APRIL 19, 1901.] 
of the sun and planets. Chapter II. gives a 
general description of the constellations and a 
discussion of the various star catalogues and 
charts since the time of Hipparchus. The next 
two chapters deal with stellar magnitudes, re- 
ferring particularly to determinations of bright- 
ness made without instrumental means. The 
number and distribution of the stars, and a 
study of the Milky Way occupy two chapters. 
The proper motion of the sun and the vari- 
ous methods of determining the apex of the 
sun’s way are next considered, and this is 
naturally followed by the proper motions of 
the stars. An especially interesting table is 
that giving a comparison of the radial velocities 
with the proper motions on a great circle for 
fifty of the brightest stars. Chapter IX. treats 
of stellar parallaxes, giving the results ob- 
tained by many investigators. The volume 
closes with a chapter of 50 pages on variable 
stars. 
The orbits of binary systems and the various 
methods of their calculation (Herschel, Kowal- 
sky and Glasenapp, Zwiers) are discussed at 
considerable length, together with their number 
and dimensions, in the opening chapters of the 
second volume. A table is given containing 
the elements of sixty-six known orbits. The 
effect of the introduction of a linear element, 
the radial velocity, is treated in one of the sec- 
tions, and M. André has calculated for the 
sixty-six well-established binaries the epochs at 
which a maximum radial velocity may be ex- 
pected, and the value of that maximum on the 
assumption of a stellar parallax of 0/7.2. ‘ As- 
tronomy of the Invisible’ is the title of a 
chapter of 37 pages, dealing chiefly with the 
orbits of Sirius, Procyon, 6 Cancri, and 70 
Ophiuchi. 
The methods of Rambaut and Lehmann- 
Filhés for computing the orbits of spectroscopic 
binaries are given in sufficient detail in a sepa- 
rate chapter. About one hundred and thirty 
pages are next devoted to ‘photometric bi- 
naries.’ This includes a full historical account 
of Algol and its investigation by Pickering, 
Harting, Vogel, Chandler and Tisserand, to- 
gether with all available data as to seventeen 
other variables. of the Algol type. Dunér’s 
beautiful work on the orbit of Y Cygni, pub- 
SCIENCE. 
619 
lished last spring in the Astrophysical Journal, 
was unfortunately too late to be included. 
Subsequent chapters treat of the clusters and 
nebule, in particular of the Pleiades, Pre- 
sepe, and the region of 7 Carine; of the dis- 
tribution of these objects, and of their distance. 
Globular clusters have a chapter of their own, 
which includes Bailey’s recent remarkable vari- 
ables. A short chapter is also given to colored 
stars. 
The two volumes contain over one hundred 
cuts, and three excellent plates, and are printed 
in the usual excellent manner of Gauthier- 
Villars. A rather large list of errata is given, 
and probably more will be found. The book 
abounds in examples of the characteristic 
French disregard of the correct spelling and 
initials of foreign proper names. 
This somewhat detailed account of the scope 
and contents of the work has been given to 
justify the remark that it fills a gap in the lit- 
erature of thesubject. The book would seem to 
be very well adapted for a basis of an elective 
course for seniors in our colleges, and the sub- 
jects treated are surely of greater freshness and 
interest, and of no less value in mental dis- 
cipline, than the customary courses on the orbits 
of comets and planets. 
A third volume is promised to complete the 
work—on the methods and instruments of 
modern research, and on the formation and evo- 
lution of the universe. 
EDWIN B. FRost. 
The Steam-engine Problem. By S. H. BARRA- 
CLEUGH, B.E. (Sydney), M.M.E. (Cornell). 
Russell School of Engineering, University 
of Sydney, N. S. W. Sydney, Kealy and 
Phillip. 8vo. 1900. Pp. 47. Figs. 13. 
In this little book of less than fifty pages, 
Professor Barracleugh admirably outlines the 
problem of the steam-engine as it is now com- 
ing to be enunciated by scientific engineers and 
by thermodynamists who recognize the fact that 
the thermodynamics of the ideal may not con- 
stitute all, and that the real engine offers a com- 
plex problem which involves the most abstruse 
studies in physics, mechanics and energetics. 
This outline originally appeared in substance 
in the Australian Technical Journal. It was 
