266 
in also applying the same methods and principles to 
stone arches and to stiffened suspension bridges, and 
that the results so obtained are probably more to be 
depended on than corresponding results by older writers 
based on other assumptions. However, in structures of 
this class, liable to be self-strained, and with important 
factors necessarily omitted or only roughly guessed at in 
any estimate of the straining actions, we should not be 
inclined to set the same value on the results of the cal- 
culations that the author seems to attach to them. The 
remarks made on p. 519, in reference to calculations for 
a four-leg table, probably apply largely to this case, and 
indicate the more appropriate attitude of mind in regard 
to the value to be assigned to the results. 
Whilst pointing out that much of vol. i. will seem 
inadequate to an English engineer, we are glad to draw 
attention to the large number of practical examples 
scattered throughout its pages, and in many cases fully 
worked out. In fact, many students might refer to these 
with advantage, although they will have to look else- 
where for a more thorough discussion of the principles 
involved. 
The second volume consists of the author’s well-known 
treatise on “Stresses in Framed Structures,” eleven 
editions of which have already appeared, the present re- 
vised edition being the first under the new title. Some 
of the subject-matter of vol. i. is repeated in vol. ii., so 
as to make the latter complete in itself. 
Students and engineers on this side of the Atlantic 
who are interested in bridge building will wish to possess 
this volume, in which modern American practice is 
very fully dealt with. In developing the subject, the 
author gives numerous examples of the design and con- 
struction of details, worked out numerically and profusely 
illustrated by diagrams and drawings. Towards the end, 
the author quotes a standard specification for bridge 
work, in compliance with which he works out in detail a 
complete design of a typical structure, giving all the 
calculations, and accompanying the discussion by plates 
comprising a full set of working drawings. 
The volume concludes wish special chapters by experts 
on shop drawings, office work and inspection; on the 
erection of bridges ; and on lofty commercial buildings, 
in th construction of which steel enters largely. 
SURFACE-FEEDING DUCKS. 
The Natural History of the British Surface-feeding 
Ducks. By J. G. Millais, F.Z.S. Pp. xiv + 107. With 
6 Photogravures, 41 Coloured Plates, and 25 other 
..uStrations, (London: Longmans, Green and Co., 
1902.) Price 6 guineas net. 
Rr first feeling of a reader on closing Mr. Millais’s 
“ Natural [History of the Surface-feeding Ducks” 
will be surprise that one individual—though naturalist, 
sportsman and artist in one, and blessed, as the author 
has been from boyhood, with exceptional opportunities— 
should have been able single-handed to collect direct 
from Nature so much new and interesting information 
about familiar birds. 
The next will be, perhaps, a touch of regret that it 
should have been given to the public in a form and at a 
WO. 1707, VOL. 66] 
NATURE 
[JuLY 17, 1902 
price (six guineas net) which must limit its readers to 
the favoured few who have broad bookshelves and sub- 
stantial balances at their bankers, or who may be living 
within reach of rich libraries. 
But the tyranny of custom has decreed that a mono- 
graph of bird or beast, if it is to take rank as a serious 
contribution to scientific literature, must dress up to the 
part, and appear in the form and type of a family Bible ; 
and Mr. Millais, prudently no doubt, has judged it wise 
not to fly in the face of the conventionalities. 
The result is a richly illustrated and beautifully got-up 
quarto volume weighing nearly nine pounds—about as 
much as a couple and a half of well-fed mallard—de- 
scribing the life and changes of plumage of seven species 
of ducks more or less common in England, with pictures 
and shorter notices of three others which, as rare occa- 
sional visitors, have been admitted to the list of British 
birds. Mr. Millais has much that is interesting to tell 
of the courtships and varying habits of feeding of the 
ducks he writes about ; of their contrivances for escaping 
the notice of birds of prey ; and of their every-day life. 
But it is to the wonderful plumage changes during the 
period of the drake’s “eclipse,” when at a time of help- 
lessness he assumes the inconspicuous dress of his mate, 
that he has more especially devoted his attention. The 
conclusions he has arrived at add another to the marvels 
which every fresh discovery in natural history has 
revealed. 
Birds, as everyone knows, periodically renew their 
feathers, some oftener than others ; but all, or nearly all, 
probably at least once a year. As a rule—though often 
when undergoing the change they mope and show other- 
wise signs of the need of a tonic—the moult is effected 
without seriously incapacitating them. Geese and most 
kinds of ducks are an exception, and, at least in the 
case of the males, for a time commonly completely lose 
the power of flight. Why this,should be so, science has 
never yet been able to suggest. But it is, incidentally, 
where the birds most congregate, of immense advantage 
to human beings. It is during the moult that the 
Samoyedes, without much more exertion than is involved 
in driving sheep into a pen, lay in their most important 
winter stores. 
The most interesting chapters in Mr. Trevor Battye’s 
“Tcebound in Kolguev” are those in which he describes 
the great autumn goose drives in which he took part, 
when the birds, unapproachable at any other time, were 
knocked on the head by thousands to be salted down for 
future consumption. 
Nature has been a little more pitiful to the ducks than 
to the geese, and for their protection has arranged that, 
during the week or two that the duck is practically flight- 
less, he shall doff his conspicuous colouring, and mas- 
querade in the unobtrusive dress of the female. In the 
case of the mallard, the colour even of the legs and beak 
is changed, 
Nature in most of her processes works economically. 
In the matter of the drake’s ‘“‘eclipse” she is reckless. 
The strain put on the bird’s system, for no other apparent 
reason than to avoid startling contrasts and produce the 
desired results gradually, is almost incredible. 
Two-thirds of the mallard’s feathers (viz. those of the 
head, neck, breast and parts of the back and scapulars), 
