[Illustration] Midwinter is over. According to astronomical reckoning, we have just passed that point in the earth’s orbit, where the north pole is turned most from the sun. This position is represented in the diagram above, by the direction of the terminator, or boundary line of light and darkness, which is seen to divide the globe into two equal parts; the north pole, which is the upper pole in the figure, and all parts within 32½ degrees, being enveloped in constant darkness. We now trace the sun among the stars of the constellation Capricorn or sea-goat, and it is winter in the whole northern hemisphere. At the beginning of January the earth is at its _least_ distance from the sun, which is proved by measuring the apparent magnitude of that luminary by means of an instrument called a micrometer, his disc being now about 32 minutes of a degree; whereas at the opposite season, or at the beginning of July, near our Midsummer, his apparent diameter is only about 31 minutes. The coldness of winter therefore does not depend on the distance of the earth from the sun, but on the very oblique or slanting direction of his rays; less heat falling on any given part of the earth, than when the rays fall more direct. From the slanting direction of his rays they pass through a more dense region of the atmosphere, and are somewhat intercepted; while another cause of the cold is the shortness of our days and the length of our nights; the sun continuing only about seven hours and a half above the horizon, while he is absent for about sixteen hours and a half. This position of the earth relatively to the sun is exemplified in the Popular Lectures on Astronomy, now delivering at the Assembly-room, Paul’s Head, Cateaton-street, by Mr. John Wallis, on _Tuesday_ and _Thursday_ evenings. His explanations of this noble science are familiarly and beautifully illustrated, by an original and splendid apparatus devised and constructed by his own hands. It consists of extensive mechanism and numerous brilliant transparencies. Mr. Wallis’s lectures on _Tuesday_ and _Thursday_ next, the 18th and 20th of January, 1825, are under the patronage of the Lord Mayor. Here is a sure mode of acquiring astronomical knowledge, accompanied by the delightful gratification of witnessing a display of the heavens more bewitching than the mind can conceive. Ladies, and young persons especially, have a delightful opportunity of being agreeably entertained by the novelty and beauty of the exhibition and the eloquent descriptions of the enlightened lecturer. * * * * *