The Birmingham age-herald., 1903-08-09

photograph a comet as it's motion through space carries it rapidly across the heavens It is, of course. necessary to follow the comet with the guiding telescopes the stars in the vicinity are, therefore drawn out into trails.
 Those on the plate of July 2S had an extent of 7-100 of an inch. which gives an apparent motion of about 200 seconds of arc per hour for the comet On pho tion was shown to be just twice as great, but the tail was only two degrees long.
 This is a print of one of my negatives. l exposed the plate an hour and a half" The print shows a blot of white in gray field, which is dotted with narrow white sits about a tenth of an inch long. Some are fainter than others, but all point in the same direction. These slits are photographs of stars and they are given their peculiar appearance by their motion and the long exposure of the plate. Prof Peters is one of the best astronomical photographers in the country. He Is in love with his profess sion and has followed it ever since he was very young.
 Seen Through the Glass.
 "The comet through a telescope" said Captain Chester, in answer to a question, 'has the appearance of a small planeta- ry nucleus. surrounded by a nebulous en- velope Its tail extends away from the sun and is about two degrees long. Just now the tail looks shorter than it actu- ally is because 1t is presented obliquey to our view.
 Tn special telescope called a comet seeker which Is used to discover com cts, the tail can be followed for a some what greater distance perhaps l would say two and one-half degrees; say five times the diameter of the moon. The Borelly comet is the brightest seen here in recent years. It is, in fact, a star of about two and one-half magnitudes at its brightest. For the reason that it is so bright Washington folks have viewed 1t on clear nights through opera and field glasses
 "This diagram will give you a good idea of the comets course," said Cap tain Chester taking up two pieces of cardboard joined and cut in the shape of parabola and an Ellipse. The blunt nose of the paraboIa representing the course of the comet, intersected the eclipse, which represented the orbit of the earth.
 'The comet has been receding from us and approaching the sun ever since July 27, the day when it was nearest the earth. Its least distance from the sun on perihlion passage will be on August 27. On account of the position of its orbit with respect to the path of the earth. or the elliptic, as 1t is called, the comet will again approach the earth after it's perihilion, but at that time 1t will be vis- ible in the southern heavens only.
 Other WeI-known Comets.
 Many of the comets that appear re- main visible but a short time while they fr, fI,aa ,ofs of t.fJ, Computation shows that in many in stances they are visitors to the solar system from outer space In this case the orbit is either parabolie or hyper parabolic, and so the comets can never return The comet now visible, which we call Comet c. 1903, probably belongs to this class. By the attraction of some of the larger planets they are some times turned from their course enough to enable the sun to retain his grasp upon them and then they assume place in the solar system. Such comets are known as periodic.
 There have been but few bright com cts visible in recent years. The great comet of 1882 which appeared in Sep tember of that year, is still remembered by many people. It was so bright as to be visible even in the day time, and while close to the sun. For many months SPAtohiSdCto ject in the early morning sky. Another bright comet was discovered in May, 1901 but was visible to observers in southern attitudes only. It was first seen in Australia, but Prof. Dinwiddie here discovered 1t independently at so- lok Sumatra, a few months afterwG d. Prof. Barnard photographed it. Both these gentlemen were members of the naval observatory eclipse expedition To- oated there.
 "The degree of brilliancy a comet may assume on approaching the sun can only be predicted theoretically. Some of these bodies have been known to in- crease more rapidly in brightness near perihlion than theory would indicate. Consequently, this present comet of Bor- ely may become much brighter"
 A Shower of Meteors.
 "If this comet met the earth' said Prof. Peters. "T believe the result would be a shower of meteors, a marvelously beautiful spectacle attended by the igni- tion of the meteoric particles composing the body of the comet.
 Many people are not aware what a perfect shield the transparent air around the earth is. If you run hard against the wind you feel the resistance When this forward motion is reckoned in miles in- tead of feet per second-it is said that the comet travels at the rate of 100 miles in a second-you get some appreciation of what the resistance, the friction. and consequently what the heat engendered, would be.
 "A comet entering this cushion, this armor of air, would have its particles heated instantly to a very great degree, they would be disspated in dust and vapor. possibly before they reached the earth. But there is no danger of the comets striking the earth"
 "None,' said Captain Chester. "Not at | al coi1 prof Dfpurid6ia