Chapter XVIII: Part 18

The Deliry-Desboves dough kneader, also of French origin, and in
general use in France, consists essentially of a cast iron trough,
shaped somewhat like a basin, and turning on a vertical axis. The
kneading arms inside the trough are shaped after the pattern of a
lyre, and have the effect of first working up and then dividing the
dough right through the kneading process. Two helical blades, which
also form part of the mechanism, serve to draw out and aerate the
dough, as effectively, it is claimed, as can be done by the most
skilled operative. The force of the kneading operations can be
regulated without stopping the machine. A thoroughly kneaded dough
can, it is said, be made in this machine in twelve to fifteen minutes.

In Great Britain the type of machine that used to be most in favour
was the trough within which the kneading arms worked on horizontal
axis. The trough was either open or provided with a lid. The kneading
blades were variously shaped, but generally were more or less
straight, and were designed to both mix and aerate the dough. In some
cases the kneading blades were worked on a single axis, in others two
different sets of arms worked on two axes running parallel to one
another. Generally the kneader was geared to two speeds, the fast
motion being most suitable for sponge setting, and the earlier stages
of dough-making, while the slower motion was intended to draw out and
thoroughly aerate the dough. To discharge the dough, the trough was
tilted by means of a worm and worm wheel, the latter being secured to
the trough. Several variations of this type of kneader are still in
use. The machine known as the "Universal" kneader consists of a trough
set horizontally, within which rotate on horizontal axes a pair of
blades lying in the same plane. These blades are curved and are geared
together by means of differential spur wheels, with the object of
running the two spindles at unequal speeds. The bottom of the trough
is divided into two semi-cylindrical cavities, separated by a ridge.
Each blade plunges into its own cavity, and the action of these arms
tends, while pressing the dough against the sides and base of the
trough, to bring it quickly back towards the centre. The differential
speed has the advantage of effecting a more thorough mixing of the
dough, as it brings together pieces of dough which have not yet been
mingled, the blades pushing the dough from one cavity to the other. To
hasten the kneading process it is desirable occasionally to reverse
the motion by a turn of a hand wheel on the same shaft as the two
pulleys. This wheel governs all the motions of the blades. The trough,
which is set low, is tilted over, when the dough is ready, by an
endless chain operated by a hand winch. The effort required for this
operation is very slight, as the trough is balanced by two weights.
The action of tilting does not interfere with the blades, which
continue rotating until stopped by the hand wheel. The Universal
kneader was designed to imitate as closely as possible the action of a
pair of skilled human arms and hands, but of course works at a much
greater speed.

Another form of dough mixer which is extensively used consists simply
of a drum made of sheet steel supported by two A-shaped standards at a
sufficient height from the floor to allow a trough to be run
underneath to receive the dough when ready for the moulding board. In
this drum are two tight-fitting doors. The interior is fitted with no
blades or knives, but presents a free cylindrical space, with the sole
exception that, set not very far from the circumference, there are
several fixed rods passing from one side of the drum to the other.
These act as mixers of the dough. The door is opened and the flour and
water poured in, whereupon the door is again fastened and the drum is
made to rotate. As the rotation proceeds, the dough begins to form,
and being lifted up by the revolving drum falls by its own weight. In
this process, which is repeated again and again, the dough is caught
by and tumbled over by the rods, which act as mixers and take the
place of the revolving arms of the trough kneader. The kneading action
of the rotating arms is absent, but the steady tumbling over these
rods appears to have a thorough mixing effect, and the dough is
discharged from the drum in good condition for moulding. The time
occupied for making a dough by this apparatus varies from four to six
minutes. The advantages claimed for this machine are that it consumes
comparatively little power, and that there is not so much danger of
"felling" or over-kneading dough as in some of the machines with
revolving blades. The compactness of this rotating drum mixer, often
known as the Rotary mixer, recommends it on shipboard and in other
places where space is limited.

Dough dividers and moulders.

In the earlier days of machine bakeries the accurate dividing of
dough, and still more the moulding of loaves by mechanical means, was
considered an unattainable ideal. The first step in this direction was
made by the Lewis-Pointon dough divider and weigher, which was
intended for dividing and weighing out dough ready for the moulding
table. In an ordinary way a baker who wishes to bake a batch of
half-quartern or 2-lb. loaves scales off 2 lb. 2 oz. of dough for each
loaf. The 2 oz. are a sort of insurance against light weight. The
evaporation of moisture from dough in the oven is bound to reduce to
some extent the weight of the baked loaf, but with normally baked
bread, 2 lb. 2 oz. in the case of half-quarterns, and 4 lb. 4 oz. in
the case of quartern loaves, is sufficient to ensure full weight. As
the accurate scaling of dough requires some pains and trouble, it
would be surprising if hand scaling were always accurate. The
Lewis-Pointon machine can, it is claimed, be set to turn out lumps of
dough of the exact weight required either for 1-lb., 2-lb., or 4-lb.
loaves. The apparatus does not measure the dough by weight but by
volume by an ingenious piston arrangement. The machine when first put
on the market was a little complicated, but its mechanism has since
been simplified. It has been successfully worked on doughs of all
descriptions, ranging from the tightest to those made with 20 gallons
of water to the sack. The same firm which brought out this dough
divider has also produced a dough-moulding machine, which has a wide
range of work. In this apparatus the dough is introduced between a
trough and a revolving table at a point on the outer periphery of the
latter. The order of things observed in hand moulding is here
reversed, as the trough, unlike the hand, is fixed, while the table
revolves around a vertical axis. This table is sharply coned, and can
be made to work the dough as much or as little as may be required. In
working dough for tin or Coburg loaves only one trough is used, but
for cottage loaves two parallel troughs are fitted, one taking the
lower and the other the upper half of the loaf. In the latter case, a
single piece of dough is fed into the machine and passed through an
automatic splitter, the two portions being automatically carried into
the troughs and simultaneously delivered at the other side of the
machine ready to be put together. With doughs which require
"handing-up," two machines may be used for moulding, the dough being
automatically fed from the divider to the handing-up machine, and
after a short proof passed through the finisher. But the moulding
machine may also be used as a "hander-up."

Another ingenious dough moulder, known as the Baker-Callow, works on a
rather different principle. Here the pieces of dough coming from the
divider are fed into the moulder by a canvas band, and are worked
between a large cylindrical roller and a vertically running canvas and
leather belt. To prevent pieces from dropping through, and to assist
the moulding process, a smaller roller is placed under and between the
cylindrical roller and canvas belt. A wooden puncher also assists in
working the loaves, which are finished by being rolled between a band
and a special shaped wooden moulding. This machine delivers the dough
in spherical shaped pieces. If intended for cottage bread they are at
once placed on the dough table at the side, and one piece is put on
the top of the other ready for the oven. It is claimed the machine
will deal equally well with large and small pieces at the same time,
so that the tops and bottoms can be made together. Should the machine
be intended for tinned bread, a special attachment is used, into which
the spherical pieces are delivered from the machine and rolled into
cylindrical shapes, ready to be dropped into the pan. A capacity of
sixty loaves per minute is claimed for this moulder.

_Ovens._--The ordinary baker's oven is a vaulted chamber, about 10 ft.
in length, by 8 ft. in width and 30 in. in height; it is constructed
of brick or stone, and has a small door in front through which the
oven is charged (by means of a "peel" or long wooden shovel) and the
batch withdrawn. The furnace and fire-grate are often placed at the
side of the oven door, but with the oldest ovens, which were heated by
wood, there generally was only one door for the fuel and for the
bread. Whether the furnace is heated by coal, as is usual in England,
or by coke, as is often the case in Scotland, the oven mouth remains
in the bakehouse itself; hence the stoking and scuffling must be
carried out within the bakehouse. This is in many ways objectionable.
For one thing, the fuel must almost of necessity be kept in the
bakehouse itself, and it is obvious that the products of combustion
are liable to get into the oven. In the old type of oven a flue was
frequently placed on the other side of the furnace door, both furnace
and flue being on the front of the oven. After firing the furnace, the
oven is allowed to "lie down" for a certain time, and secure an even
distribution of heat. The furnace and flue are then shut, and the oven
charged, the batch being baked by the heat stored within the oven
chamber. With ovens of this type, each batch of bread requires a
separate firing. This kind of oven has undergone several improvements
of detail, but the principle of internal heating, that is, of firing
the furnace inside the bakehouse, has remained unchanged.

A new era in bakers' ovens began about the middle of the 19th century
with the introduction of the "Perkins" oven, a system which, with
slight modifications, has persisted till to-day. In this oven the
baking chamber is heated by steam pipes. The latter consist of tubes
of iron or mild steel which are partly filled with water and are
hermetically sealed by welded ends. The pipes are arranged in two
parallel rows, the one at the crown and the other at the sole of the
oven. The pipes project at one end into the furnace, which is set at
the back of the oven and is usually outside the bakehouse. This is
termed an externally heated oven. As the ends of the pipes get red hot
the water is converted into superheated steam, which being under high
pressure soon raises the chamber to baking heat, say 450 deg. to 500
deg. F. In an oven of this description the heat can be continuously
maintained, and batch after batch can be baked without refiring. The
only drawback is that a flash heat cannot be raised. In another type
of externally fired oven the heat is conveyed by flues placed at the
bottom and top of the oven, which discharge into a chimney. Excellent
results have been attained with ovens of this kind. The distribution
of the heat can be well regulated; for instance, it is quite possible
to build ovens to be cooler at the back than front, an arrangement
which is useful when the bread is withdrawn by means of a hand peel.
As the baker has to withdraw each loaf one at a time, it is clear that
the withdrawal of the batch through the oven door must take time,
probably not less than half-an-hour. Hence the bread drawn from near
the oven's mouth may be underbaked as compared with that at the back
of the chamber. The latter, on the other hand, may be overbaked and
deficient in weight.

By means of a draw-plate, however, an oven can be expeditiously
charged. This appliance consists of a sliding plate or tray, mounted
on wheels running on rails, which is drawn out of the oven loaded with
bread, and then returned. The plate itself is often made of iron, but
one well-known oven is fitted with a withdrawable iron frame, in which
are laid, edge to edge, tiles of a special make, which are cemented in
place, and form a continuous baking surface. This seems an excellent
arrangement, as the baker has all the advantages of a brick oven, that
is to say, his bread is baked both on top and bottom by heat evolved
from tiled surfaces, and the undoubted drawbacks incidental to baking
bread on an iron surface are avoided. A draw-plate fitted to an oven
capable of baking a batch made from a sack (280 lb) of flour can be
run out, charged and run in again, in about two minutes. The
draw-plate has the incidental advantage, by expediting the loading and
discharge of the oven, of ensuring a more uniform baking of the batch,
and therefore of minimizing the loss of weight. Some bakers have gone
so far as to estimate the saving in this respect from the use of a
draw-plate at half an ounce per 2-lb. loaf. With decker ovens a double
draw-plate may be used, the feet of the pedestal supporting the upper
draw-plate running on a rail outside, but parallel to the rail on
which the lower draw-plate runs. This arrangement, however, is more
applicable to small than large ovens. Or the lower oven may be fitted
with a draw-plate while the upper oven is served with a peel. The
draw-plate being at a lower level than the sole of an ordinary oven,
the upper deck may be worked with a peel without much difficulty.

The _decker_ oven is, as its name implies, an oven built over another
oven: in fact, sometimes a tier of three ovens is employed, placed one
above the other. The object is to secure a double or treble baking
surface without a very much larger outlay on fuel than would be
necessary for one oven. It is easy to understand that a double or
three decker oven might be constructed under conditions where it would
be impossible to place two or three ordinary ovens side by side.
Practical bakers are somewhat divided as to the actual economy of the
decker system; possibly it is a question of management. The upper oven
is heated by the gases which have passed under the oven beneath. A
double-decker oven on the flue principle could be heated by three
flues, one beneath the lower oven, another passing between the crown
of the lower and the sole of the top oven, and the third over the
crown of the upper oven. If a third oven were built over the second,
then a fourth flue would pass over the crown of the third and top
oven. In such an arrangement of flues the distribution of heat to the
ovens would be fairly equal, but no doubt the lower oven would be the
hottest. In addition to the flues, which should be straight and
accessible for cleaning, there ought also to be auxiliary flues by
which heat may be allowed to pass dampers to the upper portions of the
series of ovens. In this way the heat of the upper oven or ovens can
be regulated independently to a great extent of the bottom oven. The
power of regulating the heat of the ovens is very necessary, because a
baker doing what is called a mixed trade, that is to say, producing
cakes and pastry in addition to bread, must work his ovens at varying
temperatures. Cakes cannot be baked at the heat (about 450 deg. F.)
required by a batch of household bread. The richest fancy goods, such
as wedding and Christmas cakes, require the coolest ovens. Flue ovens
are best worked with coke, as coal is apt to choke the flues; retort
coke is recommended in place of oven coke. An oven should be fitted
with some kind of thermal register, and both high-temperature
thermometers and pyrometers are used for this purpose. (G. F. Z.)

BREADALBANE, JOHN CAMPBELL, 1ST EARL OF (c. 1636-1717), son of Sir John Campbell of Glenorchy, Bart., and of the Lady Mary Graham, daughter of William, earl of Airth and Menteith, was born about 1636. He took part in the abortive royalist rising under Glencairn in 1654, and was one of those who urged Monk to declare a free parliament in England to facilitate the restoration. He sat in the Scottish parliament as member for Argyllshire from 1669 to 1674. As principal creditor he obtained in October 1672, from George, 6th earl of Caithness, a conveyance of his dignities, lands and heritable jurisdictions; and after the latter's death he was created on the 28th of June 1677 earl of Caithness and viscount of Breadalbane. In 1678 he married the widowed countess of Caithness, an economical step which saved him the alimentary provision of 12,000 merks a year he had covenanted to pay. In 1680 he invaded Caithness with a band of 700 men and defeated and dispossessed the earl's heir male. The latter, however, was subsequently confirmed in his lands and titles, and Campbell on the 13th of August 1681 obtained a new patent with the precedency of the former one, creating him earl of Breadalbane and Holland, viscount of Tay and Paintland, Lord Glenorchy, Benederaloch, Ormelie and Weick in the peerage of Scotland, with special power to nominate his successor from among the sons of his first wife. In 1685 he was a member of the Scottish privy council. Though nominally a Presbyterian he had assisted the intolerant and despotic government of Lauderdale in 1678 with 1700 men. He is described as having "neither honour nor religion but where they are mixed with interest," as of "fair complexion, of the gravity of the Spaniard, cunning as a Fox, wise as a Serpent and supple as an Eel."[1] He was reputed the best headpiece in Scotland.[2] His influence, owing to his position and abilities, was greater than that of any man in Scotland after Argyll, and it was of high moment to King William to gain him and obtain his services in conciliating the Highlanders. Breadalbane at first carried on communications with Dundee and was implicated in the royalist intrigue called the "Montgomery plot," but after the battle of Killiecrankie in July 1689 he made overtures to the government, subsequently took the oath of allegiance, and was entrusted with a large sum of money by the government to secure the submission of the clans. On the 30th of June 1691 he met the Jacobite chiefs and concluded with them secret articles by which they undertook to refrain from acts of hostility till October, gaining their consent by threats and promises rather than by the distribution of the money entrusted to him, the greater part of which, it was believed, he retained himself. When asked to give an account of the expenditure he replied: "The money is spent, the Highlands are quiet, and this is the only way of accounting between friends."[3]

On the 27th of August a proclamation was issued offering indemnity to all those who should submit and take the oath of allegiance before the 1st of January 1692, and threatening all those who should refuse with a military execution and the penalties of treason. All the chiefs took the oath except MacIan, the chief of the MacDonalds of Glencoe, who postponed his submission till the 31st of December, and was then prevented from taking the oath till the 6th of January 1692 through the absence of a magistrate at Fort William, whither he had repaired for the purpose. This irregularity gave Breadalbane an immediate opportunity of destroying the clan of thieves which had for generations lived by plundering his lands and those of his neighbours. Accordingly, together with Argyll and Sir John Dalrymple (afterwards Lord Stair), Breadalbane organized the atrocious crime known as the "Massacre of Glencoe," when the unfortunate MacDonalds, deceived by assurances of friendship, and at the moment when they were lavishing their hospitality upon their murderers, were butchered in cold blood on the 13th of February 1692. Breadalbane's astuteness, however, prevented the disclosure of any evidence against him in the inquiry afterwards instituted in 1695, beyond the deposition of a person who professed to have been sent on Breadalbane's behalf to obtain a declaration of his innocence from MacIan's sons, who had escaped. The discovery of his former negotiations with the Jacobite chiefs caused his imprisonment in Edinburgh Castle in September, but he was released when it was known that he had been acting with William's knowledge.

Breadalbane did not vote for the Union in 1707, but was chosen a representative peer in the parliament of Great Britain of 1713-1715. His co-operation with the English government in securing the temporary submission of the Highlands was inspired by no real loyalty or allegiance, and he encouraged the attempted French descent in 1708, refusing, however, to commit himself to paper. On the occasion of the Jacobite rising in 1715 he excused himself on the 19th of September from obeying the summons to appear at Edinburgh on the ground of his age and infirmities; but nevertheless the next day visited Mar's camp at Logierait and afterwards the camp at Perth, his real business being, according to the Master of Sinclair, "to trick others, not to be trickt," and to obtain a share of the French subsidies. He had taken money for the whole 1200 men he had promised and only sent 300. His 300 men were withdrawn after the battle of Sheriffmuir, and his death, which took place on the 19th of March 1717, rendered unnecessary any inquiry into his conduct. He married (1) Mary, daughter of Henry Rich, 1st earl of Holland, by whom he had two sons, Duncan, styled Lord Ormelie, who was passed over in the succession, and John, and earl of Breadalbane; (2) Mary, daughter of Archibald, marquis of Argyll, and widow of George, 6th earl of Caithness, by whom he had one son, Colin. By Mrs Mildred Littler, who has sometimes but probably in error been named as his third wife, he had a daughter, Mary.

JOHN CAMPBELL, 2nd earl of Breadalbane (1662-1752), an eccentric nobleman, who was known as "Old Rag," was succeeded by his only son, John (c. 1696-1782). This earl was a diplomatist, being British ambassador to Denmark and to Russia, and a politician, being for a long time a member of the House of Commons and a supporter of Sir Robert Walpole, in addition to holding several official positions. All his sons having predeceased their father, the title passed on his death, on the 26th of January 1782, to a cousin, John (1762-1834), who became 4th earl and was created a British peer as marquess of Breadalbane in 1831. His son John, the 2nd marquess (1796-1862), a prominent leader of the Free Church during the ecclesiastical disputes in Scotland, died without sons in November 1862. The marquessate now became extinct, but the Scottish earldom passed to a cousin John Alexander (1824-1871), whose son and successor, Gavin (b. 1851), was created marquess of Breadalbane in 1885.

FOOTNOTES:

[1] _Memoirs_ of John Macky (Roxburghe Club, 1895), 121.

[2] _Corr. of Col. N. Hooke_ (Roxburghe, Club, 1870), i. 49.

[3] Note by Sir W. Scott in Sinclair's _Mem. of Insurrection in
Scotland_ (Abbotsford Club, 1858), 185.

BREADALBANE, a large district of Perthshire, Scotland, bordered N. by Atholl, E. by Strathtay, S. by Strathearn and W. by the districts of Argyll and Lorne, and occupying some 1020 sq. m. Most of the surface is mountainous, Ben Lawers (3984 ft.), Ben More (3843), and Ben Lui (3708), being the principal hills. Loch Tay is the chief lake, and among the rivers are the Orchy, Dochart, Lochay, Lyon, Almond and the Tay (during the early part of its course). Population mostly centres in Aberfeldy, Fortingal, Kenmore and Killin. The soil is not cultivable excepting in some of the glens and straths. Game is plentiful, the lakes and rivers afford good sport, and the deer forests and shootings are valuable. The district has given the titles of earl and marquess to the Campbells of Glenorchy.

BREAD-FRUIT. This most important food staple of the tropical islands in the Pacific Ocean is the fruit of _Artocarpus incisa_ (nat. ord. Moraceae). The tree attains a moderate height, has very large, acutely lobed, glossy leaves, the male flowers in spikes, and the female flowers in a dense head, which by consolidation of their fleshy carpels and receptacles form the fruit. The fruit is globular in shape, about the size of a melon, with a tuberculated or (in some varieties) nearly smooth surface. Many varieties of the tree are cultivated, the fruits of some ripening numerous seeds, which are eaten as chestnuts; but in the best kinds the seeds are aborted, and it is only these that are highly prized as vegetables. The tree is a native of the South Sea Islands, where its fruit occupies the important position that is held by cereals in temperate latitudes. The fruit, which on distinct varieties ripens at different periods, affording a nearly constant supply throughout the year, is gathered for use just before it ripens, when it is found to be gorged with starchy matter, to which its esculent value is due. It may be cooked and prepared for use in a great variety of ways, the common practice in the South Sea Islands being to bake it entire in hot embers, and scoop out the interior, which when properly cooked should have a soft smooth consistence, fibrous only towards the heart, with a taste which has been compared to that of boiled potatoes and sweet milk. Of this fruit A.R. Wallace, in his _Malay Archipelago_, says: "With meat and gravy it is a vegetable superior to anything I know either in temperate or tropical countries. With sugar, milk, butter or treacle it is a delicious pudding, having a very slight and delicate but characteristic flavour, which, like that of good bread and potatoes, one never gets tired of." In the Pacific Islands the fruit is preserved for use by storing in pits, where the fruits ferment and resolve themselves into a mass similar in consistency to new cheese, in which state they emit an offensive odour; but after baking under hot stones they yield a pleasant and nutritious food. Another and more common method of preserving the fruit for use consists in cutting it into thin slices, which are dried in the sun. From such dried slices a flour is prepared which is useful for the preparation of puddings, bread and biscuits, or the slices are baked and eaten without grinding. The tree yields other products of economic value, such as native cloth from the fibrous inner bark of young trees; the wood is used for canoes and articles of furniture; and a kind of glue and caulking material are obtained from the viscid milky juice which exudes from incisions made in the stem.

Fig. 1. Branch reduced about a 6th natural size, with cuneate-ovate
pinnatifid leaves, male flowers in a club-shaped deciduous catkin,
and female flowers in rounded clusters.
Fig. 2. Transverse section of the male spike with numerous flowers.
Fig. 3. Male flowers.
Fig. 4. Single male flower separated, with a perianth in 2 segments
and a single stamen.
Fig. 5. Female flowers.
Fig. 6. Single female flower separated, with ovary, style and bifid
stigma.
Fig. 7. Ovary.
Fig. 8. Ovary laid open to show the ovule.
Fig. 9. A variety of the ovary with 2 loculaments.
Fig. 10. Transverse section of a bilocular ovary.]

The bread-fruit is found throughout the tropical regions of both hemispheres, and its first introduction into the West Indies is connected with the famous mutiny of the "Bounty," and the remarkable history of a small company of the mutineers at Pitcairn Island. Attention was directed to the fruit in 1688 by Captain Dampier, and later by Captain Cook, who recommended its transplantation to the West Indian colonies. In 1787 the "Bounty" was fitted out under command of Lieutenant William Bligh (q.v.) to proceed to Tahiti to carry plants thence to the West Indian Islands; and it was after the cargo had been secured and the vessel was on her way that the mutiny broke out, and Lieutenant Bligh and some of his crew were turned adrift in a small boat in the open sea. The mutineers returned with the vessel to Tahiti, whence a number of them, with a few native men and women, sailed to the desolate and lone islet of Pitcairn. Lieutenant Bligh ultimately reached England, and was again commissioned to undertake the work of transplanting the plants, which in the year 1792-1793 he successfully accomplished.

A somewhat similar but inferior fruit is produced by an allied species, the Jack or Jak, _Artocarpus integrifolia_, growing in India, Ceylon and the Eastern Archipelago. The large fruit is from 12 to 18 in. long by 6 to 8 in. in diameter, and is much eaten by the natives in India. This tree is chiefly valuable on account of its timber, which has a grain very similar to mahogany, and although at first light-coloured it gradually assumes much of the appearance of that wood.

BREAKING BULK, a nautical term for the taking out of a portion of the cargo of a ship, or the beginning to unload; and used in a legal sense for taking anything out of a package or parcel, or in any way destroying its entirety. It was thus important in connexion with the subject of bailment, involving as it did the curious distinction that where a bailee received possession of goods in a box or package, and then sold them as a whole, he was guilty only of a breach of trust, but if he "broke bulk" or caused a separation of the goods, and sold a part or all, he was guilty of felony. This distinction was abolished by the Larceny Act 1861, which enacted that whoever, being a bailee of any chattel, money or valuable security, should fraudulently take or convert the same to his own use, or the use of any person other than the owner, although he should not break bulk or otherwise determine the bailment, should be guilty of larceny (s. 3).

BREAKWATER. When a harbour (q.v.) is proposed to be established on an exposed coast, whether for naval or commercial purposes, to provide a protected approach to a port or river, or to serve as a refuge for vessels from storms, the necessary shelter, so far as it is not naturally furnished by a bay or projecting headlands, has to be secured by the construction of one or more "breakwaters." These breakwaters, having to prevent the waves that beat upon the coast from reaching the site which they are designed to protect, must be made sufficiently strong to withstand the shocks of the waves during the worst storms to which they are exposed. It is therefore essential, before constructing a breakwater, to investigate most carefully the force, periods and duration of the winds from the quarters to which the work will be exposed, the distance of any sheltering land from the site in the most stormy direction, the slope of the beach and the depth of the sea in the neighbourhood of the shore, and the protection, if any, afforded by outlying shoals or sandbanks. In a tidal sea, the height required for a breakwater is affected by the amount of tidal range; and the extent of breakwater exposed to breaking waves depends upon the difference in level between low and high water. The existence, also, of any drift of sand or shingle along the shore must be ascertained, and its extent; for the projection of a solid breakwater out from the shore is certain to affect this littoral drift, which, if large in amount, may necessitate important modifications in the design for the harbour.

Winds.

Observations of the force and prevalence of the winds from the different quarters at the various periods of the year, and the instruments by which they are recorded, belong to the science of meteorology; but such records are very valuable to the maritime engineer in indicating from which directions, open to the sea, the worst storms, and, consequently, the greatest waves, may be expected, and against which the most efficient shelter has to be provided. Moreover, it is necessary, for constructing or repairing a breakwater, to know the period of the year when the calmest weather may be safely anticipated, and also the stormy season during which no work should be attempted, and in preparation for which unfinished works have to be guarded by protective measures. In the parts of the world subject to periodical winds, such as the monsoons, the direction and force of the winds vary with remarkable regularity according to the seasons; and even such uncertain occurrences as hurricanes and cyclones generally visit the regions in their track at definite periods of the year, according to the locality. Even in western Europe, where the winds are extremely variable, violent gales are much more liable to beat upon the western and northern coasts in the winter months than at any other period of the year; whilst the calmest weather may be expected between May and August.

Waves.

The size of waves depends upon the force of the wind, and the distance along which it blows continuously, in approximately the same direction, over a large expanse of ocean. The greatest waves are, accordingly, encountered where the maximum distance in a certain direction from the nearest land, or, as it is termed, the "fetch," coincides with the line travelled by the strongest gales. The dimensions, indeed, of waves in the worst storms depend primarily on the extent of the sea in which they are raised; though in certain seas they are occasionally greatly increased by the exceptional velocities attained by hurricanes and typhoons, which, however, are fortunately restricted to fairly well defined and limited regions. Waves have been found to attain a maximum height of about 10 ft. in the Lake of Geneva, 17 ft. in the Mediterranean Sea, 23 ft. in the Bay of Biscay, and 40 ft. in the Atlantic Ocean; whilst waves of 50 to 60 ft. in height have been observed in the Pacific Ocean off the Cape of Good Hope, where the expanse of sea reaches a maximum, and the exposure to gales is complete. The length of large waves bears no definite relation to their height, and is apparently due, in the long waves often observed in exposed situations, to the combination of several shorter waves in their onward course, which is naturally dependent on the extent of the exposure. Thus waves about 560 ft. in length have been met with during severe gales in the Atlantic Ocean; whilst waves from 600 to 1000 ft. long are regarded as of common occurrence in the Pacific Ocean during storms.

The rate of transmission of the undulation also varies with the exposure; for the ordinary velocity of the apparent travel of waves in storms has been found to amount to about 22 m. an hour in the Atlantic Ocean, and to attain about 27 m. an hour off Cape Horn. The large waves, however, observed in mid-ocean do not reach the coast, because their progress is checked, and their height and length reduced, by encountering the shelving sea-bottom, which diminishes the depth of water on approaching the shore; and the actual waves which have to be arrested by breakwaters depend on the exposure of the site, the existence of continuous deep water close up to the shore, and the depth in which the breakwater is situated. On the other hand, the height, and, consequently, the destructive force of waves, is increased on running up a funnel-shaped bay, by the increasing concentration of the waves in the narrowing width, just as the tidal range of a moderate tidal current is much augmented by its passage up the Bay of Fundy, or up the Bristol Channel into the Severn estuary, or by filling the shallow enclosed bay of St Malo. This effect is intensified when the bay faces the direction of the strongest winds. Thus at Wick a mass of masonry weighing 1350 tons, placed at the head of the breakwater projecting half-way across the bay and facing the entrance, was moved by the waves during a violent storm; and a portion of Peterhead breakwater, weighing 3300 tons, was shifted 2 in. in 1898, indicating a wave-stroke of 2 tons per sq. ft. Southwesterly gales, blowing up the Gulf of Genoa, cause large waves to roll into the bay, reaching a height of about 21 ft. in the worst storms.

Where outlying sandbanks stretch in front of a coast, as for instance the Stroombank in front of Ostend and the adjacent shore, and the sandbanks opposite Yarmouth sheltering Yarmouth Roads, large waves cannot approach the land, for they break on the sandbanks outside. Waves, indeed, always break when, on running up a shoaling beach, they reach a depth approximately equal to their height; and the largest waves which can reach a shore protected by intervening sandbanks, are those which are low enough to pass over the banks without breaking.

The force of the wind, as transmitted by degrees to the sea, is manifested as a series of progressing undulations without any material displacement of the body of water, each undulation transmitting its accumulated force to the next in the direction the wind is blowing, till at last, on encountering an obstacle to its onward course, each wave, no longer finding any water to which to communicate its energy, deals a blow against the obstacle proportionate to its size and rate of transmission; or on reaching shoal water near the shore, the undulation is finally transformed into a breaking wave rushing up the sloping beach. till, on its energy being spent, it recoils back to the sea down the beach. A breaking wave concentrates its transmitted force on a portion of the water forming the undulation, which, consequently, strikes a more powerful blow over a limited area against any structure than the more distributed shock of a simple undulation beating against a vertical wall. Moreover, the recoil of broken waves down a sloping beach or rubble mound produces a greater scour than the simple reflection of an undulation from a vertical wall, especially where the depth is sufficient to provide a cushion of water below the undulation, protecting the toe of the wall from the wash of recoil.

_Types of Breakwaters_.--There are three distinct types of breakwaters:--(1) A simple rubble or concrete-block mound; (2) a mound for the bottom portion, surmounted on the top by a solid superstructure of masonry or concrete; and (3) an upright-wall breakwater, built up solid from the sea-bottom to the top. The second type forms a sort of combination of the first and third types; and each type presents several varieties. In a few harbours, two different types have been adopted for different situations at the same place; but generally the choice of type is determined by the materials available at the site for the construction of the breakwater, the nature of the sea-bottom and the depth into which the breakwater has to be carried.

Rubble mound.

1. _Rubble and Concrete-Block Mound Breakwaters._--A rubble mound
consists merely of a mass of rubble stone, just as it is obtained from
a neighbouring quarry, tipped into the sea along a predetermined line,
till the mound emerges out of water. The rubble stone is deposited,
either from barges, as adopted for the construction of the detached
breakwater sheltering Plymouth Bay, or from wagons, having hinged
opening flaps at the bottom for dropping their load, run out from the
shore along staging erected in the proposed line, according to the
method employed for the outer breakwater enclosing Portland Harbour,
and the north-east breakwater at Colombo Harbour. The mound thus
deposited is gradually consolidated under the action of the sea; and a
tolerably stable form is by degrees attained by continued deposits of
stone. This system of construction is very wasteful of materials, and
can only be resorted to where extensive quarries close at hand are
able to furnish readily and cheaply very large quantities of stone,
especially where, as at Portland and Table Bay, convict labour has
been advantageously utilized in quarrying. When the site is very
exposed, the large waves in storms, dashing over a rubble-mound
breakwater, carry the stones on the top, if unprotected, over on to
the harbour slope, and in recoiling down the outer slope, draw down
the stones on the face, so that the top and sea slope of the mound
need replenishing with a fresh deposit of stones after severe storms.

Under the action of the breaking and recoiling waves, the mound
assumes a very flat slope on the sea side, from a few feet above
high-water down to several feet below low-wafer level (fig. 1). The
flatness of the sea slope depends on the exposure of the site, and the
limited size of the stones covering the outer portion of the mound;
and its extent increases with the range of tide, as a large tidal rise
exposes a greater length of slope to the action of the waves. This
flattening of the sea slope greatly increases the amount of stone
required for a rubble-mound breakwater, in proportion to the exposure
and the range of tide; and the amount is also affected, but in a
proportionately minor degree, by the depth in which the breakwater is
situated. In order to avoid the injuries to which an ordinary rubble
mound is subjected by waves, certain methods have been devised for
protecting the top and sea slope of the mound. For instance, the upper
portion of Plymouth breakwater has been covered over by granite paving
set in cement, to diminish the displacement of the stones by the
waves. Frequently, on the continent of Europe, rubble mounds have been
formed of materials so sorted that the smallest stones are placed in
the centre of the lower part of the mound, and covered over along the
slopes and top by layers of larger stones, increasing in size towards
the outer part of the mound, so that the largest stones obtainable are
deposited on the outside, and especially on the top and sea slope of
the mound. This is, no doubt, theoretically the correct method of
construction of rubble mounds exposed to the sea; but it involves a
considerable amount of trouble and expense.

Concrete blocks with rubble mound.

Practically the chief point of importance is to cover the outer slope
and the top of the mound with the largest stones that can be procured,
and where large stones are not readily obtainable concrete blocks
furnish a very convenient substitute. These blocks are generally
deposited as the outer covering on the top and sea slope of a rubble
mound, as for example at the mound breakwaters in deep water
sheltering Algiers harbour, and at the French parts of Cette and Bona
on the Mediterranean; whilst they furnish the protection of the top
and upper part of the sea slope of the rubble-mound extension of
Marseilles breakwater down to 20 ft. below sea-level. At Alexandria,
concrete blocks compose the outer half of the mound, sheltering the
inner half consisting of small rubble (fig. 2); at Biarritz the mound
breakwater is formed mainly of concrete blocks, with rubble stone
filling the interstices and on the top; whereas at the outer end of
the western breakwater at Port Said, protecting the entrance to the
Suez Canal, a bottom layer of rubble is surmounted by concrete blocks.
These blocks are generally deposited at random; but at Cette (fig. 3),
and at the breakwater in deep water at Civita Vecchia, the concrete
blocks covering the rubble have been laid in stepped, horizontal
courses. This arrangement necessitates more care and better appliances
in construction; but, in compensation, the blocks so placed are less
exposed to disturbance and injury by the waves.

Concrete blocks possess the great advantages for breakwaters that they
can be made wherever sand and shingle can be procured, and of a size
only limited by the appliances which are available for handling them.
In fact, in places where stone of any kind is difficult to procure at
a reasonable cost, as for instance at Port Said, concrete blocks are
indispensable for the construction of breakwaters. Large concrete
blocks, moreover, by enabling a comparatively steep slope to be formed
with them on the sea side of a mound breakwater, reduce considerably
the amount of materials required, especially at exposed sites, and
also for breakwaters extended into deep water, such as those of
Algiers and Marseilles.

Concrete block mound.

Occasionally, in the absence of suitable rubble stone, a mound
breakwater has been formed entirely with concrete blocks; and of this
the main portion of the western breakwater at Port Said furnishes a
notable example (fig. 4). Sometimes, in exposed situations, the mounds
of the composite type of breakwaters have been constructed exclusively
with concrete blocks, such, for instance, as in the curved breakwater
protecting the outer harbour at Leghorn, and in the central breakwater
in deep water sheltering the harbour of St Jean de Luz, and directly
facing the Bay of Biscay. These large concrete blocks are deposited by
cranes from staging, tipped into the sea from a sloping platform on
barges, or floated out between pontoons, or slung out from floating
derricks. This last method proved so expeditious for the upper blocks
at Alexandria, that, in conjunction with the tipping of the lower
blocks from the inclined planes on the decks of barges and the deposit
of the rubble from hopper barges, provided also with side flaps for
the higher portions, the detached breakwater, nearly 2 m. long,
sheltering a very spacious harbour, was constructed in two years
(1870-1872). Sometimes, when a mound breakwater has been raised out of
water, advantage is taken of a calm period of the year and a low tide
to form large blocks of concrete within timber framing on the top of
the mound, so as to provide a very efficient protection.

The large masses composing mound breakwaters give them great stability
against the attacks of the sea; and, moreover, the wide base of the
mounds enables them to be deposited on a sandy or silty sea-bottom,
without any fear of settlement or undermining. A mound breakwater,
however, has the disadvantages of requiring a large amount of
material, and of occupying a wide space on the bed of the sea, more
especially where the mound consists of rubble stone and is in deep
water, so that the system, though simple, is costly, and is unsuited
for harbours where the available space to be sheltered is limited.
Nevertheless, a mound breakwater can be rapidly constructed by the
employment of a large number of barges; and by the adoption of large
concrete blocks, the quantity of materials and the space occupied by
the mound can be considerably reduced. This form of breakwater, with
its long outer slope exposed to breaking waves, particularly where the
tidal range is considerable, is, indeed, more subject to frequent
small injuries than the other types, but they are readily repaired;
and a mound is not generally liable to the serious breaches which
occasionally are formed in solid superstructures and upright walls in
exceptional storms.

2. _Breakwaters formed of a Mound surmounted by a Superstructure._--The
second type of breakwater consists of a mound, composed of rubble or
concrete blocks, or generally a combination of the two, carried up from
the sea-bottom, on the top of which some form of solid superstructure
is erected. This superstructure reduces considerably the amount of
materials required (which, on account of the slopes of the mound,
increases rapidly with the height) in proportion to the depth at which
the superstructure is founded; and the solid capping on the mound
serves also to protect the top of the mound from the action of the
waves. In the case, however, of a mound breakwater, portions of the
highest waves generally pass over the top of the mound, and also to
some extent expend their force in passing through the interstices
between the blocks; whereas a superstructure presents a solid face to
the impact of the waves. A superstructure, accordingly, must be very
strongly built in proportion to the exposure, and also to the size of
the waves liable to reach it, which depends upon the height and
flatness of the slope of the mound just in front of it on the sea side.
Special care, moreover, has to be taken to prevent the superstructure
from being undermined; for the waves in storms, dashing up against this
nearly vertical, solid obstacle, tend in their recoil down the face to
scour out the materials of the mound at the outer toe of the
superstructure, and thereby undermine it, especially where the
superstructure is founded on the mound near low-water level, and there
is, therefore, no adequate cushion of water above the mound to diminish
the effect of the recoil on the foundation.

The mound constituting the lower portion of the composite type of
breakwater has been formed in the same varied way as simple mound
breakwaters, namely, of rubble, sorted rubble, rubble protected by
concrete blocks, and wholly of concrete blocks. The only differences
introduced in the mound in this case are, that it is not carried up so
high, that the top portion covered by the superstructure needs no
further protection, and that special protection has to be provided on
the slope of the mound adjacent to the outer toe of the
superstructure.

Superstructures.

The forms of the superstructures exhibit considerable variations,
ranging from a few concrete blocks laid in courses on the top of the
mound, or a paving furnishing a quay protected by a narrow parapet
wall on the sea side, up to a large, solid structure, only differing
from an upright-wall breakwater in being founded upon a mound, instead
of on the sea-bottom. Notwithstanding, however, this great variety in
design, these breakwaters may be divided into two distinct classes,
namely, breakwaters having their superstructures founded at or near
low-water level, and breakwaters with superstructures founded some
depth below low water. The object in the first case is to lay the
foundations of the superstructure on the mound at the lowest level
consistent with building a solid structure with blocks set in mortar,
out of water, in the ordinary manner; and, in the second case, to stop
the raising of the mound at such a depth under water as to secure it
from displacement by the waves. In fact, the solidity and facility of
construction of the superstructure were the primary considerations in
the older form of breakwater; whereas the stability of the mound and
the avoidance of the undermining of the superstructure have been
regarded as the most important provisions in the more modern form.

Superstructures at low-water level.

Well-known examples of breakwaters formed of a rubble mound surmounted
by a superstructure founded at or near low water or sea-level, are
furnished by Cherbourg and Holyhead breakwaters, the inner breakwater
at Portland, and the breakwaters at Marseilles, Genoa, Civita Vecchia,
Naples, Trieste and other Mediterranean ports. The very exposed
breakwater at Alderney was commenced on this principle about the
middle of the 19th century; and the outer breakwaters at Leghorn and
St Jean de Luz have superstructures founded at low water on
concrete-block mounds.

The long, detached breakwater sheltering the series of basins formed
by wide projecting jetties along the sea coast at Marseilles (see
DOCK), is a typical instance of a breakwater where a quay has been
formed on the top of a sorted rubble mound, sheltered on the sea side
by a high wall, or narrow superstructure, founded at sea-level, and
protected on the sea slope of the mound from undermining by large
concrete blocks deposited at random (fig. 5). In this case the quay
has been rendered accessible for vessels on the harbour side by a quay
wall, formed of concrete blocks deposited one above the other,
providing a vertical face to a depth of about 22-3/4 ft. below
sea-level; and a similar arrangement has been adopted at Trieste, and
in a less effective manner at Civita Vecchia and Naples. At
Marseilles, however, when the breakwater reached great depths, the
quay was abandoned on account of the increased exposure, and the
extension made of a simple rubble mound, protected on the sea side,
from the top down to 20 ft. below sea-level, by large concrete blocks
deposited at random.