FEBRUARY 8, 1901.] 
This sumptuous volume of 165 folio pages 
worthily represents a part of the work which 
has been quietly in progress during the past 
forty years at the little private observatory at 
Upper Tulse Hill, London, one of the most im- 
portant outposts at the frontier of astrophysical 
science. The additional title, ‘ Publications of 
Sir William Huggins’s Observatory, Vol. I.,’ - 
leads us to hope that this introductory volume 
may soon be followed by others which shall give 
in similar manner the results which have been 
gained from the minute study of the large store 
of photographs which have been secured by 
the talented authors during many years of 
patient experiment and observation. 
The first chapter gives a brief ‘ history of the 
observatory, and of the work done therein.’ 
At the present day, when a photograph of the 
spectrum of a bright star may be obtained with 
an exposure of but a few minutes,—or even 
seconds, we are likely to fail to appreciate the 
difficulties and discouragements of the pioneers 
in these delicate researches, and we may forget 
how our present large and rigid instruments 
have slowly evolved from the first combinations 
of spectroscopes and telescopes. It was soon 
after the establishment of the private observa- 
tory that Mr. Huggins learned of the discovery 
by Kirchhoff and Bunsen of the true nature of 
the dark lines of the solar spectrum, which had 
been unexplained for more than half a century 
after their discovery. It at once suggested a 
wide field of research, and, as the author states, 
“then it was that an astronomical observatory 
began, for the first time, to take on the ap- 
pearance of a physical laboratory.’ With the 
collaboration of Professor W. A. Miller, the 
spectra of forty stars and of Jupiter and Mars 
had been observed at the end of 1862. The 
news of the similar work of Mr. W. M. Ruth- 
erfurd in America arrived on the day the pre- 
liminary paper was to be read at the Royal 
Society. 
The photography of stellar spectra was at- 
tempted in 1863, the wet process, of course, be- 
ing employed, but the dark lines were not 
shown on the plates until the attempt was re- 
sumed in 1875. Meanwhile the chemical origin 
of a number of the lines in stellar spectra was 
established, and in 1864 Mr. Huggins made his 
SCIENCE. 993 
famous observation on the spectrum of a nebula, 
demonstrating its gaseous constitution. In 
1866 a temporary star, Nova Corone, was first 
observed spectroscopically; and in the same 
year was begun the construction of a spectro- 
scope for determining the velocity of stars in 
the line of sight, the results of the use of which 
were published in the Philosophical Transactions 
in 1868. Later, attention was given to the spec- 
tra of comets, and to attempts at the spec- 
troscopic observation of the red prominences 
previously only seen during solar eclipses. Al- 
though the principle underlying their visibility 
in the spectroscope was clearly stated by Mr. 
Huggins early in 1868, he did not actually 
succeed in detecting them until after their dis- 
covery by Lockyer and Janssen later in that 
year. 
Larger instruments and the dry-plate process 
permitted much progress in the work on stellar 
spectra after 1875, which is recorded in numer- 
ous papers read before the Royal Society in the 
subsequent years. The titles of eighty-two 
papers on work done at the observatory are 
given in the second chapter of the work. Chap- 
ters III. to V. describe the instruments and 
methods of obtaining the spectra, and of broad- 
ening them, the descriptions being largely 
quoted from the journals in which they were 
originally printed. 
Chapter VI. occupies one quarter of the 
volume, and is entitled ‘ Discussion of the Evo- 
lutional Order of the Starsand the Interpreta- 
tion of their Spectra,’ with sections on (1) the 
types of stellar spectra, (2) original differences 
of stellar constitution, (3) classification of stellar 
spectra, and (4) physical and chemical interpre- 
tation of stellar spectra by means of terrestrial 
spectra observed in the laboratory. 
In addition to its ahsorbing interest to stu- 
dents of astronomy, this chapter can hardly 
fail to be attractive to the general reader of 
scientific topics. The author quotes freely 
from his published addresses bearing upon this 
subject, and brings into discussion the work of 
other astronomers and physicists, although 
drawing his observational data chiefly from his 
own work. In the matter of classification of 
stellar spectra the author follows in the main 
the scheme suggested by H. C. Vogel in 1874. 
