Eclipse
2 of the 7 encyclopedias on this shelf carry an entry for Eclipse. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
an interception or obscuration of the light of the sun, moon or other heavenly body by the intervention of another and non-luminous heavenly body by or its shadow. An eclipse of a star or planet is called may be divided into three classes: solar, occultation. Eclipses lunar, and planetary. Solar Eclipses. An eclipse of the sun is an occultation of part of the face of the moon between the earth and the sun; the sun, occasioned by an interposition of thus all eclipses of the sun happen at the time of the new moon. The dark or central part of the moon's shadow, where the sun's rays are wholly intercepted, is called the umbra, and the light part, where only a part of them are intercepted, is called the penumbra; and it is evident that if a spectator be situated on that part of the earth where the umbra falls, there will be a total eclipse of the sun at that place; in the penumbra there will be no eclipse. As the earth is not always at the same distance from the moon, if the earth is so far from the moon that an eclipse should happen when the rays of light proceeding from the upper and lower limbs of the sun across each other before they reach the earth, a spectator situated on the earth in a direct line between the centers of the sun and moon, would see a ring of light around the dark body of the moon; such an eclipse is called annular; when this happens there can be no total eclipse anywhere, because the moon's umbra does not reach the earth. People situated in the penumbra will perceive a partial eclipse; an eclipse can never be annular longer than 12 minutes 24 seconds, nor total longer than 7 minutes 58 seconds; nor can the duration of any eclipse of the sun exceed two hours. An eclipse of the sun begins on the W. side of his disk and ends on the E.; and an eclipse of the moon begins on the eastern 30-Vol. IIІ-Cyc side of her disk and ends on the western. The average number of eclipses in a year is four, two of the sun and two of the moon; and as the sun and moon are as long below the horizon of any particular place as they are above it, the average number of visible eclipses in a year is two, one of the sun and one of the moon. Total eclipses of the sun offer brief but intensely interesting phenomena for the astronomer's study. The nature of the sun's corona is as yet undetermined, and the aid of the spectroscope and of photography has not been sufficiently applied to the settling of the various problems presented. There were solar eclipses May 18, 1901, Aug. 30, 1905, Aug. 21, 1914, June 8, 1918, May 29, 1919. Lunar Eclipses. An eclipse of the moon is an obscuration of the light of the EARTH SUN PLANE OF THE A ECLIPTIC PLANE OF THE ECLIPTIC SUN ↓ B ECLIPSE A. Eclipse of the moon moon occasioned by an interposition of the earth between the sun and the moon; consequently, all eclipses of the moon happen at full moon; for it is only when the moon is on that side of the earth which is turned away from the sun, and directly opposite, that it can come within the earth's shadow. Further, the moon must at that time be at the same time in the same plane as the earth's shadow; that is, the plane of the ecliptic in which the latter always moves. But as the moon's orbit makes an angle of more than 5° with the plane of the ecliptic, it frequently happens that, though the moon is in opposition, it does not come within the shadow of the earth. Planetary Eclipses. The eclipse of a satellite takes place when the shadow of the primary obscures it. Jupiter offers the most favorable field for observation of this phenomenon. Such eclipses were ÉCOLE POLYTECHNIQUE formerly used to determine longitudes since they are the same viewed from all parts of the earth. The dates of a number of important events of antiquity have been approximately determined by calculations concerning eclipses recorded at or near the time. Eclipses have been calculated up to the year 2161. ÉCOLE DES BEAUX ARTS (ā-kol da bo zär) (School of Fine Arts), the French Government school in Paris, founded by Mazarin in 1648, and provided with an extensive staff of teachers. The competitions for the grands prix de Rome take place at this school. All artists between the age of 15 and 25, whether pupils of this school or not, may compete, after passing two preliminary examinations. The successful compet- MOONS PENUMBRA PENUMBRA ORBIT MOONS EARTH B. Eclipse of the sun itors receive an annual allowance from the state for three or four years, two of The which must be passed at Rome. school has about 2,000 students enrolled, and about 50 instructors. ÉCOLE POLYTECHNIQUE (pol-itek-nēk') (Polytechnic School), a school in Paris established with the purpose of giving instruction in matters connected with the various branches of the , roads and public service, such as mines and the bridges, engineering, the army navy, government manufactures, etc. It was founded in 1794, and is under the direction of the Minister of War. Candidates are admitted only by competitive examination, and have to pay for their board (about $200 a year). The pupils who pass satisfactory examinations at the end of their course are admitted to that branch of public service which they select.
Aiton's Encyclopedia (1910)
e-klips', a term applied to the cutting off of the light of the sun from a heavenly body. An eclipse of the moon is caused by the passing of the earth between the sun and the moon. The moon is in the earth's shadow. An eclipse of the sun is caused by the passing of the moon between the sun and the earth. The earth is in the moon's shadow. The observer cannot see the sun for the moon. Since the earth is smaller than the sun its shadow comes to a point 857,000 miles away. At the point where the moon passes through the shadow its width is about two and two-thirds times the diameter of the moon. It is possible for a total eclipse of the moon to last about two hours. Even during a total eclipse the moon is not entirely obscured, but shines with a dull, copper-colored light. For a similar reason the shadow of the moon is also a cone, averaging 232,000 miles in length. At times the moon is farther than this from the earth, and it is not possible for an eclipse of the sun to take place. When conditions are most favorable, the earth enters the moon's shadow at a point where the cone is 168 miles in diameter. A total eclipse of the sun is possible, therefore, only along a belt of this width. As a matter of fact, the region within the moon's shadow is usually an oval figure having this length, but having a width not to exceed sixty or seventy miles. During a total eclipse the disc of the sun is entirely concealed within the limited region mentioned. The track of this oval shadow across the continent is called the belt or path of the eclipse. The greatest number of eclipses possible in any one year is seven. The lowest number possible is two. The usual number is four. In 1917 there will be four eclipses of the sun and three of the moon. In 1935 there will be two of the moon and five of the sun. As a total eclipse of the sun affects but a small area, any particular portion of the earth's surface is likely to be within its path only once in about 360 years. The next total solar eclipse visible in the United States will occur in 1918. Subsequent dates are 1923, 1925, 1930, 1945, 1954, 1979, and 1984. Whether partial or total, an eclipse is an interesting phenomenon. During a lunar eclipse the moon assumes a weird, spectral appearance. During a solar eclipse the blackness which comes over both the sun and the earth is truly appalling. According to a statement of a writer who was an eye witness of a solar eclipse visible in the Southern States during the early half of the nineteenth century, the blackness of the landscape was simply beyond description. Cattle roamed the pastures or stood in astonishment; chickens went to roost. Negroes prostrated themselves in terror and cried for mercy, thinking the end of the world was at hand. Astronomers seize upon a solar eclipse as a favorable opportunity to study the sun. Scientific expeditions are sent out from learned institutions to the favored region, even to remote parts of the world, when a total eclipse is due. The work of observing an eclipse is now systematized thoroughly. The most important duty during the hour is that of taking photographs for future study. See Sun ; Moon 2026 Editor's Note: This page uses language about race that was commonplace when the book was published and is offensive by today's standards. The text has been left exactly as it was printed, rather than cut or softened, so that the historical record — including how ordinary such language once was — is preserved. (Ed: BR 2026-07-22)