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9 
CHAPTER V 
the decade 1860-1870. (By H. F. Newall) 
A decade which was so full of activity and achievement 
in all branches of astronomical progress as that between i860 
and 1870, makes great demands on the self-restraint of an 
astronomer who is called upon to set forth the history of our 
Society at that time. There are great temptations to the 
historian to digress from the strict lines within which he should 
confine his efforts, and to allow himself to be guided in his refer 
ences, not only to events in other decades, but also to researches 
which in truth belong to the history of Astronomy, and not to the 
history of the Society. 
This particular decade, i860 to 1870, would certainly afford a 
very interesting chapter in the history of Astronomy. But that 
is not our present task ; still, some indication must be given of the 
activity of the decade with which we have to deal. 
In it we see the application of photographical methods to 
furnishing the best basis for lunar topography and to recording 
the complex phenomena of solar eclipses. 
We see the development of spectroscopy, not only as affording 
evidence of the widespread distribution of terrestrial chemical 
elements throughout the universe, but also as giving proof of 
the radical distinction between gaseous nebulae and unresolved 
star-clusters. 
We see the bold and pertinacious attack on the measurement 
of the line-of-sight velocities of stars by means of the spectro 
scope. 
We see also another triumph of the spectroscope in the discovery 
of the nature of the solar prominences as outbursts of incandescent 
gas, and the almost simultaneous discovery of a method of daily 
observation of such prominences, which hitherto had been disclosed 
only during total eclipses of the sun. 
We see visual methods in the study of the positions and motions 
of sun-spots replaced by photographic records ; but not before the 
peculiarities of those motions and of the rotation of the sun had 
been demonstrated.