the same meridian on the next day, viz. it is the time elapsed from 12 o'clock at noon, on any day, to 12 at noon, on the next day, as shewn by a correct sun dial.

121. A mean solar day is measured by equal motion, as by a clock or time piece, and consists of twenty-four hours.

122. An astronomical day consists of twentyfour hours, being reckoned from noon to noon.

123. The Artificial day is the time elapsed between the sun's rising' and setting, and is variable according to the different latitudes of places.

124. The civil day, like the astronomical day, consists of twenty-four hours, but begins differently in different nations.

125. The siderjal day is the interval of time from the apparent passage of any fixed star over the meridian, till it returns again; or it is the time which the earth takes to revolve once round its axis, and consists of twenty-three hours, fiftysix minutes, four seconds..

126. A solar or tropical year is the time the sun takes in passing through the ecliptic, from one tropic or equinox, till it returns to it again, and consists of three hundred and sixty five days, five hours, forty-eight minutes, forty-eight seconds.

127. A siderial year is the space of time which the sun takes in passing from one fixed star, till he returns to it again, and consists of three hundred and sixty-five days, six hours, nine minutes, and twelve seconds.

128. The siderial year is twenty minutes, twenty-four seconds longer than the solar year, and the sun returns to the equinox every year before he returns to the same point of the heavens; consequently the equinoctial points have a retrogade motion.

129. The precession (or more properly the recession) of the equinoxes is a slow motion of the equinoctial points from east to west, contrary to the order of the signs."

130. The retrogade motion of the equinoctial points is about 50 seconds in a year, so that it would require 25,791 years for the equinoctial points to perform an entire revolution westward,

round the globe. This period the ancients called the Platonic or great year; and imagined that at its completion every thing would begin as at first, and all things come round in the same order as they had done before.

131. Positions of the sphere are three-right, parallel, and oblique.

132. A right sphere is that position of the earth in which the equator passes through the zenith and nadir, the poles being in the rational horizon.

133. A right sphere is so called because all the parallels of latitude cut the horizon at right angles, and the horizon divides them into two equal parts, making equal day and night. The inhabitants who have this position of the sphere, live at the equator.

134. A parallel sphere is the position of the earth when the rational horizon coincides with the equator, the poles being in the zenith and nadir.

135. A parallel sphere is so called, because all the parallels of latitude are parallel to the horizon, with which the equator coincides. The inhabitants who have this sphere, (if there be any such inhabitants,) live at the poles, and see the sun above their horizon for six months together.

136. An oblique sphere is the position which the earth has when the rational horizon cuts the equator obliquely. This sphere is common to all the inhabitants of the earth, who do not live exactly at the equator or the poles.

137. Climate is part of the surface of the earth, contained between two small circles parallel to the equator, and of such a breadth, that the longest day in the parallel nearest to the pole exceeds the parallel next to the equator, half an hour in the torrid and temperate zones, or one month in the frigid zones.

138. There are twenty-four climates between the equator and each polar circle, and six climates between each polar circle and its pole.*

139. A zone is a portion of the surface of the earth, contained between two small circles parallel to the equator. There are five zones-one torrid, two temperate, and two frigid zones.-[Fig. 2.]

140. The torrid zone extends from the tropic of Cancer to the tropic of Capricorn, and is 46° 56' broad. The equator is in the middle of this zone, from which each tropic is distant 23° 28'. This zone was thought by the ancients to be uninhabitable, because it is exposed.continually to the direct rays of the sun.

141. The two temperate zones. The north temperate zone extends from the tropic of Cancer to the arctic circle, and the south temperate zone, from the tropic of Capricorn to the antarctic circle.-[Fig. 2]

142. The temperate zones are each 43° 4' broad, and were called temperate by the ancients, because, by meeting the sun's rays obliquely, they enjoy a moderate degree of heat.

143. The two frigid zones. The north frigid zone, or rather segment of a sphere, is bounded

From this technical definition of climate, we must not infer that all places situated in the same parallel of latitude, have the same atmospherical temperature. For instance, in Canada, in about the latitude of Paris, and the south of England, the cold is so excessive that the greatest rivers are frozen over from December to April, and the snow commonly lies from four to six feet deep; but the temperature of the atmosphere in the same latitudes, in France and Great Britain, is comparatively warm and mild. The Andes mountains, though part of them are situated in the torrid zone, are, at their summits, covered with snow, which cools the air of the adjacent countries. The heat on the western coast of Africa, after the wind has passed over the sandy desert, is almost suffocating; whilst the same wind, having passed over the Atlantic ocean, is cool and refreshing to the inhabitants of the Carribbean islands.

by the arctic circle. The north pole, which is situated in the middle of this zone, is 23° 28′ from the arctic circle.-[Fig. 2.]

144. The south frigid zone is bounded by the antarctic circle, distant. 23° 28′ from the south pole, which is situated in the centre of this zone.

145. The ancients supposed the frigid zones uninhabited on account of the extreme cold which prevailed in them. They believed that the temperate zones were the only habitable parts of the earth.

146. Amphicii are the inhabitants of the torrid zone, so called because they cast their shadows both north and south, at different times of the year; the sun being north of them at noon, when it has north declination, and then they cast their shadows south; when the sun has south declination, they cast their shadows north.

147. When the sun is vertical, or in the zenith, to the inhabitants of any place in the torrid zone, they have no shadow, and are called Ascii, or shadowless.

148. Heteroscii is the name given to the inhabitants of the temperate zones, because they cast their shadows, at noon, only one way. Thus, the shadow of an inhabitant of the north temperate zone always falls to the north at noon, because the sun is then directly south; and an inhabitant of the south temperate zone casts his shadow south, because the sun is due north at that time.

149. Perisci are the people who inhabit the frigid zones, so called, because their shadows, during a revolution of the earth on its axis, are directed towards every point of the compass. In the frigid zones, the sun does not set during several revolutions of the earth upon its axis.

150. Antoeci are those who live in the same degree of Longitude, and in equal degrees of lat