We have used the word “compile” advisedly. The writer has no new ideas or theories to put forth, for the reason that the mechanism we are considering has during the last six hundred years had its mathematics reduced to an exact science; its variable factors of material and mechanical movements developed according to the laws of geometry and trigonometry; its defects observed and pointed out; its performances checked and recorded. To gather these facts, illustrate and explain them, arrange them in their proper order, and point out their relative importance in the whole sum of what we call a clock, is therefore all that will be attempted. In doing this free use has been made of the observations of Saunier, Reid, Glasgow, Ferguson, Britten, Riefler and others in Europe and of Jerome, Playtner, Finn, Learned, Ferson, Howard and various other Americans. The work is therefore presented as a compilation, which it is hoped will be of service in the trade.
In thus studying the modern American clocks, we use the word American in the sense of ownership rather than origin, the clocks which come to the American workmen to-day have been made in Germany, France, England and America.
The German clocks are generally those of the Schwartzwald (or Black Forest) district, and differ from others in their structure, chiefly in the following particulars: The movement is supported by a horizontal seatboard in the upper portion of the case. The wooden trains of many of the older type instead of being supported by plates are held in position by pillars, and these pillars are held in position by top and bottom boards. In the better class of wooden clocks the pivot holes in the pillars are bushed with brass tubing, while the movement has a brass ’scape wheel, steel wire pivots and lantern pinions of wood, with steel trundles. In all these clocks the front pillars are friction-tight, and are the ones to be removed when taking down the trains. Both these and the modern Swartzwald brass movements use a sprocket wheel and chain for the weights and have exposed pendulums and weights.
The French clocks are of two classes, pendules and carriage clocks, and both are liable to develop more hidden crankiness and apparently causeless refusals to go than ever occurred to all the English, German and American clocks ever put together. There are many causes for this, and unless a man is very new at the business he can tell stories of perversity, that would make a timid apprentice want to quit. Yet the French clocks, when they do go, are excellent timekeepers, finely finished, and so artistically designed that they make their neighbors seem very clumsy by comparison. They are found in great variety, time, half-hour and quarter-hour strike, musical and repeating clocks being a few of the general varieties. The pendulums are very short, to accommodate themselves to the artistic needs of the cases, and nearly all have the snail strike instead of the count wheel. The carriage clocks have watch escapements of cylinder or lever form, and the escapement is frequently turned at right angle by means of bevel gears, or contrate wheel and pinion, and placed on top of the movement.
The English clocks found in America are generally of the “Hall” variety, having heavy, well finished movements, with seconds pendulum and frequently with calendar and chime movements. They, like the German, are generally fitted with weights instead of springs. There are a few English carriage clocks, fitted with springs and fuzees, though most of them, like the French, have springs fitted in going barrels.
The American clocks, with which the apprentice will naturally have most to do, may be roughly divided into time, time alarm, time strike, time strike alarm, time calendar and electric winding. The American factories generally each make about forty sizes and styles of movements, and case them in many hundreds of different ways, so that the workman will frequently find the same movement in a large number of clocks, and he will soon be able to determine from the characteristics of the movement what factory made the clock, and thus be able to at once turn to the proper catalogue if the name of the maker be erased, as frequently happens.
This comparative study of the practice of different factories will prove very interesting, as the movement comes to the student after a period of prolonged and generally severe use, which is calculated to bring out any existing defects in construction or workmanship; and having all makes of clocks constantly passing through his hands, each exhibiting a characteristic defect more frequently than any other, he is in a much better position to ascertain the merits and defects of each maker than he would be in any factory.
Having thus briefly outlined the kinds of machinery used in measuring time, we will now turn our attention to the examination of the theoretical and mechanical construction of the various parts.
The man who starts out to design and build a clock will find himself limited in three particulars: It must run a specified time; the arbor carrying the minute hand must turn once in each hour; the pendulum must be short enough to go in the case. Two of these particulars are changeable according to circumstances; the length of time run may be thirty hours, eight, thirty, sixty or ninety days. The pendulum may be anywhere from four inches to fourteen feet, and the shorter it is the faster it will go. The one definite point in the time train is that the minute hand must turn once in each hour. We build or alter our train from this point both ways, back through changeable intermediate wheels and pinions to the spring or weight forming the source of power, and forward from it through another changeable series of wheels and pinions to the pendulum. Now as the pendulum governs the rate of the clock we will commence with that and consider it independently.