“Without doubt he is mad, this Monsieur Power,” I said at last.  “You remember that he has just made two millions in a bear raid.  Doubtless it has turned his brain.  Name of a name!  He pretends to have taken flying lessons from an institute of correspondence, and I have promised him a biplane of one hundred horse power!  Georges, mon ami, you must yourself accompany it and give him counsel lest he break his neck!”

Not satisfied with this precaution, I myself flew the biplane over to Westchester on the morrow, and explained the controls to Monsieur Power in an extended passenger flight.  He was, it appeared, an amateur of the balloon, and accustomed to great heights.  When I handed the machine over to him, with the engine throttled down so that he might try rolling practice on the ground, he waited until he was out of our reach, whipped the motor into its full power, heaved himself into the air, and flew back the whole length of his grounds—­alighting gently as a falling leaf.

“It seems pretty simple,” he said, as he swung himself out of the nacelle.  “I do not think I need detain you, Monsieur Lacroix, if your assistant Georges will be good enough to consider himself my guest, and keep the motor running.”

It was in vain that I besought him to have patience.  He replied only that his time was limited, and that he had given the subject careful study in theory.

And with that assurance I had to depart, little content.  First, however, I warned him of one or two pitfalls—­as, for instance, that he must never stop his engine in an emergency, as one does instinctively in an auto, because the greater the danger the more need he would have of motive power to get him out of it.  Also, I told him not to fly above trees or water, where the currents would suck him downward, but to steer over the darkest patches of land, where the heat of the sun is absorbed, and the air in consequence rises.

In what state of emotion I was maintained by the letters of Georges during the ensuing fortnight, I will make you judge.

“A moi!” he writes to me in the first week.  “I am in the clutch of a madman!  Each morning I am awakened at six, that I may plunge with him in the lake of cold water attached to the mansion, he having first made la boxe noisily with a fist ball on the floor directly above.  To-day in his machine he has described figures of eight in the space of his grounds even, banking the planes at an inclination affreuse!”

Again he writes:  “I am now to accompany him on a cross-country raid.  Farewell to my wife and little one.  I will die like a Montmartrois for the honor of France!”

Finally an appeal—­urgent, pitiful, telegraphic: 

“Take me away, je t’en prie! This maniac wishes now to discuss the possibility of a somersault in the air.  I can no more—­Georges.”

Thereupon I replaced him with another mechanic, and he returned, appearing worn and noticeably thinner.