248 

impatience in tracing detail over a vast region, in the 
other a lack of that discriminating power which is 
needed in order to keep the detail in its due subordinate 
place. A nice sense of proportion and construction 
is as necessary as a sufficient technical equipment, and 
modern specialism is scarcely conducive to the com- 
bination of these qualities. 
In his preface Mr. Jones alludes to the twin diffi- 
culties of inclusion and omission. But an author need 
“not be obsessed by such problems in drawing the 
outlines of a science for the benefit of the uninstructed. 
His is the right to choose his own material. A critic 
may insist on orderly arrangement, coherence, and 
critical accuracy. He may go further and point out 
that what purports to be a complete picture falls far 
short of the intended aim, that essential features are 
lacking. But the author will do well to anticipate 
these two lines of criticism in a different spirit. The 
first is universal, and applies to all books as works of 
art or science. The second is truly pertinent, and yet 
may be disregarded by the author. For he must draw 
the picture as he himself sees it, and not as he imagines 
others will expect it to be drawn. 
or exaggerated, if that cannot be helped, but let it 
represent a personal view. In this way there is at 
least more to be gained than would otherwise be lost. 
It is only thus that a really fresh and graphic delinea- 
tion becomes possible, and that is not altogether easy 
in a field where the predecessors have been many and 
some of them distinguished. Mr. Jones has success- 
fully maintained his independence, and the result will 
be recognised as conveying a consistent, complete, 
and just representation of modern astronomy within 
the assigned limits of space and technical reasoning. 
A very simple algebraic or trigonometric formula is 
introduced occasionally, but the arguments, though 
generally effective, are elementary, and involve little 
or no formal mathematics. The book is written in a 
clear and simple style, and the illustrations have been 
chosen with judicious care. 
The last three decades have witnessed a wonderful 
transformation in astronomy. To the undiscerning 
eye the progress of the science during the nineteenth 
century may well have appeared dull. It was then 
that the foundations were being laid for future advance, 
and this on two distinct lines. Steady adherence to 
established methods was laboriously accumulating the 
material on which notable generalisations and a more 
critical view of the whole subject could be founded, 
and at the same time more enterprising spirits were 
making trial of new methods which, owing to diffi- 
culties of technique, were not always immediately 
productive. It has so happened that the triumph over 
these difficulties, with the provision of new and powerful 
NO. 2782, VOL. 111] 
NATURE 
‘be serious and not merely popular. 

Let it be incomplete. 


[FEBRUARY 24, 1923 

instrumental resources, has coincided with the critical 
discussion for which the stores of existing observations 
were ripe. The result of this confluence is that a text- 
book of general astronomy written in the nineteenth 
century, however excellent at the date of its appearance, 
could scarcely be brought up to date by any process 
short of re-writing the whole gf it more or less com- 
pletely. 
It is, however, obvious that the foundations of 
astronomy have been so well and truly laid that the 
earlier chapters must follow a long familiar track. 
The landmarks are old, but even here there is some 
liberty of choice, and Mr. Jones’s choice appears both 
fresh and judicious.. A clear preliminary chapter on 
the celestial sphere shows that the author intends to 
It is not evident 
why the definitions of the ecliptic and celestial longitude 
and latitude are deferred to a later chapter. The two 
chapters which treat of the earth are excellent, the 
topics being well chosen and discussed at such length 
as to make them really instructive. The statement 
(p. 42) that twilight is least at the equinoxes is in- 
correct; in this country shortest twilight falls some 
three weeks nearer the winter solstice. In the chapter 
on the moon, which follows, a clear statement of the 
principal features of the lunar motion is very welcome. 
The treatment of the sun naturally introduces the 
results of more modern work. It is curious that the 
word photosphere does not seem to occur, and the 
subtle problem connected therewith is entirely ignored. 
The subject of eclipses is explained very lucidly in a 
separate chapter. Here it may be noted that the index 
is capable of improvement. Thus the Einstein test by 
the deviation of stars in the field of the sun is described 
(p. 155), but omitted from the index, and the same 
thing happens with Janssen’s and Lockyer’s discovery 
(p. 130), that it was possible to observe prominences 
without an eclipse. 
As one would expect from the author, the chapter on 
astronomical instruments is excellent, dealing with the 
more important modern types in a lucid manner. 
Astronomical observations are also explained briefly 
but clearly. A very attractive account of the planets 
and their systems is preceded by a simple explanation 
of the main features of planetary motion, and followed 
by a descriptive treatment of comets and meteors. 
The concluding section of the book consists of three 
chapters dealing with the stars and the stellar system 
in the light of modern research. Possibly a fuller 
discussion of the whole of this fascinating subject 
would have been welcome, but restraint is necessary 
in a branch where research is progressing at a particu- 
larly rapid rate, and within the limits of space assigned 
it is difficult to see how a better choice of subject- 

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