Heading just a trifle north of east, they ran almost full-out.  It was easy to note the difference in the behavior of the Sky-Bird since her helium tanks had been fully charged.  She sped along as she had in the very beginning of their journey--like a long bullet fired from some gigantic cannon.  How the engine did sing!  The wind rushed by them like a hurricane, and they had to shout in order to be heard when they had anything to say to each other.