CHAPTER XXII.
THE CONSTRUCTION AND REPAIR OF DIALS.
Probably no portion of the clock is more important than the dial and it is apparently for this reason that we find so little variation in the marking. The public refuses to accept anything in the way of ornamentation which interferes with legibility and about all that may be attempted is a little flat ornament in light colors which will not obscure the sight of the hands, as it is in reality the angle made by the two hands which is read instead of the figures. In proof of this may be cited the many advertising dials in which one letter takes the place of each character upon the dial and of the tower clocks in which the hours are indicated merely by blackened characters, being nothing less than an oblong blotch on the dial. Thousands of people will pass such a dial without ever noticing that the regular characters do not appear. Various attempts have been made to change the colors and the sizes and shapes of the characters but comparatively few are successful. A black dial with gold characters and hands is generally accepted, or a cream dial with black hands, but any further experiments are dangerous except in the cases of tower clocks, which may have gold hands on any light colored dial, or a glass dial. In all such cases legibility is the main factor sought and the bright metal is far plainer for hands and chapters than anything that may be substituted for them.
In tower clocks the rule is to have one foot of diameter of the dial for every ten feet of height. Thus a clock situated one hundred feet above the ground level should have a ten foot dial. On very large dials this rule is deviated from a little, but not much. All dials, except those of tower clocks, should be fastened to the movement, rather than to the case. This is particularly true where a seconds hand, with the small opening for the seconds hand sleeve, makes any twisting or warping of the case and consequent shifting of the dial liable to rub the dial against the sleeve at the seconds hand and thus interfere with the timekeeping.
The writer has in mind a case in which a large number of fine clocks were installed in a new brick and stone building. They were finely finished and no sooner had they been hung on the damp walls than the cases commenced to swell and twist. It was necessary three times to send a man to move the dials which had been attached to these clocks. As there were about thirty clocks it will be seen that this was expensive. After the walls had dried out the cases began to go back to the positions in which they were originally, as the moisture evaporated from the cases, and the dials had consequently to be moved through another series. All told it took something like a week’s work for one man to shift these dials half a dozen times during the first nine months of their installation. If these dials had been fastened on pillars on the movements, the shrinking and swelling of the cases would not have affected them.
It is for this reason that dials are invariably fastened on the movements of all high class clocks.
The characters on clock dials are still very largely Roman, the numerals being known as chapters. Attempts have been recently made to substitute Arabic figures and in such cases the Arabic figures remain upright throughout the series, while the chapters invariably point the foot of the Roman numeral toward the center of the dial. This makes the Roman numerals from IIII to VIII upside down, while in the Arabic numerals this inversion does not occur.
The proportions generally sanctioned by usage have been found, after measuring clock dials, all the way from two to eighteen inches, and may be given in the following terms: With a radius of 26 mm. the minute circle is 1½ mm. The margin between minute circles and chapters is 1 mm. The chapters are 8½ mm. The width of the thick stems of the letters are ¾ mm. The width of an X is 4 mm. and the slanting of X’s and V’s is twenty degrees from a radius of the dial. The letters should be proportioned as follows: The breadth of an I and a space should equal one-half the breadth of an X, that is, if the X is one-half inch broad, the I will be three-sixteenths inch broad and the space between letters one-sixteenth inch, thus making the I plus one space equal to one-quarter inch or half the breadth of an X. The V’s should be the same breadth as the X’s. After the letters have been laid off in pencil, outline them with a ruling pen and fill in with a small camel’s hair brush, using gloss black paint thinned to the proper consistency to work well in the ruling pen. Using the ruling pen to outline the letters gives sharp straight edges, which would be impossible with a brush in the hands of an inexperienced person.
For tower clocks the chapters and minutes together will take up one-third of the radius of the dial; the figures two-thirds of this, or two-ninths of the radius, and the minutes two-thirds of the remaining one-ninth of the radius, with every fifth minute more strongly marked than the rest.
We often hear stories concerning the IIII in place of IV. The story usually told is that Louis XIV of France was inspecting a clock made for him by a celebrated watchmaker of that day and remarked that the IV was an error. It should be IIII. There was no disputing the King and so the watchmaker took away the dial and had the IIII engraved in place of IV, and that it has thus remained in defiance of all tradition.
Mr. A. L. Gordon, of the Seth Thomas Clock Co., has the following to say concerning this story and thus furnishes the only plausible explanation we have ever seen for the continuance of this manifest error in the Roman numeral of the dial: