ASTEONOMY AOT) METEOROLOGY. 



TOTAL ECLIPSE OF THE SUN, AUG. 17, 1868. 



According to Dr. Edmund Weise, the shadow touches the earth 

 near Gondar, in Abyssinia, crosses the Straits of Bab-el-Mandeb, 

 including Perira, Mohka, and Aden, leaves Arabia by Cape Ras- 

 Furtak, and enters the Indian peninsula between Goa and Rajah- 

 poor. The maximum duration of totality occurs in the Gulf of 

 Siam, when it reaches on the central line no less than 6' 50'^ the 

 altitude of the sun being 87i°. On its further progress the shadow 

 runs through Borneo, Celebes, Bouru, Amboyna, Ceram, and the 

 Arrou Archipelago ; covers completely the southern part of New 

 Guinea, and then moves toward the New Hebrides, where the to- 

 tality begins at sunset. 



This eclipse is very important to astronomers from the fact 

 that the totality lasts almost as long as possible under any circum- 

 stances. At the commencement the moon will just have passed 

 a perigee of uncommon proximity, and reaches, during the eclipse, 

 the ascending node of her orbit. Thus the eclipsed sun rises 

 nearly to the zenith of those countries where the eclipse takes 

 place at noon ; and therefore the augmentation of the moon^s di- 

 ameter (due to her altitude) is a maximum, and the rate at which 

 the shadow sweeps over the surface of the earth is a minimum. 

 The result of the coincidence of all these favorable circumstances 

 will be an eclipse without rival in the records of past eclipses. 

 There are to be found only two which may be compared in size 

 with that of August 17, 1868, and none in which the totality lasts 

 so long. The first is the eclipse of Thales, May 28, 585, B. C, 

 said to have been the first predicted, and to have concluded a 

 fierce engagement between the Medes and Lydians. The second 

 was on June 17, 1435, in Scotland, and the time of its occurrence 

 was long remembered by the people of that country, as " the black 

 hour." — Proc. of Royal Astron. Soc. 



The intense brilliancy of tlie light of the sun prevents astrono- 

 mers from seeing any of the subordinate phenomena which are 

 taking place on its surface, so that little else than the spots on the 

 sun are ordinarily open to telescopic observation. Nay, the moon 

 and planets cannot be seen through a telescope when they are 

 anywhere in the neighborhood of the sun. Consequently, when 

 the dark body of the moon comes between the earth and the sun, 

 so as to totally obscure the latter, the atmosphere of the sun is 

 displayed for observation. Red prominences or flames having 

 been seen in the sun's atmosj^here during total eclipses, Mr. War- 



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