| 
JuNE 29, 1899] 
Chapter i. is entitled “Primitive Astronomy,” much 
of the space, however, being taken up by explanations of 
the various definitions of the celestial sphere. Considering 
the amount-of painstaking labour which has been de- 
voted by many modern inquirers to proving the extent of 
the astronomical knowledge of the Egyptians and other 
ancient nations, as evidenced by their temples and monu- 
ments, it is rather hard to be told that this is but ‘Sa 
plausible interpretation of these peculiarities.” 
Chapter ii., dealing with “Greek Astronomy” from 
600 B.C. to 400 A.D., is much more readable. Com- 
mencing with the introduction of the calendar and its 
various alterations, the successive celestial systems 
figured out by Plato, Aristotle, Aristarchus, Hipparchus, 
Ptolemy, &c., are very lucidly explained. The compara- | 
tively slow development of astronomy during the Middle 
Ages, from 600 A.D. to 1500 A.D., forms the subject of 
Chapter iii. Towards the end of this period, the first 
authentic conceptions of the celestial bodies being 
situated on concentric crystal spheres were enunciated. 
The fourth chapter is entirely devoted to the enormous 
impetus given to astronomical knowledge by the teach- 
ings and work of the great Copernicus, extending over 
the period 1473 A.D. to 1543 A.D. The succeeding five 
chapters deal with the life-works of Tycho Brahe (1543- 
1601), Galilei (1564-1642), Kepler (1571-1630), and 
Newton (1643-1727). 
Chapter x. deals with the progress of observational 
astronomy during the eighteenth century, the chief 
workers during this period being Flamsteed, Halley, 
Bradley, Maskelyne and Lacaille ; while the following 
chapter reviews the mathematical aspect of the science 
for the same epoch, Euler, D’Alembert, Lagrange and 
Laplace occupying the places of honour. 
Chapter xii. is devoted to the work of Herschel from 
1735 to 1822. These few chapters are extremely interest- 
ing, but it is very disappointing to find that the astro- 
nomical progress of the nineteenth century is crowded 
into the remaining fifty pages. Considering the enormous 
advances made during this period, this is wholly out of 
proportion, and in consequence many important matters 
have either been merely mentioned or omitted altogether. 
For example, although the book is sufficiently up to date 
to mention the discovery by Prof. Nasini of a terrestrial 
gas whose spectrum contained a line probably coincident 
with the chief coronal line, it is distressing to find no 
mention whatever made of the gigantic Draper Catalogue 
of Prof. Pickering dealing with the classification of stars 
according to their spectra ; indeed, the only reference to 
photographic work on stellar spectra is in connection 
with motion in the line of sight. Again, the whole matter 
of the organisation, &c., of the great photographic 
survey is contained in twelve lines. The mathematical 
portions of the science are, however, treated much more 
generously. 
The author has attempted a very difficult task in con- 
densing the whole history of astronomy into so small a 
volume, and it is from this standpoint that the book must 
be judged. Although to the individual there is much that 
is unsatisfactory, the work contains a great amount of 
useful information, which will no doubt cause it to find 
favour. 
Outlines of Physical Chemistry. By A. Reychler. Trans- 
lated by John McCrae, Ph.D. Pp. xvi + 276. (Lon- 
don and New York: Whittaker and Co., 1899.) 
THE choice and arrangement of the subject-matter of 
this book is fairly satisfactory. It includes the laws of 
chemical combination, the atomic hypothesis, the gas 
laws, vapour density, the specific heat of solids and the 
periodic system. The second part contains a fuller dis- | 
cussion of the properties of gases and the critical phe- 
nomena, the connection between chemical constitution 
NO. 1548, VOL. 60] 
197 
and the boiling point, volume, refraction and rotation of 
liquids, and the properties of solutions. The third part 
deals with thermo- and electro-chemistry and the nature 
of solutions of salts. The fourth part treats of chemical 
equilibrium and the velocity of reactions. The treat- 
ment of this subject-matter does not, however, appear 
to be distinguished by any striking originality or other 
special merit which would warrant the translation of the 
book. On p. 2, the law of constant proportions is stated 
thus: “In order to form a substance, it is always 
necessary to have the same elements united in the same 
proportions.” This is much the same as saying that 
any two samples of the same kind of matter have the 
same composition. As Mr. Hartog pointed out in these 
columns, a correct statement of the law of constant 
proportions should emphasise the view, upheld by 
Proust, that the proportions in which two substances 
combine alter fer saltum, and that there is not (as 
Berthollet believed) a series of compounds of all inter- 
mediate compositions bridging over the gaps. 
It might have been mentioned that the conclusions 
drawn by Traube from his work on the volumes of 
liquids (pp. 66-70) are not universally accepted. 
The account given of the reasons for assuming the 
existence of free ions in electrolytes is so incomplete as 
to be misleading. The work of Clausius is not mentioned, 
and the considerations which led Arrhenius to his ex- 
tension of the hypothesis of Clausius do not receive 
much better treatment. 
The evolution of heat accompanying the solution of 
| substances like hydrochloric acid or caustic soda in 
water is regarded by the author as an insuperable 
objection to the ionic hypothesis in its usual form. To 
overcome this objection he proposes a modified hypo- 
thesis in which the sodium ion in solutions of sodium 
salts, for example, is supposed to be combined with an 
hydroxyl group. In order to explain the phenomena of 
electrolysis, the charged sodium ion is supposed to be 
continually passing from one hydroxyl group to another ; 
an exactly similar supposition, however, led Clausius to 
assume that the ions spend at least some portion of their 
existence in the free state, so that the author’s modifi- 
fication appears to consist in the addition of a new (and 
unnecessary) hypothesis to the old one. A discussion 
of this kind is, in any case, somewhat out of place ina 
| book intended for beginners. 
The translation might have been better ; we do not 
like “luminary vibration” (p. 81); “the ascension of 
the mercury ” in a thermometer (p. 137) ; “‘ measurement 
instruments” (p. 189); “the comparativeness of our 
results” (p. 197); “electrolysable compounds ” instead 
of electrolytes ; “this scientist” (presumably ce savant 
in the original) ; ‘the momentary course of the reaction” 
(p. 249) instead of the velocity of the reaction at a given 
instant. 
Views on Some of the Phenomena of Nature. By James 
Walker. Part Il. Pp.vi+187. (London: Swan 
Sonnenschein and Co., Ltd.) 
AMONG the views expressed are that “Light is the 
sensation produced through the medium of the organ of 
vision by the action of multitudinous effluvia, exhaled by 
the sublimation of the incandescent substances which 
exist in the sun’s photosphere, and which are borne into 
space by an eruptive force, emanating from the con- 
tracting body of the sun.” After a review of a number of 
scientific and unscientific statements, the book concludes 
with the question “As to the ‘mode of motion’ theory 
of heat, or the ‘wave’ theory of both light and heat, of 
electricity and ether, is it any more than a fiction of the 
imagination?” Persons who would reply in the negative 
will be impressed by the arguments of Mr. James 
Walker. 
