290 
NATURE 
find nothing more substantial than a number of integers 
which mutely stand and wait for elements not yet dis- 
covered, or not yet isolated in as pure a state as may be 
possible. 
I suppose we must view this table, and in fact the 
whole article, in the light of Prof. Armstrong’s dictum, 
“that imagination and even sentiment play an important 
part in chemistry, and that if too narrowly and rigidly 
interpreted, facts may become very misleading factors.” 
I do not know that this is true, but I feel convinced that 
the ruthless treatment which facts receive in this new 
table is not calculated to further exact science. 
I must pass over the doctrine of residual affinity and 
the view of chemical combination as reversed electrolysis 
which figure so largely in the article. Their application 
to facts involves a most intricate discussion. These 
views have been before the chemical world for many 
years, and I do not think the measure of acceptance 
which they have gained warrants the prominence which 
Prof. Armstrong gives them in a general article. 
Lastly, in dealing with the ionic theory Prof. Armstrong 
begins, it is only fair to say, by giving an impartial ac- 
count of it, with illustrations of its application to chemical 
phenomena. He adds to this a reiteration of his own 
objections to the theory and an exposition of possible 
alternatives which he thinks preferable. This may be 
allowable, but I cannot pass over the serious charge 
which is made, that 
“*the advocates of the dissociation hypothesis have de- 
clined even to consider the objections which may be 
raised to it from the chemist’s side.” 
I am aware of the historic fact on which this statement 
is based, but I consider it most unfair to leave the reader 
of the Encyclopzedia article under the impression that the 
ionic theory is entertained as a dogma by the large 
number of eminent chemists in whose hands it has 
been the means of effecting such remarkable advances 
of knowledge. 
I do not wish, of course, to imply that in this article 
Prof. Armstrong has done otherwise than give an honest 
account of the state of chemistry as it appears to him, 
and I affect no claim to compete with him in dictating 
the true faith. But I do say that the whole article is so 
imbued with the peculiar opinions of the author as to 
be the polemic of an individual rather than a description 
of the state of chemistry as it appears to the vast majority 
of those who follow the craft. For this reason it does 
not appear to me to be well suited for an encyclopzedia, 
ARTHUR SMITHELLS. 
SUBMARINES. 
Les Bateaux Sous-Marins et les Submersibles. Par 
R. D’Equevilley, Ingénieur Civil des Constructions 
Navales, Ancien Ingénieur aux Forges et Chautiers 
de la Méditerranée. (Paris : Gauthier-Villars, 1901.) 
\ES is curious to note the difference in the general 
appreciation of the submarine in England and in 
France. Here until recently these engines of destruc- 
tion do not appear to have been taken seriously by our 
professional guides, and, so far as the public know, but 
NO. 1708, VOL. 66] 
[JULY 24, 1902 
ittle has been done to prove their value, whereas in 
France, not only are there many already belonging to the 
Navy, but public appreciation of their utility is such 
that engineers will have to make themselves familiar 
with their history and their present lines of develop- 
ment. A handy little book such as this at three francs 
is likely, therefore, to find a ready sale. 
The first chapter relates to the history of the subject 
under the heads of the different countries. It is interest- 
ing to us to note that the earliest submarine mentioned, 
La Hollande, was constructed on the Thames in 1620 
and was worked in some way by oars, greatly to the 
delight of James I. The English have not done much 
in this line, nor have they been greatly encouraged by 
the authorities, for we are told that Johnson, early in the 
nineteenth century, navigated under the Thames in a 
submarine, which was confiscated by the Government 
on the pretext that he was going to deliver Napoleon. 
The builder of the submarine and of the motor-car seem 
to have been about equally stimulated. 
It is surprising to see how, in almost every country but 
England, the problem has been attacked by many 
inventors, France apparently taking the lead. 
The conclusion of the second chapter, that “ habit- 
ability” is the most easy thing to attain, is not what 
would be expected, nor does it seem quite to agree with 
the accounts of the exhaustion of the men that have 
appeared at times in the newspapers. 
The description of the view obtained from a sub- 
marine is interesting. At the depth of only a few metres 
it appears as if the boat is at the centre of a great 
circular hall without a roof, as refraction prevents sky- 
light from penetrating beyond the critical angle. It is 
interesting to contrast this with the appearance of the 
earth seen from a balloon. Here the observer, as the 
effect of perspective, seems to be in the centre of a vast 
concave bowl. The colour of the water is described as 
favourable for lighting by the electric arc, as the course 
can be seen for 50 metres ahead. 
Under the head of security, the author offers some 
rather chilly comfort, for he explains that as the sub- 
marine is of necessity of about the same density as the 
water, if you chance to run on a rock there is very little 
to prevent your glancing off, whereas with a surface-boat - 
the weight at once prevents its rising ina similar way. 
It must, however, be remembered that if a liner merely 
scrapes laterally against quite an insignificant iceberg 
the plating is ripped off as long as the contact lasts. Of 
course, in consequence of the higher speed and greater 
dimensions, inertia is far more formidable in this case, 
but it is difficult to believe that even’ a submarine could 
do much rock scratching with impunity. Lest, however, 
anyone should become too confident, the author points 
out that one danger always exists—that of not being 
able to go up, up, up. For this reason the system 
always employed in French submarines has much to 
recommend it. These, even when they descend, retain 
a considerable buoyancy tending to make them rise, but 
they only actually descend by the action of horizontal 
rudders or aqua planes corresponding to the aéroplane 
of a flying machine. Such an arrangement will not 
permit of remaining below the surface voluntarily when 
at rest. 
