The Boy Inventors’ Flying Ship was devoted to a detailed narrative of the boys’ long and unexpected cruise to the unexplored regions of the Upper Amazon.  The boys were shipwrecked and cast away without an apparent hope of rescue on a yacht belonging to a German scientist, the crew of which had mutinied.  The boys’ capture by a strange tribe and subsequent escape in their Flying Ship formed thrilling portions of this story, while Dick Donovan’s researches in natural history provided the boys with a lot of fun.

The volume immediately preceding this showed the boys coming to the rescue of a poor lad, a waif and orphan, who yet had a fortune in the plans and specifications of a new type of craft invented by his dead father who had lacked the capital to develop it.  Enemies strove desperately to secure the papers, and even went to the length of forging a will for the purpose, but partly through the agency of an odd German lad, Heiney Pumpernickel Dill, their schemes were frustrated and the invention was developed and set upon a working basis.  This book was called the Boy Inventors’ Hydroaeroplane, and dealt with some astonishing adventures and perils all of which the boys encountered with plucky spirits and resourceful minds.

For some weeks preceding the opening of the present book relating of the Boy Inventors, Mr. Chadwick had been closeted in his own private laboratory.  The boys had seen him only at rare intervals, and then he had appeared abstracted and preoccupied.  This, the boys knew, was a sure sign that he was at work on a new idea.

Sometimes the lights burned in his laboratory far into the night and in the morning he would appear at breakfast pale and silent.  The boys had indulged in much speculation as to what the new invention could be, but had arrived at no satisfactory conclusion when, two days after their experience with the eccentric professor, Mr. Chadwick summoned them to his private workshop.  The boys, who had been at work on the Wondership, the flying automobile with which they had met such surprising adventures in Brazil, obeyed the summons with alacrity.  It was delivered to them by Jupe, the negro factotum of the place.

“Massa Chadwick send me on de bustelbolorium,” explained Jupe, who had a vocabulary that was all his own, “for yo’ alls to come right away by his laburnumtory.”

“All right, Jupe, we’ll be right over,” said Jack, “just as soon as we’ve got some of this grease off our hands.”

The boys’ workshop was equipped with a washbasin and they soon made themselves presentable.  Then they hurried to Mr. Chadwick’s workshop.  They found him standing before a roughly-built table on which were ranged some odd-looking bits of apparatus.

There was a gasoline motor in one corner, geared to a generator—­or what appeared to be one—­from which feed wires led to a square metal box on the table.  Attached to this metal box was a sort of horn-shaped mouthpiece something like the transmitter of a telephone.  Hanging from its side was what looked like an enlarged telephone receiver.  Jack regarded his father questioningly.