316 The Construction of the Heavens. (July, 
discern only a few stars even with the assistance of the best 
telescopes, are probably systems which are still more 
distant than the rest.”” On the other hand, he inferred that 
those stars ‘‘which being placed at a greater distance 
from each other compose the larger constellations, and such 
as have few or no smaller stars near them when examined 
with telescopes, belong probably to our own system. - 
Variable stars he also regarded as in all probability members 
of the system of stars to which our sun belongs; though 
the reasoning on which he based this opinion is not such as 
can now be admitted; for he considered their variations of 
brilliancy to be due to variations of distance (a cause which 
would necessarily be more effective in the case of stars 
relatively near to us); but we now know that this explana- 
tion is not the true one. He also judged red stars to 
be much larger and nearer than their apparent brightness 
would suggest, and hence inferred that they also belong 
to the system of stars which includes our sun. 
In passing to the work of Sir W. Herschel as a student 
of the sidereal heavens, I cannot but express some degree of 
surprise that so little has been done to bring the records of 
his labours properly before the student of astronomy. His 
papers merely collected into a volume would form a most 
important accession to astronomical literature. But if 
suitably edited and illustrated by the work of his son, and of 
others who have succeeded in the same field of research, 
the volume would do more to advance the study of sidereal 
astronomy than any work which has been published during 
the last century. It must be added that nearly all that has 
hitherto been done in making Herschel’s words and work 
public, has been rather an injustice to his memory than 
otherwise. It seems to have been supposed that his 
own account of his work might be treated as we should 
treat such a work as Sir John Herschel’s “Outlines of 
Astronomy,” and that extra¢ts might be made from any 
part of any paper, without reference to the position which 
that paper chanced to occupy in the complete series. It 
does not seem to have been noticed that not only was there 
a progression in the ideas as well as in the work of the 
great astronomer, but that there was a complete change in 
his opinions during the progress of his labours. Hence 
views expressed by him in his earlier papers are not uncom- 
monly in strong contrast with those which he advocated in 
later years; opinions which he regarded as certainly just at 
one time were rejected as most probably incorrect after 
a few years of fresh labour; and whereas in 1785 he enun- 
