The seasons. Vernal and autumnal equinoxes. Days and nights always equal, if the axis of the earth were perpendicular to the plane of its orbit. Seasons occasioned by the inclination of the earth’s axis. Seasons continued. Days and nights equal at all times under the equator. The sun above the horizon of the poles six months; and six months below them alternately, so that they have but one day and one night in the year; the longest day under the polar circles is twenty-four hours. The sun rises on different points of the compass at different seasons of the year. Twilight in the polar regions of long duration. We are nearest the sun in winter, yet it is our coldest season, why. The earth divided into zones; proved to be globular, but is not a true sphere. DIALOGUE XI. p. 120. The moon. Her diameter, synodical and periodical revolutions. Her phases. Has always the same side to the earth, and makes a revolution on her axis every lunation. Has mountains and valleys, but no seas nor atmosphere; yet may be inhabited. Her real and apparent motion described. Eclipses. Of the sun; total and partial eclipses. Digit, what. Eclipse of the moon. Penumbra, what. Central and total eclipse. Why we have not an eclipse at every full and change of the moon. She does not always rise with the sun at change; nor when he sets at full. She is visible when totally eclipsed. DIALOGUE XII. p. 136. Tides. Occasioned by the attraction of the sun and moon, and their centrifugal forces; exemplified by an experiment. Spring and neap tides. Tides not highest directly under and opposite the moon, but after she has passed the meridian. They are later and later every day. Rule for finding the proportional magnitudes of the planets compared with the earth; or the proportion that one globe bears to another. A cube number, what. Table of roots, squares, and cubes; an example. Rule for finding the mean distances of the planets from the sun. Dr. Turner’s rule for extracting the cube root; an example to explain the rule. Example to find the mean distance of Mercury from the sun. Table of diameters, &c. Conclusion. ------------------------------------------------------------------------ DIALOGUE I.