"Switch off, gas on," was the answer.

Tom made sure that the electrical switch was disconnected. If it
was left on, in "contact" as it is called, and the mechanician
turned the propeller blades, there might have been a sudden starting
of the engine that would have instantly kill the man. But with the
switch off there could be no ignition in the cylinders.

Slowly the man turned the big blades until each cylinder was sucked
full of the explosive mixture of gasoline and air.

"Contact!" he cried, and Tom threw over the switch.

Then, stepping once more up to the propeller, the man gave it a
pull, and quickly released it, jumping back out of harm's way.

With a throbbing roar the engine awoke to life and the propeller
spun around, a blur of indistinctness. The motor was working
sweetly. Toni throttled down, assured himself that everything was
working well, and then, with a wave of his hand toward Jack, began
to taxi across the field, to head up into the wind. All aeroplanes
are started this way--directly into the wind, to rise against it and
not with it. On and on he went and then he began to climb into the
air. With him climbed other birdmen who were to do patrol and
contact work with him, the latter being the term used when the
airship keeps in contact through signaling with infantry or artillery
forces on the ground, directing their efforts against the enemy.

Having seen Tom on his way, Jack turned to his own machine. As his