Juty 3, 1902] 
diagrams. The arrangement here called the ‘‘ Maltese 
cross,” in which the driving wheel moves the following 
wheel through a given angle once in every revolution, is 
interesting in connection with machines for counting 
revolutions. When a pair of conjugate primitive curves 
NATURE 
have been constructed, the form of the teeth is determined | 
by the condition that in order to be conjugate they must 
be roulettes traced on the primitives by the same rolling 
curve. 
From wheels rotating about parallel axes, Prof. Tessari 
passes on to bevelled cog-wheels, giving both uniform 
and variable ratios of velocities, and finally to the case 
where the shafts of the driving and following wheels are 
neither parallel nor concurrent, but are disposed in any 
positions in space. A simple application is the well- 
known modification in which the cogs on the driving 
shaft are replaced by a spiral thread. 
While the present work contains no difficult mathe- 
matical formulze, it places the theory of cog-wheels on a 
perfectly rigorous and logical basis, and the exposition 
appears remarkably simple and lucid. There are two 
lessons to be learnt from the perusal of such a book by | 
those who will learn them. The “practical man” has | 
to learn that a study of the why and wherefore of such 
matters as the shape of cog-wheels is not very difficult, 
and will help hima great deal more than merely learning | 
The mathematician, on the other | 
up empirical rules. 
hand, should see that if he will only make his knowledge 
of the geometry of conics, equiangular spirals, epicy- 
cloids and,other curves sufficiently accessible to the 
practical man he will be doing good work, and by such 
means as this he may succeed in stimulating a much 
greater demand for his abilities than exists at present. 
Here we have a subject for the proper understanding of 
which a connected knowledge of certain geometrical 
facts is indispensable. But the average mathema- 
tician is somewhat apt to discourage the learner from 
acquiring a mere connected knowledge of facts; in 
the early stages by the importance he attaches to the- 
performance of what we may call the scales and five- 
finger exercises of mathematics, and in the later stages 
by the stress he lays on the solution in the examination 
room of questions the meaning of which is often difficult 
even fora skilled mathematician to interpret when reading 
the paper at his leisure. Consequently, when the student | 
of applied mechanics wants to learn about epicycloids 
and hypocycloids for the purposes of better understand- | 
ing such a book as the present, there is great fear that he 
may not, as he certainly ought, employ the services of 
the mathematician. Gere Bs 
EVOLUTION AND DESIGN. 
The Lesson of Evolution. By Frederick Wollaston 
Hutton, F.R.S., Curator of the Museum, Christchurch, 
New Zealand. Pp. too. (London: Duckworth and 
Co., 1902.) Price 2s. 
Cy the two essays composing this little book, the first 
formed the inaugural address to the Australian 
Association for the Advancement of Science at the 
Hobart meeting in January, 1902. Part of the second 
essay formed the presidential address to the Geological 
Section of the same Association at the Sydney meeting 
NO. 1705, VOL. 66] 
219 
in 1898, while the second part of this essay, dealing with 
“Later Life on the Earth,’ has been written for the 
present work. The second essay may be at once dis- 
missed with the remark that it is a tolerably well- 
digested statement of the facts of biological evolution as 
revealed by paleontological succession. The first essay, 
which embodies the “lesson” which the author desires 
to impress upon a wider public than the audience as- 
sembled to hear the address at Hobart, is the one which 
claims the most critical attention, because the author most 
unhesitatingly and boldly declares that he has discovered 
the aim and object of evolution—that the purpose for 
which this process was designed and set going on this 
earth is “the development of man’s moral nature.” 
In order to appreciate Captain Hutton’s position, it 
may be as well to state at once that he is a thorough 
evolutionist. He begins from the very beginning of the 
process, and devotes some pages to the subject of in- 
organic evolution, in the course of which he advocates 
the meteoritic origin of the solar and other systems as 
expounded by Lockyer and supported by Prof. G. H. 
Darwin. The motive powers of evolution are gravita- 
tion (Newton), the dissipation of energy (Kelvin), and 
selection (Darwin). But granting all this and accepting 
to the full extent the teachings of modern science so far 
as concerns the mechanism of the process, there has 
hitherto been no attempt outside the theistic pulpit to in- 
troduce the doctrine of special design into the philosophy 
of evolution to the same intimate degree that is attempted 
in the present work. It is not going too far to say that 
we have here the ancient teleology, which Huxley used 
to declare had been killed by the establishment of the 
doctrine of evolution, revived and amended in terms of 
evolution. The author’s views are anthropocentric in 
the extreme. Not only is the development of man’s 
moral nature the goal towards which evolution is directed, 
but every step in the process has been regulated so as to 
lead to this end. Thus with respect to the distribution 
of the metals ;— 
“ Also if man was ever to become civilised, gold, copper 
and other metals in accessible positions were necessary, 
although they are of no use in the economy of animals 
and plants. Gold, however, would be almost useless to 
man if it was abundant, while iron would be equally use- 
less if it was as rare as gold. But we know that these, 
as well as the other substances, exist in their right pro- 
portions ” (pp. 24-25). 
“We have therefore in the composition, size and posi- 
tion of the earth overwhelming evidence of design. And 
as we can prove that carbon existed in the Archean era 
before life appeared, and that gold, iron and cepper 
existed long before man, we must also allow that the 
results of evolution had been foreseen and provided for ” 
| (p. 27). 
| coinage, copper and iron for weapons. 
If we ask further why this admirable distribution of the 
metals has been necessitated, we find in a note (p. 25) 
that it is because gold is the most suitable metal for 
It would perhaps 
be unkind to inquire further why, after the right pro- 
portions had been provided for, the subsequent distribu- 
tion of one of these metals had been left to take care of 
itself, as judged by the extraordinary disparity in the 
quantities possessed by individual members of that most 
highly civilised human community for which the original 
