A muttered ejaculation burst from Vaughan Whittinghame's lips. This, then, was to be the fate of the precious submarine plans, for such the documents undoubtedly were.
The Mexican was on the point of letting the packet fall when the second Valderian touched him on the shoulder and said something. Durango shook his head. Again the Valderian spoke, seemingly in remonstrance. Just then a vivid flash of lightning threw the boundless expanse of sea into strong relief.
A tropical storm was brewing. Although there was practically no wind and the sea was as smooth as glass it was quite evident that the "Meteor" and her prey were heading towards the storm-centre. A glance at the barometer showed Dacres that, allowing for the difference in altitude when the instrument was last set, the mercury had dropped nearly three-quarters of an inch in two hours.
Suddenly the helmsman of the flying-boat put the vertical rudder hard over. Round spun the craft like a top, tilting to a dangerous angle as she did so. The unexpected movement took Durango by surprise, and unable to retain his balance he sprawled ignominiously upon the floor-boards. The precious plans slipped from his grasp.
As the fugitive boat swerved from her former course the quartermaster, running the port searchlight of the "Meteor," promptly swung the giant beam in the hope of following the elusive craft. The effort was in vain. The object of the chase darted out of the path of brilliant light and was instantly swallowed up in the darkness.
"After searchlights, there!" ordered Captain Whittinghame on the telephone. "Switch on and try to pick up the flying boat."
At the same time the "Meteor's" vertical rudders were put hard over, while the remaining propellers on the port side were set astern to assist in the more rapid manoeuvring of the airship.
Four searchlights swept the air in all directions. Yet although it seemed impossible that any object floating in space within the limits of the beams could escape detection there were no signs of the craft containing Durango and his two companions.
"Perhaps, sir, she crumpled her planes when she turned," suggested Dacres.
"Quite possible," assented Captain Whittinghame. "In that case she has a drop of nearly eight thousand feet before she hits the surface of the sea."