the builder's art.

The Central Markets were to have been built of masonry, and the work
had even been begun, when, under the pressure of public opinion, the
architect, Mr. Baltard, was led to use iron. Evidently, the metal that
permits of covering vast spaces with the use of distant bearing points
that present a small surface in plan, and leaves between them wide
openings that the sun and air can enter in quantity, was the only
thing that was capable of giving the solution sought. So it has
been said, and rightly, that the Central Markets are, as regards the
distribution and rational use of materials, the most beautiful of the
structures of modern Paris. This system of construction at once met
with great success, and the old markets are everywhere gradually
disappearing, in order to give place to the new style of buildings.

Notwithstanding their number, the Parisian markets long ago became
insufficient, and wants increased with such rapidity that it became
impossible to supply them. The municipal administration was therefore
obliged, especially in populous quarters, to tolerate perambulating
peddlers, who carried their wares in hand carts. This system has the
drawback that it interferes considerably with travel, and especially
in streets where the latter is most active. Moreover, the merchants
and their goods are exposed to the inclemency of the weather. In
other places, where large spaces were utilizable, such as squares and
avenues, very light structures, that could be easily put together and
taken apart, were erected, and markets were opened in these once or
twice a week. This method presents serious advantages. Iron markets,
in fact, despite the immense progress that they mark, present
disadvantages that are inherent to all stationary structures. It
is necessary to erect them in populous centers, where land is
consequently of great value; and the structure itself is costly.

The result is that the prime cost is very great, and this forces the
city to charge the merchants high rents, and the consumer has to pay
for it. With movable markets, on the contrary, the city can utilize
large areas of unproductive ground, and find new resources, although
renting the stalls at a minimum price. The expense connected with the
structure itself is very small. In fact, the distinguishing character
of such structures is their portability--so that the same shed can be
used in any number of different places.

The principal expen