compelled even Mahomet to restrain his vengeance. This check revealed to
Mahomet the extent of the danger to which his naval force was exposed
should either the Genoese or Venetians send a powerful fleet to the
assistance of the emperor Constantine.

This naval discomfiture was also attended by some disasters on shore. The
monster cannon burst before it had produced any serious impression on the
walls. Its loss, however, was soon replaced; but the Ottoman army was
repulsed in a general attack. An immense tower of timber, mounted on many
wheels, and constructed on the model used in sieges from the time of the
ancient Greeks and Romans, was dragged up to the edge of the ditch. Under
its cover, workmen were incessantly employed throwing materials into the
ditch to enable the tower itself to approach the walls, while the fire of
several guns and the operations of a corps of miners ruined the opposite
tower of the city. The progress of the besiegers induced them to risk an
assault, in which they were repulsed, after a hard-fought struggle: and
during the following night John Justiniani made a great sortie, during
which his workmen cleared the ditch, and his soldiers filled the tower
with combustible materials and burned it to the ground. Its exterior,
having been protected by a triple covering of buffalo-hides, was found to
be impervious even to Greek fire.

In order to counteract the effect of these defeats, which had depressed
the courage of the Ottomans and raised the spirits of the Greeks, the
Sultan resolved to adopt measures for placing his fleet in security, and
facilitating the communication between the army before Constantinople and
the naval camp on the Bosporus. The Venetians had recently transported
a number of their galleys from the river Adige overland to the lake
of Garda. This exploit, which had been loudly celebrated at the time,
suggested to the Sultan the idea of transporting a number of vessels from