292 
NATURE 
sea works has no convenient formule to guide him, 
but only previous experience and precedent. This is 
evident from the volume before us, for most of 
the sea works described are improvements on previous 
constructions. 
The author commences with a description of the 
natural laws which govern the general movements of the 
sea, the causes and action of its waves, tides, currents, and 
consequent changes in the coast line, the knowledge of 
which is all important when any new works are pro- 
jected ; indeed, it is not too much to say that many sea- 
works have proved very expensive in their maintenance 
owing to ignorance of the above conditions when they 
were cesigned. 
The author divides the various types of harbours into 
five classes—(1) estuary harbours; (2) harbours with 
back-water ; (3) harbours partly sheltered by nature ; (4) 
harbours protected solely by break-waters ; (5) peculiar 
types of harbours with detached break-waters. After 
having given long and clear descriptions, with excellent 
illustrations of the several types, the author remarks with 
reference to the first three classes and their shelter from 
the sea :—‘‘ Some natural shelter exists in all the harbours 
referred to above, but it will be noticed that the amount 
of shelter varies considerably. Thus whilst at Cherbourg, 
Plymouth, Wick, Genoa, and Barcelona the entrance 
alone of a complete bay requires protection ; at Holyhead, 
Table Bay, and Alexandria only a portion of the extensive 
bays in which the harbours are situated can be utilised, 
though the existence of the bay diminishes considerably 
the exposure; and lastly, at Dover, Newhaven, and 
Colombo projecting points of the coast, rather than 
regular bays, are taken advantage of for the site of a 
harbour.” After discussing the last two classes of 
harbours, we have the conditions which govern the size 
and position of the entrances to harbours explained. We 
commend these chapters to the careful perusal of those 
who take an interest in the proposed harbours of refuge, 
for here will be found considerable information concerning 
the advantages of the several sites proposed. 
Chapter V., and those following, until the end of Part I. 
of the book is reached, deal with perhaps the most im- 
portant of all sea-works—viz. break-waters. The author 
classifies their several modes of construction into three 
classes—(1) mound of rubble and concrete blocks ; (2) 
mound with superstructure ; (3) upright wall. Under 
these heads we find all the principal break-waters, each 
being well described, the construction explained, and 
reason given for any special work. 
It is interesting to follow the gradual increased use of 
Portland cement concrete in the place of natural stone, 
and, as the latest break-water, we may take the one at 
Newhaven now in construction. This break-water is 
practically one solid mass of cement concrete. It is built 
on the upright wall system, with concrete in bags de- 
posited from hopper barges on the chalk bottom up to 
low-water, and concrete-in-mass above. The bags each 
contain about 104 tons of concrete, the concrete being 
mixed by a special machine consisting of a screw working 
in an inclined cylinder, the materials being added at one 
end, water being added during the transit, thoroughly 
mixed concrete coming out at the other end. 
In Part I. of the volume is to be found every informa- 
| Fuly 30, 1885 
tion with regard to sea-works generally ; the descriptions 
and details of the construction of the Manora break-water, 
Madras harbour, and Alderney break-water among the 
many others, are extremely interesting, being as well 
written as they are good. Of the American break-waters 
described, those constructed in the large lakes, are, 
as may be expected, principally constructed of wood, 
some being bound together by means of iron ties. The 
form taken is generally crib-work, floated out to the site 
in sections, and filled with stone. Before leaving 
the subject of break-waters we will quote the author’s 
opinion on floating break-waters; this is interest- 
ing at the present time on account of the late experi- 
ments at Eastbourne and other places. He says :— 
“Various schemes have been suggested from time to 
time for arresting waves by means of floating break- 
waters moored in position. It has been imagined that 
the undulation being on the surface might be stopped or 
reduced considerably by an obstacle at or near the surface, 
and thus the cost of building up a break-water from the 
bottom could be saved; though, in the case of large 
waves, the undulatory motion is not simply superficial, 
yet, undoubtedly, the power of the waves would greatly 
diminish if the upper portions could be arrested in their 
progress ; and the gain in dispensing with a solid struc- 
ture founded on the bottom of the sea would be very 
great.” He then tells us of several forms tried which 
were not successful in reducing the waves, and in con- 
clusion says :—‘ The force of waves is so great, as indi- 
cated by its effects in moving huge masses, that no fragile 
floating moored construction could possibly oppose an 
adequate resistance. The accumulated power of the 
wind, acting through the medium of the waves, cannot 
be evaded, but must be met; and this can only be 
effectually accomplished by a solid break-water.” This 
part of the book concludes with a chapter on lighthouses, 
beacons, and buoys ; the construction and cost of all the 
important lighthouses is given and admirably illustrated. 
In Part II. “docks” receive very full consideration, 
Chapters XIX. and XX. dealing with sites, preliminary 
works for docks and dock walls; suffice it to say that all 
these are treated in such a way as to render it evident 
that the author is thoroughly master of his subject. 
In Chapters XXI. and XXII. the usual fittings pertain- 
ing to docks are discussed, their entrances and locks, 
dock-gates and caissons of all kinds thoroughly described, 
and their varied construction under different conditions 
explained. All the following chapters, which occupy the 
last 150 pages of the book, are taken up with a general, and 
in some cases a detailed, description of some of the more 
important English and foreign docks; it is needless to 
say that they are all thoroughly well treated, and the 
trade statistics are carefully given and useful comparative 
distinctions drawn. 
As a work on hydraulic engineering we can confidently 
recommend it to all those who are interested in the sub- 
ject, feeling convinced that it will be found a most useful 
book. The author has produced, and students will profit 
by, a book well written, sound, and most useful in forward- 
ing the science. Both volumes do credit to the publishers, 
the plates are good and well executed. These volumes 
ought to find a place in every technical library in the 
country. 
