sun, to feed the flame a single hour. Were the sun a solid body of coal, it would burn up at this rate in forty-six centuries. Sir John Herschel says that if a solid cylinder of ice 45 miles in diameter and 200,000 miles long were plunged, end first, into the

sun, it would melt in a second of time. ()ubtfut

APPARENT SIZE.—It appears to be about a half degree in diameter, so that 360 disks like the sun, laid side by side, would make a half circle of the celestial sphere. It seems a little larger to us in winter than in summer, as we are 3,000,000 miles nearer it. If we represent the luminous surface of the sun when at its average (mean) distance by 1000, the same surface will be represented to us when in aphelion (July) by 940, and when in perihelion (January) by 1072.

DIMENSIONS.-Its diameter is about 850,000 miles.* Let us try to understand this amount by comparison.

A mountain upon the surface of the sun, to bear the same proportion to the globe itself as the Dhawalaghiri of the Himalayas does to the earth, would have to be about six hundred miles high.

Again: Suppose the sun were hollow, and the earth, as in the cut (Fig. 4), placed at the centre, not only would there be room for the moon to revolve in its regular orbit within the shell, but that would stretch off in every direction 200,000 miles beyond. Its volume is 1,245,000 times that of the earth

* Pythagoras, whose theory of the universe was in so many respects very like the one we receive, believed the sun to be 44,000 miles from the earth, and 75 miles in diameter.

i. e., it would take 1,245,000 earths to make a globe the size of the sun. Its mass is 674 times that of all the rest of the solar system. Its weight may be expressed in tons thus,

1,910,278,070,000,000,000,000,000,000,

a number which is meaningless to our imagination, but yet represents a force of attraction which holds our own earth and all the planets steadily in their places; while it fills the mind with an indescribable awe as we think of that Being who made the sun, and holds it in the very palm of his hand.

The density of the sun is only about one-fourth that of the earth, or 1.43 that of water, so that the weight of a body transferred from the earth to the sun would not be increased in proportion to the comparative size of the two. On account also of the vast size of the sun, its surface is so far from its centre that the attraction is largely diminished, since that decreases, we remember, as the square of the distance. However, a man weighing at the earth's equator 150 lbs., at the sun's equator would weigh about 4,080 lbs., a force of attraction that would inevitably and instantly crush him. At the earth's equator a stone falls 16 feet the first second; at the sun's equator it would fall 437 feet.

TELESCOPIC APPEARANCE OF THE SUN: SUN-SPOTS.We may sometimes examine the sun at early morning or late in the afternoon with the naked eye, and at midday by using a smoked glass. The disk will appear to us perfectly distinct and circular, and with no spot to dim its brightness. If we use, however, a telescope of moderate power, taking the precaution to properly shield the eye with a colored eye-piece, we shall find its surface sprinkled with irregular spots, somewhat as shown in the accompanying figure.

Curious opinions concerning solar spots.-The natural purity of the sun seems to have been formerly an article of faith among astronomers, and therefore on no account to be called in question. Scheiner, it is said, having reported to his superior that he had seen spots on the sun's face, was abruptly dis

missed with these remarks: "I have read Aristotle's writings from end to end many times, and I assure you I do not find anything in them similar to that which you mention. Go, my son, tranquillize yourself; be assured that what you take for spots are the faults of your glasses or your own eyes."

Discovery of the solar spots.-They seem to have been noticed as early as 807 A. D., although the telescope was not invented until 1610, and Galileo discovered the solar spots in the following year. We

read in the log-book of the good ship Richard of Arundell, on a voyage, in 1590, to the coast of Guinea, that "on the 7, at the going, downe of the sunne, we saw a great black spot in the sunne; and the 8 day, both at rising and setting, we saw the like, which spot to me seeming was about the bignesse of a shilling, being in 5 degrees of latitude, and still there came a great billow out of the souther board."

Number and location of spots. - Sometimes, but rarely, the disk is clear. During a period of ten years, observations were made on 1982 days, on 372 of which there were no spots seen. As many as two hundred spots have been noticed at one time. They are found in two belts, one on each side of the equator, within not less than 8° nor more than 35° of latitude. They seem to herd together-the length of the straggling group being generally parallel to the equator.

The size of the spots.-It is not uncommon to find a spot with a surface larger than that of the earth. Schröter measured one more than 29,000 miles in diameter. Sir J. W. Herschel calculated that one which he saw was 50,000 miles in diameter. In 1843 one was seen which was 14,816 miles across, and was visible to the naked eye for an entire week. On the day of the eclipse in 1858, a spot over 107,000 miles broad was distinctly seen, and attracted general attention in this country. Some who read this paragraph will doubtless recall its ap