Arizona republican., 1898-01-22
THE SOLAR ECLIPSE TODAY.
What the Astronomers Hope to Learn
 From It.

se FrOm IL.
 Today, when/ it is about noon in Bombay, and about getting up time in Phoenix, there will be a total eclipse ofsthe sun, visible chiefly in western India. The circular shadow of the moon, cast by the sun upon the earth, and about eighty miles in diameter, will come sweeping across the Ara- bian sea from Africa, will enter Hin dostan about two hundred miles south of Bombay, and will pass norshs ast- erly up toward the Himalayas and Thibet. Along the center of the pa h travelled by this swiftly moving shad- ow the sun will be completely hidden for two minutes. More than forty miles away, on either side of the track the eclipse will be partial, not total.
 Astronomers hope to learn much from their observations during the exceedingly brief period of totality; and, while so great a number of sc1- entists have not gone to witness this show as went to Norway and Japan in 1896, or to South Africa and Brazil z in 1893, there will, nevertheless, be a notable assemblage along the first two hundred or three hundred miles of the path of the eclipse in western India. That American veteran on eclipse work, Professor Todd of Am hert, has not attended this exhibition, but the Lick observatory will be rep resented by Professor Campbell, and a less famous observatory in Oakland, Cal, sends Charles BuaIckha,ter, who has an invention for equaliZing the light of the outer and inner paris of the corona, so that better photographs of the solar appendage may be ss- cured M Deslandres, a well known French spectroscopist, who has in the past sought to determine whether the corona revolves at the same rae as the sun, will also be absent on this occasion.
 Great Britain, however, will be well represented. Sir Norman Lockyer, a high authority in solar physics and spectroscopy, will be accompanid by his son, w. J. s. Lockyer, and A. Fow- lef, one of his assistants at the South Kensington observatory. They will be stationed at Vizia burg, on the coast. Cooperating with Sir Norman will be two or three other parties, stationed few miles away. Another expedition, led by the astronomer royal of England, MT. Oh .istie, and including MT. Turner (also of the GreenNch observatory and Dr. A. A. C0mmd4, who has private observa- tory N Ealing, will occupy other postsf A third British party will in- -So1 MT. Newall of Cambridge; Cap tain Hills of the Royal engineers, and Dr. Copeland, astronomer royal of z<<fIt t tY1h7.f N
 Royal astronomical society, mos 1y amateurs, have secured suitable pla es For convenient observation, more for their own entertainment, However, than with the hope of making impo : tant discoveries. Two or three East Indian astron omers will aIso engage in the work of watching and photo graphing the sun on this occasion.
 The problems on which s:ten ion has of late been cor acentrated almost exclusively, at times of total eclipses Of the sun, relate to the composition and arrangement of the various lay CTS of vapor and dust which enyeIop that body as with an atmosphere Photography and pencil sketching will be employed to some extent to secure record of the corona's out line and strea kiness, for compar.s son both with earlier pictures of the same sort and with another class of DOT traits of the corona that will probably be secured this year. But the great majority of the observational and photographic work done today will be spectroscopic. Either there will be huge prism outside and in front of the object glass of a telescope, or else there will be a spectroscope at- tached to the eye end of the instru- ment.t
 The former combination of appar- atus known as the "prismatic cam era, has long been used by astrono- mers for photographing the spectra of stars. Excellent work of this class has been done, for instance, by the Harvard astronomers, at their Pe- ruvian station. The application of the pr1smatic camera to solar research IS mora recent. It is hardly neces- sary to remind readers that the char acteristic spectrum of an incandssc nt substance consists of series of bright lines, parallel with each other. ar ranged like tiny cross bars on a practically invisible ribbon. These lines are luminous images of the slit through which the light under exami nation enters the spectroscope. If instead of slit, a ringlike aperture were employed, the lines would be circular, and very likely some of them would overlap each other.
 Now, just at the instant when the black moon completely hides the pho- toshpere tor luminous cloud of the sun), ring of less vivid light, which had been previously invisible, sudden ly leaps into view. And suitable prism, cut in front of the object glass of a telescope or camera, will give a spectral Image, down at the eye end, made up of a series of rings