( 8io ) 
[December, 
NOTICES OF BOOKS. 
A Handbook of Double Stars, with a Catalogue of twelve hundred 
Double Stars and extensive Lists of Measures. With Addi- 
tional Notes, bringing the Measures up to 1879. For the 
use of Amateurs. By Edward Crossley, F.R.A.S., Joseph 
Gledhill, F.R.A.S., and James M. Wilson, M.A., F.R.A.S. 
London : Macmillan and Co. 1879. 
It is said that one-fourth of the stars are multiple stars, and yet 
their study dates only from the time when the telescope was first 
used in astronomical research. Thousands of observations have 
since been made, and much has been written on the subject. 
There is, however, no convenient handbook for the guidance of 
students of sidereal astronomy. The present work is written in 
order that future students may know what stars are of especial 
interest, at what time observations are especially needful, and 
what stars have been so frequently and satisfactorily measured 
that for the present day they need no attention. 
The book is divided into four parts. The first part is historical, 
and descriptive of instruments and methods ; the second is ma- 
thematical ; the third contains lists of measures of the most 
interesting double and multiple stars, with historical notes on 
those which are of special interest ; the fourth part is biblio- 
graphical. 
Part I., Chapter II., contains an excellent description of the 
Equatorial ; the Clock, its construction and adjustments ; the 
Observing Chair ; and of the best form of Observatory. Chap- 
ter III. gives an account of the Equatorials which have been 
used by double-star observers. Chapter IV. is on the Micro- 
meter ; and Chapter V. describes the methods of observing, &c. 
The first and second chapters of the second part give a detailed 
account, with a fully worked example, of determining an orbit 
and an ephemeris by a purely graphical construction founded on 
Herschel’s and Thiele’s methods. An example of the application 
of analysis to a double-star orbit already approximately known by 
graphical methods is given in Chapter IV. Chapter V. is on the 
effects of proper motion and parallaCtic motion ; and Chapter VI. 
is on the mode of combining observations and determining their 
weight. 
Part III. contains a catalogue of double stars selected as of 
special interest, with a list of all accessible measures. 
The work is illustrated, and is written in such a simple style 
that the most uninitiated student will have little difficulty in mas- 
tering the subjeCt, while it will prove a most valuable work of 
reference to the experienced astronomer. 
