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POPULAR SCIENCE REVIEW. 
national institution, but merely to aid the full conception of its 
mission, which, was defined in Sir John Herschel’s always happy 
words to be “ to furnish now and in all future time the best and 
most perfect data by which the laws of the lunar and planetary 
movements as developed by theory can be, compared with 
observations.” 
It will be easily seen that with all things organised to this 
end there is little room for such work as double-star measures, 
celestial photography, delineations of planets and nebulae, 
spectroscopy, &c. Some of these have occasionally been taken 
up for a time, but none of them have been, or indeed could be, 
systematically followed. 
Of late, however, there has been a tendency in some subjects 
of this character to overrun the powers of attention of 
amateurs, to whom they have been left ; and it has been 
suggested that inasmuch as they ought to be followed by the 
State, and Greenwich as at present constituted could not under- 
take the work, a special Observatory ought to be established 
and devoted to Astronomical Physics. The systematic record 
of solar phenomena (sun-spots, gaseous eruptions, &c.) has been 
mentioned as in immediate need of pursuit. Not unnaturally 
a counter question arose whether all that it was desirable for the 
State to undertake could not be done at Greenwich, and the 
Astronomer Royal laid his views upon the general question 
before the Board of Visitors at their meeting on June 1 last, in 
the following terms : — 
“ The tendency of late discoveries and consequent discussions 
in astronomy has been, not to withdraw attention from the 
exact departments of astronomy, but to add greatly to the 
public interest in those which are less severely definite. And 
this has become so strong, that I think it may well be a subject 
of consideration by the Board of Visitors whether observations 
bearing upon some of those trains of discovery should not 
be included in the ordinary system of the Royal Observatory. 
The criteria which, as appears to me, may be properly adopted 
in the selection or rejection of subjects of observation are 
these : Observations which can be made at any convenient 
times, which do not require telescopes of the largest size, and 
which do not imply constant expense, ought to be left to 
private observers. Observations which demand larger tele- 
scopes, and especially observations which must be carried on 
in continual routine and with considerable expense, can only 
be maintained at a public observatory. The claims of each 
subject must be separately considered ; but there can be no 
doubt that a very powerful demand for attention is made when 
private persons have been induced to continue observations for 
a long time at considerable current expense, and when plausible 
