Her dimensions allowed of her rising to the greatest height a balloon could attain; her impermeability enabled her to remain for an indefinite time in the atmosphere; her solidity would defy any dilation of gas or violence of wind or rain; her capacity gave her sufficient ascensional force to lift with all their accessories an electric engine that would communicate to her propellers a power superior to anything yet obtained.

The "Go-Ahead" was of elongated form, so as to facilitate her horizontal displacement.

Her car was a platform somewhat like that of the balloon used by Krebs and Renard; and it carried all the necessary outfit, instruments, cables, grapnels, guide-ropes, etc., and the piles and accumulators for the mechanical power.

The car had a screw in front, and a screw and rudder behind.
But probably the work done by the machines would be very much less than that done by the machines of the "Albatross." The "Go-Ahead" had been taken to the clearing in Fairmount Park, to the very spot where the aeronef had landed for a few hours.
Her ascensional power was due to the very lightest of gaseous bodies.
Ordinary lighting gas possesses an elevating force of about 700 grams for every cubic meter.

But hydrogen possesses an ascensional force estimated at 1,100 grams per cubic meter.