April 28, 1870] 
NATURE 
651 
Des Races Humaines ou Eléments DEthnographie. Par 
J. J. D’Omalius D’Halloy. Pp. 157. 1869. (Wil- 
liams and Norgate.) 
THE author of this treatise divides mankind into 
five races, distinguished by the colour of the skin—the 
white, yellow, black, brown, and red races—which he 
holds to be more reliable than either craniological cha- 
racter or linguistic affinities ; adducing against the former, 
or Retzius’ classification, the observation of Brandt that 
in examining the crania of a large number of beavers he 
found great variations to exist ; whilst in regard to the 
classification founded on language, admitting that the 
consideration of language may prove of great service to 
ethnology, there is yet no identity between the two 
sciences. He estimates the members belonging to the 
several great religions of the world as follows: Chris- 
tianity 380,000,000, Mahommedanism 100,000,000, Bud- 
dhism 500,000,000, Brahmanism 100,000,000, other reli- 
gions 120,000,000, making a total population for the world 
of 1,200,000,000, M. D’Halloy is unusually orthodox in his 
opinions, and defends Scriptural authority with more 
energy than of late years has been customary with anthro- 
pological savants. 
Studien aus dem Institute fiir experimentelle Pathologie 
in Wien aus dem Fahre 1869. Herausgegeben von 
S. Stricker. (Wien: Braunmiller.) 
THIS is another of those German local periodical 
publications which disturb the minds and pockets of 
English readers. The time is evidently not far distant 
when a sumptuary law of publications will become a 
necessity in Germany. This, the first number of an in- 
tended series, is devoted to the histology and physiology 
of inflammation, and contains papers entitled, “ Experi- 
ments on Corneal Inflammation,” “On Cell Division in 
Inflamed Tissues,” “ On Endogenous Formation of Pus 
Corpuscles in the Conjunctiva of the Rabbit,” and others, 
in all nine in number, contributed by Stricker and his 
pupils, with a prologue “On the Present State of the 
Inflammation Controversy,” and an epilogue “On the 
Effect on that Controversy of the Preceding Memoirs,” 
both by Stricker. One paper by Oellacher, “On the 
Cleavage and Stratification of the Hen’s Egg,” has only a 
general and indirect reference to inflammation, 
Sketches of Life and Sport in South-Eastern Africa. By 
Charles Hamilton, F.A.S.L. (London; Chapman 
and Hall. 1870.) 
WE do not understand with what object this book has 
been published. Of sketches of sport there are few, and 
none that can compare in interest with the many exciting 
records of South African adventure in earlier books with 
which we are familiar. The author’s ideas on all subjects 
eonnected with natural history are of the vaguest, as 
where he says, “ The Struthionidae may comprise, for 
what I know, other species besides those of the ostrich ; 
a geologist would give the reader information on the 
possibility of these birds existing in some analogous form 
centuries before the present formation of the globe!” Of 
sketches of life there are some, but with not much greater 
claim to novelty. That Mr. Hamilton succeeded in so 
far divesting himself of European prejudices as to submit 
to be carried to his bath by twenty buxom Kaffir girls, 
and after having been ducked by them in the water (an 
operation which he found “rather agreeable than other- 
wise”), to be painted over with red earth, may be interest- 
ing to himself and his friends, but hardly to the general 
public. What becomes of the old crinolines appears from 
the fact that the ordinary costume of a Kaffir school- 
girl is a necklace and an outrageously large skeleton 
crinoline without any covering over it. The wood- 
cuts are on a par with the letter-press, and would be a 
hideous disfigurement to any work of higher literary 
pretensions, 
LETTERS TO THE EDITOR 
[The Editor does not hold himself responsible for opinions expressed 
by his Correspondents, No notice is taken of anonymous 
communications. | 
Analogy of Colour and Music* 
I HAVE read with interest the letters in NATURE of gist 
March, on the relation between the harmonies of sound and 
colour, and I wish to point out that the most important principle 
of harmonising in colour is one which has no parallel or 
analogue in sound, except only that, like the harmony of 
sound, it has a mathematical basis. I mean the law that 
complementary colours harmonise with each other. The 
definition of complementary colours is, that any two colours which 
are complementary and of equal intensity, produce white when 
combined. In sound, on the contrary, there is nothing analogous 
to white, and consequently no relation analogous to that of 
complementaries. 
All possible colours except white are colours of the spectrum. 
Black is only the negation of light, and grey is a subdued or 
lowered white. Brown tints, which to the eye appear unlike any 
of the colours of the spectrum, are ‘‘merely red, orange, or 
yellow, of feeble intensity, more or less diluted with white.” 
(Clerk Maxwell, P2losophical Transactions, 1860.) ‘‘ One 
circumstance, however, must not be left unnoticed here : 
namely, the difficulty of obtaining [that homogeneous red 
light which forms the transition between the violet and red of the 
ordinary spectrum, and which can only be produced by the 
prism under remarkably favourable circumstances (on a bright 
summer's noon), This outermost colour of the spectrum, which 
may be equally well regarded as extreme red or extreme violet, 
I will call purple . . . . In point of fact, the transition 
from violet to red is just as continuous to the eye as that 
between any two other colours, though the limit has not yet been 
fixed by observation at which the same impression of colour is 
produced by a different duration of vibration.” (Prof. 
Grassmann, Philosophical Magazine, April 1864.) 
The duration of vibration at the extreme of the violet end ot 
the visible spectrum is about twice what it is at the extreme of 
the red end. According to. Sir John Herschel (Good Words, 
August 1865), the vibrations at the extreme ends of the 
spectrum, number respectively _399,401,000,000,000 and 
831,479,000,000,000 to the second; so that those of the 
extreme violet are a little more than twice as numerous as those 
of the extreme red, and the power of vision extends through a 
little more than a large octave. 
With these facts before us it is scarcely possible to doubt that the 
principle of the octave is as true of light asof sound. Any two 
notes, whereof the vibrations producing the one are exactly twice 
as numerous in the same time as those producing the other, are 
in a manner recognised as the same note, the one being the octave 
of the other. It isin the highest degree probable that the same 
is true of light, and that ‘‘ the limit at which the same impres- 
sion of colour is produced by a different duration of vibration”’ 
is at the point where the vibrations of the one are exactly twice 
as numerous in the same time as those of the other. 
Independently of this speculation (which isnot a new one), it 
is a fact of observation, and is indeed only a statement in other 
words of the fact quoted above from Prof. Grassmann, that the 
order of the tints in the spectrum is recurrent. According to 
Prof. Grassmann, the order of the tints is the following :— 
1. Red, 7. Azure. 
2, Orange. 8. Indigo. 
3. Yellow. g. Violet. 
4. Yellowish green, 10. Purple. 
5. Green. Red again, 
6, Bluish green. 
And he maintains, reviving Newton’s theory, that every colour 
has its complementary in the spectrum ;—the series of comple- 
mentaries being this :— 
1. Red + bluish green = white. 
2. Orange + Azure = white. 
3. Yellow + indigo = white. 
4. Yellowish green + violet = 
5. Green + purple = white. 
white. 
*The importance of the accompanying letter from Mr. Murphy induces us 
to reopen a subject which we had considered closed ; we append also two 
others previously received.—Ep, 
