Neither Robur nor any of his companions had a suspicion Of the
catastrophe that threatened the "Albatross."

This was Uncle Prudent's plan. As he had said, he had stolen into the
magazine, and there had possessed himself of some powder and
cartridge like those used by Robur in Dahomey. Returning to his
cabin, he had carefully concealed the cartridge with which he had
resolved to blow up the "Albatross" in mid-air.

Phil Evans, screened by his companion, was now examining the infernal
machine, which was a metallic canister containing about two pounds of
dynamite, enough to shatter the aeronef to atoms. If the explosion
did not destroy her at once, it would do so in her fall. Nothing was
easier than to place this cartridge in a corner of the cabin, so that
it would blow in the deck and tear away the framework of the hull.

But to obtain the explosion it was necessary to adjust the
fulminating cap with which the cartridge was fitted. This was the
most delicate part of the operation, for the explosion would have to
be carefully timed, so as not to occur too soon or too late.

Uncle Prudent had carefully thought over the matter. His conclusions
were as follows. As soon as the fore propeller was repaired the
aeronef would resume her course to the north, and that done Robur and
his crew would probably come aft to put the other screw into order.
The presence of these people about the cabin might interfere with his
plans, and so he had resolved to make a slow match do duty as a
time-fuse.