ASTRONOMICAL PROGRESS IN 1902. 



stellation Octans. Allen B. Cobham received 

 statistics from 25 stations. Mathematical com- 

 putation revealed the fact that along its visible 

 path its average height was about 50 miles, 

 and its velocity 33 miles a second. A few min- 

 utes after it disappeared a loud report like dis- 

 tant thunder was heard at all the stations which 

 shook buildings. At some places a double report 

 was heard. 



Meteoric Stones.^-That bodies when they 

 fall to the Earth, which they sometimes do, are 

 identical with meteoric stones is conceded. They 

 are of all sizes and shapes from that of a marble 

 to 100 tons. Recently Prof. Henry A. Ward, 

 of Chicago, who is an authority on the subject, 

 visited Mexico to inspect, a stone that was 

 reputed to have fallen from the sky. He found 



THE OKEAT METEORITE IN MEXICO. 



it to be a very remarkable one. (See illustra- 

 tion.) They never fall perpendicularly, and 

 when they are large they plow a long, deep chan- 

 nel. He hoped to be able to remove it to Chi- 

 cago, but found it to be impossible. He esti- 

 mated it to weigh 50 tons. As it is far from a 

 railroad or shipping port, it will probably never 

 bo moved. It is partly hidden in a long deep 

 channel that it dug. 



Meteorites are of two kinds iron and stone. 

 If a stone is seen covered with a rough, jet-black 

 crust, with many depressions of all sizes and 

 depths, it is a meteorite. The hollows are 

 gouged out in passing through the air, producing 

 tha sparks that are seen during its visibility. 



Star Showers. On the mornings of Nov. 12, 

 1799, Nov. 13, 1833, and Nov. 14, 1866, the world 

 was treated to magnificent star showers. The 

 intervals between them (thirty-three years and 

 one day) furnished a strong suspicion that they 

 would again recur on Nov. 15, 1899, but at that 

 date no meteors appeared, or no more than are 

 usually seen about Nov. 14. This shower can be 

 traced back nearly one thousand years. The 

 sun appears to be surrounded with a meteoric 

 ring of what are called, before consumed in our 

 atmosphere, meteoroids, and while visible, un- 

 dergoing combustion, meteors and shooting 

 stars. The earth in its annual path around the 

 Sun passes through the ring every year about 

 Nov. 14, and produces a slight display. The 

 ring, supposed to be composed of the ejected 

 tails of millions of comets, appears to be un- 

 equally dense, one place in it being exceedingly 

 dense, through which the Earth passed in 1799, 

 1833, and 1866, but not as was expected in 1899. 



The ring completes a revolution round the Sun 

 in about thirty-three years and a quarter, thus 

 causing the Earth to pass through it every year 

 in a new place, and once in about thirty-three 

 years through the dense place. The shower in 

 1833 surpassed all its predecessors. 



Prof. W. H. Pickering says that the obser- 

 vation of the Leonids, as the shower is called, 

 appears to indicate that the 33.25 year period 

 must be abandoned, on the ground that since 

 1698 the length of the period has been thirty- 

 four years. Remembering that brilliant displays 

 were seen in 902, 1002, 1202, and 1602, it seems 

 possible that it will yet return in November, 

 1902, but unfortunately there will be a full moon. 

 If it does appear it will be just one thousand 

 years since it was first recorded in history. 



Another notable shower of meteors occurs 

 every year on Aug. 10 whose elements agree with 

 those of Swift's comet of 1862, having a period 

 of one hundred and twenty-three years. A fine 

 display was seen in Europe on Aug. 10, 1902. 

 They are called Perseids, because they appear to 

 radiate from the constellation Perseus. 



Distances of the Stars. The grandest and 

 most difficult problem man ever attempted to 

 solve is to ascertain the distance of a few of the 

 brighter stars. The problem has not yet been 

 solved with the desired accuracy. One element of 

 doubt is the Sun's distance from the Earth, which 

 has engaged the attention of astronomers for at 

 least three thousand years. The process resorted 

 to is briefly as follows: The velocity of light is 

 assumed to be 186,325 miles a second, as a year 

 contains 31,556,926 seconds, the product of these 

 two numbers will give the number of miles cor- 

 responding to a " light year." A star having a 

 parallax of 1" is distant 3.26 light years. The 

 parallaxes of the stars, however, are, with per- 

 haps a single exception, much less, and the less 

 this is the greater its distance. If the light 

 year of a star having a parallax of 1" be divided 

 by the assumed parallax of any other star the 

 result gives the distance in light years. Suppose 



the parallax of the star to be 0.5", then ^ 5 = 

 6.05 years that is, the light has been more than 

 six years in reaching us, moving at a velocity 

 equal to seven times round the Earth in one sec- 

 ond. The nearest known star is Alpha Centauri, 

 whose parallax is not quite 1". It is distant 

 about 3 light years. All this, however, depends 

 on the correctness of the computation of the par- 

 allax, an assumption seldom if ever trust- 

 worthy. The following list comprises the best 

 determination : 



Proper Motion. In common parlance the 

 stars are called fixed stars; but, strictly speak- 

 ing, there is not a fixed star in the universe. 

 Every one is attracted and swayed by the others 

 and in all directions. Their apparent motion, 

 though very rapid in miles, is. from their groat 

 distance, exceedingly slow. The proper motions 

 of several thousand have been determined with 

 great exactness, both in right ascension and dec- 

 lination, and catalogued. Proper motion is not 

 applied to motion of stars in the line of sight, as 

 they appear absolutely stationary. 



