"The _Snowbird_; eh?" he observed, looking sharply from one to the other of the five passengers of the huge flying machine. "_You_ are Amos Henderson, sir?" he pursued, nodding to the professor. "I believe I have heard your name before. Professor Henderson, whose scientific discoveries have made us all marvel of late?" "I am Professor Henderson," said the old gentleman, quietly. "And I can vouch for my companions. These boys, my adopted sons, have built this flying machine, and we are bound for Alaska." "Indeed! Then I fear I have caused you some slight trouble, not to say delay," said Mr. Ford. "We revenue agents are extremely anxious to overhaul and interview all aviators along the border. You understand?" "I believe that you have cause to suspect certain flying machines operating between the Canadian towns and Maine settlements," admitted Professor Henderson. "Quite right. And if our suspicions are based on fact, innocent flying men like yourselves may well beware of the fellows we are after. To be frank with you," pursued Mr. Ford, "a band of desperate smugglers are operating by aid of one or more aeroplanes. And piracy in the air may soon became as frequent--and as grave a peril to innocent aviators--as was ever piracy on the Spanish Main." "It seems impossible!" said the professor. "Who are these desperate criminals?" "A man named Bainbridge is at their head. He was originally a diamond dealer and finally was caught smuggling gems into the port of New York. He had to pay a huge fine and served a term at Atlanta for that crime and since then has sworn to be revenged upon the Government that punished him. "We learned of late that he was operating on the Mexican border--bringing into the States diamonds that had paid no duty--by aid of a flying machine. But the uprising in Chihuahua and along the border made his work exceedingly dangerous, and he was driven away from that part of the country. "Now we believe he has joined forces hereabout with ancient enemies of the Federal officers. At least, there is a strange aeroplane reported from both sides of the border, and some fine gems have appeared in the hands of certain suspected dealers in Maine, and as far south as Boston and Providence. "Bainbridge is known to be a desperate man. Look out for him, Professor. If you are hailed by another machine, better keep away from it," and the secret service agent laughed. "Had I been in your place I would not have halted on this occasion. You certainly can outsail any airship I have ever seen operated." Mr. Ford seemed quite satisfied that our friends were law-abiding and he ascended to his waiting craft in a few moments; and the _Snowbird_ started onward again through the starlight.