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The role played by German watch and clock makers in the development of accurate time-measuring devices has not been given the credit deserved in modern histories devoted to this fascinating subject. The efforts of scientists, mathematicians, mechanics, and inventive geniuses all over the world have, in my humble opinion, been greater than were expended in any other human endeavor.
These tremendous efforts have been continuous. Beginning with the invention of the sun-dial somewhere in the Valley Of The Euphrates, so long ago that there is no history to record it, we come now to the atomic clock which is soon to be released, and which promises undreamed of accuracy.
As much effort and accomplishment in this never-ending climb to perfection in time-keeping has taken place in Germany, as in any other area of the world. On the basis of accomplishment alone, this area may rank well above all others.
Throughout this long history of prodigious effort, only a surprisingly few developments have contributed significantly to the progress of timekeeping devices. There have been thousands of inventions that promised much, but contributed little. Of all these the few inventions that profoundly effected the progress of the industry can be counted on the fingers of one hand. The first known mechanical clocks were weight-driven tower clocks; so inaccurate that, today, they would be considered useless. At the time, however, the leap from no time recording method at all to one of even extreme inaccuracy was an important one. Some improvement in the timekeeping abilities of these huge clocks took place over the early years.
The sad fact remained, nevertheless, that the weight-driven mechanism was only fit for large public clocks. It offered no possibilities at all for a smaller version for use in an individual home, nor, most of all, for a small time-keeping device that an individual could carry on his person for continuous reference.
This, then, was the story of timekeeping devices to about 1500 A.D. It appeared that the long history was about to come to an end because of the very limited possible application of the device as it was then constituted. The moderately successful clock of the year 1500 A.D. had a great past, but very little future. At this time, a young blacksmith in Germany came forward with an invention that practically obliterated the past and opened up an unlimited vista for the future.
The name Peter Henlein, who was born about 1480 and died in 1542, assumes a tremendous importance in this brief story of the development of time-keeping devices. This young man, working as a locksmith in Nurnberg, devised a means to make a long ribbon of steel which became the mainspring as it is known today.
This ribbon of steel, with one end affixed to a permanent anchor, and the other fastened to an arbor, could be tightly coiled or "wound up," thus storing power which could be released on a controlled basis to drive mechanical devices for a period of several hours. This made it possible, for the first time, to produce a smaller time-piece without the use of weights.
It opened up the possibility of a smaller clock that could be set up in any room of the house, and even be moved from one room to another; thus providing a means or method of making portable clocks. It also offered the possibility of making a time-piece small enough to be carried on the person; i.e., the watch.
In this connection, the following quotation, which has been widely used, is from the "COSMOGRAPHIA POMPONII MELAE," which was published in Nurnberg in 1511: "Every day finer things are being invented. Peter He1e, still a young man, has constructed a piece of work which excites the admiration of the most learned mathematicians. He shapes many-wheeled watches out of small bits of iron, which run without weights for forty hours, however they may be carried, in pocket of ehemisette."
From this quotation one might come to the conclusion that young Henlein was the first to make a time-piece known as a watch. Whether or not this be true, it is the invention and use of the flat coiled spring, opening wide the horizon of a great industry, that overshadows any of his minor accomplishments. Incidentally, there are several spellings of this name, but the most accepted is Henlein, which is the way it appears in the list of Nurnberg locksmiths.
One must not assume that the invention of the flat coiled spring changed the industry overnight. That is not the way of inventions, and this one is no exception. The world is slow to take to new ideas, particullarly ones with precedent-shattering implications. Furthermore, new inventions are usually crude, and far from perfect. Much refinement is necessary before they can be considered practical and efficient.
The introduction of the coiled spring as a means of power for clocks and watches gave unlimited scope to the potential uses of mechanical time-pieces. At the same :ime, its application presented immediate and almost insurmountable problems. The least important of these problems was that of breakage.
There were metallurgists to improve the formula, the making, and the tempering, so that breakage, while never entirely eliminated, was reduced to a bearable minimum. The matter of making the spring of sufficient length and strength to provide at least 24 hours of operation at one winding, was likewise a problem of refinement, adding nothing nor taking anything away from the basic idea.
The problem, which required the addition of something extraneous to the original invention, was the variation in power supplied by the spring when "wound up" or "run down," and the continuous variation between these two points. The crown wheel and verge type of escapement, the only one known and used at that time, was extremely sensitive to this variation in power.
With this type of escapelnent, the time-piece would gain at an exorbitant rate when the spring was fully wound and lose time as the spring ran down. This escapement was reasonably satisfactory in a weight clock, because the pull of a weight is constant, but its performance in a spring-powered time-piece was most erratic.
The first device to counteract the variation in power of the coiled spring is known as a "stackfreed." The origin of the word "stackfreed" is unknown and its inventor is also unknown, which is unfortunate. It is said to be a German invention and this is almost certainly true.
A very fine illustration of the "stackfreed" can be seen as Fig. 4 on page 16 of Britten's "Old Clocks And Watches And Their Makers," 1956 edition. An illustration may also be found on page 125 of "Time And Timekeepers" by Willis I. Milham. It appears in many other publications on old time-pieces.
The stackfreed is a spring with a small wheel or roller which presses against a cam or snail mounted on a cogged wheel that has the space of two or three teeth left uncut as a stop against over-winding. The shape of the cam was designed to cause the spring bearing against it to slow its action when the mainspring was fully wound, and to increase its action when the mainspring was running down. This was to equalize the torque between the times of winding, i.e., to even up the variation in power of the coiled spring. The stackfreed was an awkward mechanical device which passed with the early years of the 17th century. It may be said here, in passing, that it is true enough the "stackfreed" was a poor expedient and did not survive long. Nevertheless, the dream of most every collector is to find an old time-piece equipped with this device. It has great importance and value.
The device which adequately and effectively solved the problem of variation in power of the mainspring is known as the "fusee." Britten says of this device: " . . the fusee was a perfect remedy and survives in use in marine chronometers at the present day."
The best illustration I have seen may be found as Fig. 5, on page 17 of Britten's "Old Clocks And Watches And Their Makers," 1956 edition. It will, of course, be found in many other books dealing with old timepieces.
The fusee was invented by Jacob Zech of Prague in 1525. The word fusee is said to come from the idea of a thread-wound spindle. It refers to the catgut-wound fusees used originally to work the mechanisms. The fusee acted as an equalizer for spring-driven clocks.
When the spring was fully wound, the clock ran fast. As the clock spring ran down, the clock ran slow. To even up the clock's running, one end of a catgut was fastened to the large end of a conical-shaped grooved arbor or fusee. The other end of this catgut was fastened to the barrel that housed the mainspring, and about this barrel the catgut was wound.
Attached to the fusee a system of ratchet (angular toothed wheel), pawl, winding square, and hinged lever, wound the gut from the spring barrel onto the fusee, tightening the mainspring. As the end of the gut approached it tripped the hinged lever which reversed the gut and the compressed mainspring in the barrel pulled the catgut back onto the spring barrel, from the thin end of the fusee first, and from the broad end of the fusee later to balance the running down of the mainspring, thus equalizing the torque. The little hinged lever prevented overwinding of the mainspring.
Further comments on the fusee and the tremendous part it has played in the development of accurate timemeasuring devices will be made in the second part of this article.
It should be said here that the illustrations appearing in connection with this article are added merely as a matter of interest and have no direct bearing on the text.