On another day perhaps you might have chanced to knock at his door when some serious complication had vexed him--a day when the cogs and pulleys upon which he had depended for certain demonstration had become so tangled up in his busy brain that he had thoughts for nothing else. Then, had he pushed pack his green door to receive you, his greeting might have been as cordial and his welcome as hearty, but before long you would have found his eyes gazing into vacancy, or he would have stopped half-way in an answer to your question, his thoughts far away. Had you loved him you would then have closed the green door behind you and left him alone. Had you remained you would, perhaps, have seen him spring from his seat and pick up from his work-bench some unfinished fragment. This he would have plunged into the smouldering embers of his forge and, entirely forgetful of your presence, would have seized the handle of the bellows, his eyes intent on the blaze, his lips muttering broken sentences. At these moments, as he would peer into the curling smoke, one thin hand upraised, the long calico gown wrinkling about his spare body, the paper cap on his head, he would have looked like some alchemist of old, or weird necromancer weaving a mystic spell. Sometimes, as you watched his face, with the glow of the coals lighting up his earnest eyes, there would have flashed across his troubled features, as heat lightning illumines a cloud, some sudden brightness from within followed by a quick smile of triumph. The rebellious fragment had been mastered. For the hundredth time the great motor was a success! And yet, had this very pin or crank or cog, on which he had set such store, refused the next hour or day or week to do its work, no trace of his disappointment would have been found in his face or speech. His faith was always supreme; his belief in his ideals unshaken. If the pin or crank would not answer, the lever or pulley would. It was the "adjustment" that was at fault, not the principle. And so the dear old man would work on, week after week, only to abandon his results again, and with equal cheerfulness and enthusiasm to begin upon another appliance totally unlike any other he had tried before. "It was only a mile-stone," he would say; "every one that I pass brings me so much nearer the end."