January 1st, 1889, several fine photographs were taken near San 

 Francisco, by Professor Toll, of the Corona, which extended from 

 10 to 12 degrees. On this occasion, reports were despatched from 

 the Observatory in the west to New York (a distance of 2,000 miles) 

 in cypher, the cypher was translated, and the translation printed 

 in less than half an hour from the time when the observations 

 were made. The value of this marvellous rapidity will be at once 

 apparent to you. An astronomer who had purposely remained in 

 New York, thus received the despatch Irom the Western Station 

 before the eclips ^ became total in Nev/ Y'ork, and was enabled to 

 verify the observations of the West, or to note any difference he 

 himself perceived in the appearance of the eclipse during totality 

 at New York. 



In the more recent solar eclipse of the 22ud of last December, it 

 was hoped that photographs might have been taken, which would 

 shew whether the corona changed during the two-and-a-half hours 

 which elapsed between the total phase at the western and eastern 

 stations. But owing to the presence of clouds over the eastern, 

 viz., the African stations, these hopes were unfortunately frustrated, 

 as no photographs could be obtained. It is, however, believed, 

 that some excellent photographs of another moot point, namely, 

 the extension of the corona and its photometric brightness were 

 obtained in the ^'alut Isles by the late Father Perry, who may, 

 indeed, be said to have sacrificed his valuable life to his devotion 

 to science. 



The application of the photometer to the measurement of the 

 light which reaches our earth from any given heavenly body, is one 

 of the most ingenious inventions of modern times. Y'"ou are all 

 doubtless aware that the illuminating power of a gas flame or an 

 eleclric light is estimated by that of a sperm candle, weighing six 

 to the pound, one such candle being the standai d unit. To test 

 this power, a photometer is used, the principal of which is simply 

 the equal illumination of the surfaces of two opposite sides of a 

 piece of paper, the candle being put on the one side, and the 

 light to be tested on the other. The weaker light is placed propor- 

 tionately nearer the paper than the stronger one, the relative dis- 

 tances thus forming an index to the difference of their illuminating 

 power. 



Mr. Dibden has applied this principle tD stellar photometry, and 

 has invented an apparatus by means of which he can, with the help 

 of an argand burner, produce an artificial star to correspond with 

 any given star in the heavens. In those cases where the approx- 

 imate distance of a star is known, you will readily perceive that the 

 intensity of its light can be fairly well estimated, bj a calculation 

 based on the relative power of the light from the real star, as com- 



