he hoe, the bore, and to human manipulation. There is nothing
more difficult to pierce and to penetrate than the geological formation
upon which is superposed the marvellous historical formation called
Paris; as soon as work in any form whatsoever is begun and adventures
upon this stretch of alluvium, subterranean resistances abound. There
are liquid clays, springs, hard rocks, and those soft and deep quagmires
which special science calls moutardes.[59] The pick advances laboriously
through the calcareous layers alternating with very slender threads of
clay, and schistose beds in plates incrusted with oyster-shells, the
contemporaries of the pre-Adamite oceans. Sometimes a rivulet suddenly
bursts through a vault that has been begun, and inundates the laborers;
or a layer of marl is laid bare, and rolls down with the fury of a
cataract, breaking the stoutest supporting beams like glass. Quite
recently, at Villette, when it became necessary to pass the collecting
sewer under the Saint-Martin canal without interrupting navigation or
emptying the canal, a fissure appeared in the basin of the canal, water
suddenly became abundant in the subterranean tunnel, which was beyond
the power of the pumping engines; it was necessary to send a diver to
explore the fissure which had been made in the narrow entrance of the
grand basin, and it was not without great difficulty that it was stopped
up. Elsewhere near the Seine, and even at a considerable distance
from the river, as for instance, at Belleville, Grand-Rue and Lumiere
Passage, quicksands are encountered in which one sticks fast, and in
which a man sinks visibly. Add suffocation by miasmas, burial by slides,
and sudden crumbling of the earth. Add the typhus, with which the
workmen become slowly impregnated. In our own day, after having
excavated the gallery of Clichy, with a banquette to receive the
principal water-conduit of Ourcq, a piece of work which was executed in
a trench ten metres deep; after having, in the midst of land-slides, and
with the aid of excavations often putrid, and of shoring up, vaulted
the Bievre from the Boulevard de l'Hopital, as far as the Seine; after
having, in order to deliver Paris from the floods of Montmartre and in
order to provide an outlet for that river-like pool nine hectares in
extent, which crouched near the Barriere des Martyrs, after having, let
us state, constructed the line of sewers from the Barriere Blanche to
the road of Aubervillier