246 
NATURE 
[JANUARY 14, 1897 
as exhibit a simpler structure than others, have probably 
diverged least from the primitive stock. We cannot too 
strongly insist upon the general recognition of the fact 
(self-evident though it be) that, in the present state of 
our knowledge, and in the almost total absence of palz- 
ontological evidence, our sketches of insect phylogeny, 
however useful and suggestive, cannot but be, to a large 
extent, purely tentative. 
Some recent authors have regarded the Cramébid@ as 
a totally distinct family from the Pyralzde. Sir George 
Hampson recombines them, and divides the Pyralide 
into the following twelve sub-families : Gadlertine, Cram- 
bine, Schenobiine, Anerastiine, Phycitine, Epipas- 
chiine, Chrysaugine, Endotrichine, Pyraline, Hydro- 
campine, Scopariine, and Pyraustine. 
Die Minerale des Harzes: eine auf fremden und eigenen 
Beobachtungen beruhende Zusammenstellung der von 
unserem  heitmischen Gebirge bekannt gewordenen 
Minerale und Gesteinsarten. Von Dr. Otto Luedecke. 
Pp. 643. Mit einem Atlas von 27 Tafeln und 1 Karte. 
(Berlin : Gebriider Borntraeger, 1896.) 
THIS elaborate Treatise on the Minerals of the Harz 
will be very useful, as a work of reference, to those who are 
in charge of mineral collections, and to all who are 
specially interested in those species with which the 
treatise deals. In it the author has placed on record 
the results of the observations made by him in the course 
of the last eighteen years, during which period he has 
examined the private and public collections of the region, 
and has visited the Harz localities both to satisfy himself 
on the spot as regards the existence of the minerals at 
the places mentioned, and to obtain information as to the 
modes of occurrence ; these visits were facilitated by the 
nearness of the district to Halle, of which University Dr. 
Liidecke is a distinguished professor. Further, the 
author has incorporated the results of the study of Harz 
minerals by other mineralogists. In the case of the more 
important species, such as Galena and Copper-pyrites, a 
brief sketch is given of the geological features of the 
districts in which the minerals occur. The treatise is 
accompanied by an atlas of twenty-seven plates (chiefly 
crystal figures and stereographic projections) and a very 
clear map of the region, photographically reduced from 
the one prepared by Borchers in 1865. Prof. Liidecke 
has done a considerable service to Mineralogy by the 
publication of the results of so thorough an examination 
of this important mineral region. 
The Wonderful Universe. By Agnes Giberne. Pp. 128. 
(London : Society for Promoting Christian Knowledge, 
1897.) 
To the class of readers which finds pleasure in being 
oppressed and bewildered with information as to the 
“wondrous far distances,” and especially to the members 
of it possessing a sentimental bias, Miss Giberne’s book 
will successfully appeal. Among the titles of the eleven 
chapters are “The Silver Moon,” “ Fair Venus,” “ Red 
Mars,” “Twin Giants,” and “Stars of Light.’ What 
Miss Giberne has to say on these and other subjects 
comprised in her book can usually be depended upon ; 
and, as might be inferred from the quoted titles, she aims 
at making her descriptions attractive. In the latter 
attempt, however, she is not altogether successful. <A 
sprinkling of poetical extracts, a few lapses into the 
religious aspects of astronomy, some lugubrious humour, 
and a number of statements as to how long it would take 
to go to the moon and other places in an express train, 
make up much of Miss Giberne’s latest volume. Still, 
the fact that the information can be trusted, and that it 
is very simple, is a recommendation. 
There are no illustrations, not even in the chapter on 
NO. 1420, VOL. 55] 
“How to Learn the Heavens,” and there is no index. A 
book on astronomy published with such omissions hardly 
possesses the qualifications for success. 
The Story of Forest and Stream. 
F.L.S. Pp. vi + 202. (London: 
Limited, 1897.) 
In this little book Mr. Rodway sketches, in his best 
style, the life of trees in wood and forest, and indicates 
the lessons that it teaches. He points out the benefits 
derived by man and other animals from forests and 
streams, imparting the information in pleasing language, 
and presenting nature in many instructive aspects, The 
twenty-seven illustrations are the best that have yet 
appeared in any of the volumes in the Library of Useful 
Stories, to which series the present book belongs. 
Mr. Rodway naturally devotes the largest share of 
attention to the forests of South America, for he is most 
familiar with the conditions which obtain in them. On 
this account, however, the plant-life described is some- 
what limited, though here and there comparisons are 
made between the floras of the old and new worlds. A 
more appropriate title for the book would have been 
“The Story of Tropical Forest and Stream.” 
By James Rodway, 
George Newnes 
Quelques observations sur les Muscles Peauciers du C: rane 
et de la Face dans les Races Humaines. By Théophile 
Chudzinski. Pp. go. (Paris: Masson, 1896.) 
THIS work gives an account of the arrangement of the 
superficial muscles of the head and neck in the different 
races of men. The muscles are described, and a series 
of measurements given for each in the different races. 
The general conclusion is what one would expect ; namely, 
that these muscles of the superficial fascia are most 
marked in the black races, least so in the white, while in 
the yellow races they are intermediate in their develop- 
ment. The facial muscles of the negro are found to 
closely resemble those of the gorilla in their great 
development. M. Chudzinski draws attention to the 
diagramatic manner in which the muscles of expression 
are usually figured, and notes particularly certain, very 
superficial layers which it is customary to remove in 
defining the edges of the muscles. The twenty-five 
figures, which are given at the end of the text, illustrate 
the comparative development of the muscles as seen in 
dissections of the heads of different races. 
LETTERS TO THE EDITOR. 
(The Editor does not hold himself responsible for opinions ex- 
pressed by his correspondents. Neither can he undertake 
to return, or to correspond with the writers of, rejected 
manuscripts intended for this or any other part of NATURE 
No notice is taken of anonymous communications.) 
The Meaning of the Symbols in Applied Algebra. 
Ir I had made a slip of the pen of the kind suspected by Mr. 
Cumming (p. 198), it would have been a serious error, because 
it constituted the essence of what I was writing about. I was 
sure that a number of teachers did not believe it, and Iam 
obliged to Mr. Cumming for giving me another opportunity of 
emphasising what I believe to be a vital matter. He says 
“*the multiplication of one length by another length [or, more 
generally, of one concrete quantity by another] is abhorrent to 
the mind of ” certain mathematicians. Quite true, I know it. 
The idea was abhorrent to the mind of the late Mr. Todhunter, 
and I think that Prof. Greenhill has expressed himself in the 
same sense. But what then? That is exactly why the idea 
requires driving home; and until it is driven home there will 
be no real clearness or simplicity in dealing either with physical 
quantities themselves or with their numerical specification in 
terms of given ‘‘ units.” 
