The illustrated exhibitor: a tribute to the world's industrial jubilee (London, 1851)

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THE ILLUSTRATED EXHIBITOR.

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duction of a transept, is the building now standing in
Hyde-park.

The Committee, in their report on the competition de-
signs for the building, most truly said that " amongst the
several classes of designs, the practical character of our
own countrymen, as might have been expected, has been
remarkably illustrated in some very striking and simple
methods of construction, suited to the temporary purposes
of the building, due attention having been paid to the
pecuniary means allotted to this part of the undertaking;"
an expression which applies equally well to the present
building, which must be considered to illustrate, in a re-
markable manner, the constructive skill and commercial
enterprise of our country.

The size of the building must strike the most obtuse,
particularly as it extends principally in one direction,
stretching out to a length of more than a third of a mile.
This is a tangible idea; but it is more difficult to form an
adequate notion of the total area enclosed and roofed over,
which is more than 19 acres. Of the amount of labour
necessary to erect a wind and weather tight building of
such immense extent, no idea whatever can be formed from
the general mass; it is only by minutely examining all
the parts of a small section, and then observing how many
hundred times such a portion is repeated, that the labour
can be estimated. Those who will take the trouble thus
to investigate the building will soon discover that, although
vast in extent, in design it is exceedingly simple. Its
greatest length is 1,848 feet, and greatest width 456 feet,
and it is placed so that the length is nearly in the direction
east and west: and as regards the structural parts of the
building, the interior forms one undivided space, the roof
and galleries resting entirely on insulated supports, the
sub-divisions being merely made for the convenience of
arranging and displaying the articles exhibited. As the
exterior is merely the expression of the interior arrange-
ment, it will be well to take the latter first. This may be
described as consisting of a series of avenues, running the
whole length of the building, and varying symmetrically on
either side of the centre both in width and height. The
centre one is 72 feet wide, and 66 feet high; on either
side of this an avenue, 24 feet wide, rises to the same height;
and, further outwards, avenues, alternately 48 feet and 24
feet wide, extend in parallel lines, filling up the outline of
the building. ^The height of the first pair of these on each
side, is 43 feet, and the remainder are 23 feet high, from
the floor to the roof.

The avenues thus described (altogether 11 in the whole
width of the building) are formed by rows of slender
columns placed at the distance of 24 feet apart, and rising
in one, two, and three stories, to support the roof, at the
three respective heights mentioned; it will be seen, there-
fore, that the columns form the corners of a number of
rectangular figures, which are either squares of 24 feet
each way, or consist of two or more such squares; and thus
the plan of the building may be said to be divided into its
elements. An exception to this arrangement, however,
occurs about the centre of the length, to meet a peculiar
feature of the case. A row of fine old trees, which the
public declared to be invaluable, here crosses the ground
occupied by the building, and, in order to enclose them, a
72-feet avenue, flanked by two 24-feet ones, is placed at
right angles to those in the direction of the length ; at the
same time, the roof of this transept is raised by being made
semicircular, so as to overtop the highest of the trees. The

crown of this. crystal arch is 108 feet from the floor
Whether viewed from within or from without, this transW
forms a beautiful feature in the building, and surpasses it*
type, the great Conservatory at Chatsworth, from its much
greater height. Four parallel lines of gallery, making a
total length of more than a mile and a half, 24 feet wide,
extend throughout the whole length of the building, ex'
cept where intercepted by the transept, round the ends of
which they are continued. They are reached by ten
double staircases, so placed between two lines of gallery as
to give access to each of them. The main lines are con-
nected, two and two, at intervals by cross galleries, no
communication, however, being formed across the main
avenue.

Having thus shown to what elements the plan of tht
building may be reduced, it will be sufficient, in order tc
form a general idea of the construction, to examine the
superstructure raised upon one such compartment of 24
feet square, which may be taken from the highest portion
of the building. Beginning, then, from the floor,—for we
will not now stop to examine the foundations and minute
details—there is a slender cast iron column at each angle oi
the square, rising to a height of nearly 20 feet above the
floor, and of the same diameter and form throughout; at
that height a separate length of shaft, rather more than
three feet long, is fixed on the lower portion, and is so
altered in its structure as to enable it to receive cast iron
girders in a horizontal direction; four girders, therefore,
connect the four columns, and in this way there are in the
whole building 2,150 such girders, supported on 3,300 cast
iron columns. These girders are of an open trellis pattern,
and form the support for the galleries, the floor of which,
therefore, is about 23 feet above the lower one ; this com-
pletes, as it were, the first story, which the two uppei
ones precisely resemble, excepting in height, as they are
only 20 instead of 23 feet high,'—also, that there is no
actual floor placed on the girders of the second story, and
in the third the girders support the roof. Such is the
structure of all the 24-feet avenues, either in one, two, or
three stories ; in those of greater width, the columns still
being only 24 feet apart in one direction, but 48 feet or 72
feet in the other, are connected, two-and-two, by cast iron
girders at the same levels as before ; but the remaining
girders, which are of wrought iron, are only introduced in
the upper story to support the roof, there being no occasion
for them below. These wrought iron girders, or roof-
trusses as they may be called, 372 in number, are similar
in general form to the cast iron ones, and of the same
depth—namely, three feet; it will be seen, therefore, that
the horizontal girders range at the same levels throughout
the whole building, which is a great advantage, in a con-
structional point of view, and at the same time produces a
very happy effect in the perspective. The open network
of the girders, and the slender lines of the supports, appear
rather as the slight framework of a temporary covering
than as forming portions of a permanent or solid structure,
a character which is very desirable where the building is
only the means to an end, and where the necessarily large
masses of the ordinary modes of construction would mate-
rially interfere with the effect of some of the objects
exhibited.

From what has been said, it will readily be understood
that the general form of the roof, with the exception of
that of the transept, must be flat, and in its construction
two essential requisites had to be provided for: first, for