4 
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 from the Western Station 
before the eclips2 became total in New York, 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 22nd 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 falut 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. You are all 
doubtless aware that the illuminating power of a gas flame or an 
eleciric light is estimated by that of a sperm candle, weighing six 
to the pound, one such candle being the standa: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 to 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, by a calculation 
based on the relative power of the light from the real star, as com- 
ee 
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