chuckled the inspector. "He is dead right too."
"I wish to verify the stones as well as the setting," replied the expert.
"I guess in this case your stones are genuine enough. Stuart hadn't much chance to tamper with them. Nevertheless, it can do no harm to make sure," Corrigan said.
Opening a drawer Mr. Burton produced a powerful glass which he handed to Rhinehart who went to the light and carefully scanned the scintillating gems.
"Flawless and of the first water!" exclaimed he, after a tense pause.
"The setting hasn't been touched, so there is practically no danger of substitution."
"You mean we have actually got the ring back--diamonds and all?" put in Hollings, as if unable to make real the miracle.
"We have--thanks to Mr. Corrigan," was Mr. Burton's reply.
"Thanks to young Christopher, you mean, sir," smiled the chief protestingly.
"What can I do to thank you?" cried Hollings. "I said I would give anything I possessed if those diamonds could be reclaimed and I'm ready to live up to my promise."
"Pooh, pooh!" laughed Corrigan. "I've no wish for payment, man. To win out in this game is payment enough for me. Besides, the police are not allowed to accept money, you know. An officer of the law gets his satisfaction in clearing up a crime and locating the loot. Until he can do that his mind is never at peace. This day's stroke has enabled me to wipe two mysteries that have balked me off my slate and go to bed to-night with at least that many less on my mind."
He rose.
"Well, Chief, all I can say is that we are very grateful to you,"
declared Mr. Burton.
He would have said more had not the inspector raised his hand with a forbidding gesture.
"It's all right, sir. I'm fully as glad as you to see your property safely returned. If you have any thanks to bestow, pass them on to your son, for without him the missing diamonds might never have been located."
Then turning toward the boy he added:
"Should you want a job on the force, youngster, come down to headquarters. A lad who can win the hearts of criminals and coax them into voluntarily returning their ill-gotten gains would be an immense asset in our business."
Shaking hands all round and clapping Christopher affectionately on the shoulder, the chief went out.
"Better put that ring back in the show case, Hollings," concluded Mr.
Burton. "I don't need to caution you to keep an eye on it, I guess."
"You bet you don't!" was the fervent ejaculation. Then Hollings blushed to the roots of his hair at having thus addressed the great Mr. Burton.
But for once that worthy appeared to forget his dignity and, becoming human, he laughed like a boy of ten.
CHAPTER XII
CLOCK GIANTS
Gradually the excitement concerning the diamond robbery died away as do ripples in a pool and once more Christopher found himself settling down on the little wooden stool at McPhearson's elbow. The two had by this time become great friends, the boy preferring the companionship of the little Scotchman to that of any one else in the store. Perhaps this preference grew in a measure out of the fact that McPhearson appeared to like him and make more effort to entertain him than did the other clerks; perhaps also he had discovered that the clockmaker, when he did speak, was better worth listening to.
Be that as it may, he sallied into the repair department very glad to be there again.
"I feel as if I hadn't had a clock lesson for ages," observed he, as he sat down.
"Clock lesson? What do you mean?" The man with the swift-moving hands shot him a quick, puzzled glance.
"Oh, don't think I am here to steal your trade," retorted Christopher mischievously. "I only mean that so far as I am concerned the clock world stopped with Quare, Tompion, and Graham."
"Indeed it didn't," contradicted the Scotchman, instantly bristling.
"Though if it had, you would not need to be pitied for those makers would have bequeathed you some pretty fine products. And when you consider that Tompion, at least, began life as a blacksmith it is the more remarkable. Think what it meant to work out of such a crude, rough trade into one so delicate! Still, it was an age of marvels--a strange, fantastic, interesting era in which to have lived. Many members of the Clockmakers' Company were blacksmiths who had graduated into this higher calling and now boasted their own shops and apprentices. These latter men helped about under supervision, learning the trade and completing from eight to ten years of service before being taken in turn into the guild and permitted to make clocks. In the meantime they prepared simple parts of the work and made themselves useful in any direction they were able, even running errands or standing at the shop door and coaxing the passers-by to come in and purchase."
"Pretty primitive advertising," smiled Christopher.
"Advertising was primitive in those days," agreed McPhearson. "Sometimes when trade was dull the unfortunate apprentices were sent out to tour the streets and bring in customers. Or the present of a watch or clock would be made to the king or some nobleman of wealth and influence in the hope that such a gift would stimulate others to buy. No doubt even the celebrated Graham, in the days of his apprenticeship to Tompion, may have had some of these humble duties to perform. But if so they failed to dash his enthusiasm for his profession, for you see how well he profited by his teaching and what a master at clockmaking he finally became. He had always been an ingenious fellow interested in evolving mathematical instruments of all sorts."
"Were his clocks as good as Tompion's?" queried Christopher.
"As to that, the two were pretty well matched," was the answer. "Graham, however, concentrated most of his skill on watches while Tompion put the major part of his talent into long-case clocks which were unrivaled.
For, by this time, with the gradual development and improvement of clock machinery, it was possible to make grandfather, or long-case, clocks that kept excellent time. The defects of the old wheel escapement of the thirteenth, fourteenth, and fifteenth centuries were, as I told you, remedied in part by the invention of the fusee, a device for equalizing the movement. Then came the conversion of such clocks into pendulum clocks--no very difficult matter. One of the balls on the verge was removed, thereby making the verge longer and increasing the weight of the other ball. Then such clocks, together with those having a crown wheel escapement, went in turn out of vogue and the anchor escapement ushered in what is commonly known as the grandfather clock. It was in producing this particular type of timepiece that Tompion and Graham excelled. The pendulum was hung from a thin steel spring instead of being placed on an axis carrying pallets and could swing without friction."
"And whose scheme was that?"
"It is generally conceded that a Dutchman by the name of Fromanteel brought the modern pendulum idea into England. You will recall that early in clock history there were some pendulums of a very unsatisfactory nature in use--pendulums that were regulated by weights and dangled at the back or across the front of old brass clocks."
"I remember, yes."
"Well, it was that same pendulum principle carried to greater perfection and now scientifically applied which made the present grandfather, or long-case, clock possible. Certainly Fromanteel did a vast service to English clockmaking when he brought this solution of the pendulum problem to London, for with the anchor, or dead-beat escapement, combined with a long pendulum terminating in a heavy bob, the force of gravity caused such slight variation that the motion was practically harmonic and had only a very minor effect on the clock. For a long case, you see, has an exceedingly confined arc of oscillation because the swing of the pendulum is so limited. It is this length of pendulum together with its almost harmonic motion which results in the excellent time-keeping done by clocks of the "grandfather" class. The time a pendulum takes to vibrate always depends on its length--that is, the distance between the center of suspension and the center of gravity of the bob."
McPhearson paused to hold to the light a small brass pivot he was filing.
"Just here," continued he, "we stumble upon still another of the multiple tribulations of the clockmaker. If a big clock is expected to do any very fine work the latitude of the place in which it is to be put must be taken into consideration. For example, experiment has proved that the length of a pendulum vibrating seconds at London will not serve as accurately in other latitudes, because according to the laws of gravity the length of seconds increases in a specific ratio as we advance from the equator toward the poles. The clockmaker must, therefore, take care to regulate the length of his pendulum to correspond with this law."
"Great Scott! Why, I never dreamed there was so much to clockmaking!"
gasped the astonished Christopher.
"Oh, the making of a finely adjusted, close-running clock is far more of a science than a trade, laddie. It isn't just making a lot of wheels that will turn, hands that will point, or a mechanism that will tick--wonderful as all that is," asserted McPhearson.
"I don't believe most persons realize it isn't."
"Those who dip below the surface and are better informed know the truth; as for the others--we must not expect too much of a hurrying world, son.
Any branch of knowledge takes us very far if we follow it to the end.
Why, look at me! I have spent all my life with clocks and what do I know about them?"
"A great deal," was the prompt retort.
"Very little, my boy; very little indeed!" sighed the old man. "I couldn't make one. Nevertheless I have had great pleasure in hunting down what I have learned. It is an interesting subject and one that never seems to exhaust itself. For all the wonders of my trade are not yet told. When, for instance, they put the clock on the Metropolitan Life Insurance building here in New York an undreamed-of pinnacle in clock construction was reached. There was a time when the clock on the London Houses of Parliament was the last word in the art--a veritable triumph of the horologe. Not only was it the largest timepiece in the world, but it seemed then the most miraculous."