At this point we have completely entered the world of historical fiction with no possibility of actual corroboration. This certainly explains the tale of a postponed publication to avoid so called living witnesses to denounce this tale. Worse the lack of actual science makes the exercise futile and powerfully suggests that it was all constructed of whole cloth.
Even the magic engine now possible was guessed at for decades.
At the same time though, we are using technology of the time and place to do thinks that are likely outside the actual reach of the engines of the time. Thus it really could not happen this way. There is also an eight hundred mile long tunnel without ample lighting to fly through to add to the problem. The author in fact shows a complete lack of scientific curiosity when it suits him and where the reader is most concerned...