“That the attempt has been made to use the IV for the fourth hour on clock dials, any one making a study of them may observe. The dials on the Big Ben clock in the tower of the Parliament buildings, London, which may be said to be the most celebrated clock in the world, have the IV mark, and the dial on the Herald building in New York City also has it.
“That the IIII mark has come to stay all must admit, and if so there must be a good and sufficient reason. Art writers tell us that pictures must have a balance in the placing and prominence of the several subjects. Most conventional forms are equally balanced about a center line or a central point. Of the latter class the well known trefoil is a common example.
“A clock or watch dial with Roman numerals has three points where the numerals are heavier, at the IIII, VIII and XII. Fortunately these heavier numerals come at points equally spaced about the center of the dial and about a center line perpendicular to the dial. Of these three heavy numerals the lighter of them comes at the top and it is especially necessary that the other two, which are placed at opposite points in relation to the center line, should be balanced as nearly as possible. As the VIII is the heavier and cannot be changed, the balancing figure must be made to correspond as nearly as possible, and if marked as IV, it will not do so nearly as effectively as if the usual IIII is used.”
It is comparatively an easy matter to make a metal dial either of zinc, copper or brass, by laying out the dial as indicated above with Roman chapters and numerals, after first varnishing the metal with asphaltum. This may be drawn upon with needle points which cut through the asphaltum and make a firmly defined line on the metal. It is best to lay out your dial in lead pencil and then take a metal straight edge and a needle point and trace through on the pencil marks. Mistakes may be painted out with asphaltum, so that the job becomes easy. After this has been done a comparatively dull graver may be used to cut or scrape away the asphaltum where the metal is to be etched and then the plate may be laid in a tray, a solution of chloride of iron poured on and rocking the tray will rapidly eat away the metal, forming sunken lines wherever the copper or brass is not protected by the asphaltum. This furnishes a rough surface on the etched portions, which enables the filling to stick much better than if it were smooth. In tracing the circles a pair of heavy, stiff, carpenters’ compasses will serve where the watchmaker has not a lathe large enough to swing the dial. In all such cases it is best to start with a prick-punched center, tracing the minute circles and the serifs of the chapters with the compasses and then do your further division and marking by lead pencil, followed with the needle and then by the acids. It should be done before the holes are bored for the minute and seconds centers, as you then have an exact center to mark from and can go back to it many times.
This will be necessary in dividing the minute or seconds circle by hand (without an index on the lathe), as one of the tests of true division consists in having all marks lined up with a straight edge placed across the center. Thus IX and III should be in line with the center; VI and XII; X and IIII; I and VII, etc. It will readily be seen that for such purposes of reference the center should not be punched too large.
If it is desirable to ornament the dial, the desired ornament may be drawn on in the plain surface through the asphaltum and etched at the same time as the chapters and degrees. Or chapters and ornament may be drawn, pierced with a saw, engraved, filed up and backed up with a plain plate of another color. Gold ornament and silver background looks well.
Practically all the clocks having seconds hands carry that hand in such a position as to partially obscure the XII, with the exception of watchmakers’ regulators, and these, if they have separate hour, minute and seconds circles, are made large enough to occupy the space between the center and the minute circle, placing the hour circle between the center and the thirtieth minute; the seconds between the center and the sixtieth minute. The reason for this is that in the watchmakers’ regulators the hours are almost a matter of indifference; minutes are seldom referred to; the real comparison in watch regulation comes on the seconds hand. For this reason the seconds hand is made as large as possible and the chapters being placed on the hour circle by themselves, the seconds circle may occupy almost the entire distance between the center of the dial and the minute circle. They are placed one above the other because in regulators the time train is nearly always a straight-line train, which brings the seconds arbor vertically over the center arbor, and consequently the centers of the dials must be placed on a vertical line.
When the engraving has been properly done on a flat dial it is desirable to fill it with black in order to make it legible. There are several methods by which this may be done. The most durable is to make a black enamel and if it is a valuable clock the movement is generally worth a fine dial. The following formula will furnish a good black enamel:
| Siliceous sand | 12 parts |
| Calcined borax | 20 parts |
| Glass of antimony | 4 parts |
| Saltpetre | 1 part |
| Chalk | 2 parts |
| Peroxide of Manganese | 5½ parts |
| Fine Saxony Cobalt | 2 parts |
The enamel is ground into coarse particles like sand, and the incised lines filled with it, after which the brass or copper plate is heated red hot to fuse the enamel. Two or three firings may be necessary to completely fill the lines; after filling they are stoned off level with the surface of the dial. Jeweler’s enamel may be purchased of material dealers and used for the dials.