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man who engages your attention and has a right to engage it. There were no preliminaries and there was no introduction. This was apparently his manner, and I submitted.
"I have here," he said, fixing me with his intense eyes, "the plans for a speedometer."
"Oh!" said I.
"You know what a speedometer is?" he asked suspiciously.
I said yes. I said it was a machine for measuring the speed of vehicles, and that it was compounded of two (or more) Greek words.
He nodded; he was pleased that I knew so much, and could therefore listen to his tale and understand it. He pulled his grey baggy trousers up over the knee, settled himself, sitting forward, and opened his document. He cleared his throat, still fixing me with those eyes of his, and said--
"Every speedometer up to now has depended upon the same principle as a Watt's governor; that is, there are two little balls attached to each by a limb to a central shaft: they rise and fall according to their speed of rotation, and this movement is indicated upon a dial."
I nodded.
He cleared his throat again. "Of course, that is unsatisfactory."
"Damnably!" said I, but this reply did not check him.
"It works tolerably well at high speeds; at low speeds it is useless; and then again there is a very rapid fluctuation, and the instrument is of only approximate precision."
"Not it!" said I to encourage him.
"There is one exception," he continued, "to this principle, and that is a speedometer which depends upon the introduction of resistance into a current generated by a small magneto. The faster the magneto turns the stronger the current generated, and the change is indicated upon a dial."
"Yes," said I sadly, "as in the former case so in this; the change of speed is indicated upon a dial." And I sighed.
"But this method also," he went on tenaciously, "has its defects."
"You may lay to that," I interrupted.
"It has the defect that at high speeds its readings are not quite correct, and at very low speeds still less so. Moreover, it is said that it slightly deteriorates with the passage of time."
"Now that," I broke in emphatically, "is a defect I have discovered in----"
But he put up his hand to stop me. "It slightly deteriorates, I say, with the passage of time." He paused a moment impressively. "No one has hitherto discovered any system which will accurately record the speed of a vehicle or of any rotary movement and register it at the lowest as at the highest speeds." He paused again for a still longer period in order to give still greater emphasis to what he had to say. He concluded in a new note of sober triumph: "I have solved the problem!"
I thought this was the end of him, and I got up and beamed a congratulation at him and asked if he would drink anything, but he only said, "Please sit down again and I will explain."
There is no way of combating this sort of thing, and so I sat down, and he went on:
"It is perfectly simple...." He passed his hand over his forehead. "It is so simple that one would say it must have been thought of before; but that is what is always said of a great invention.... Now I have here" (and he opened out his foolscap) "the full details. But I will not read them to you; I will summarize them briefly."
"Have you a plan or anything I could watch?" said I a little anxiously.
"No," he answered sharply, "I have not, but if you like I will draw a rough sketch as I go along upon the margin of your newspaper."
"Thank you," I said.
He drew the newspaper towards him and put it on his knee. He pulled out a pencil; he held the foolscap up before his eye, and he began to describe.
"The general principle upon which my speedometer reposes," he said solemnly, "is the coordination of the cylinder and the cone upon an angle which will have to be determined in practice, and will probably vary for different types. But it will never fall below 15 nor rise over 43."
"I should have thought----" I began, but he told me I could not yet have grasped it, and that he wished to be more explicit.
"On a king bolt," he said, occasionally consulting his notes, "runs a pivot in bevel which is kept in place by a small hair-spring, which spring fits loosely on the Conkling Shaft."
"Exactly," said I, "I see what is coming."
But he wouldn't let me off so easily.
"Yes, of course you are going to say that the whole will be keyed together, and that the T-pattern nuts on a movable shank will be my method of attachment to the fixed portion next to the cam? Eh? So it is, but"