This section is from the "Henley's Twentieth Century Formulas Recipes Processes" encyclopedia, by Norman W. Henley and others.
Enlarge, with the squarer (steel brooch for enlarging holes), the hole of the old setting, and adjust it, with hard rubbing, to the extremity of a stem of pierced brass wire. Take the stem in an American nippers, and set the ruby at the extremity (the setting may be driven back by using a flat burnishing tool, very gently). Then take off with a cleaving file the part of the stem where the ruby is set, and diminish it to the thickness desired, by filing on the finger, or on cork. These operations finished, a set stopper is obtained which now needs only to be solidly fixed at the suitable height, in the hole prepared.
Bent teeth are straightened by means of the screwdriver used as a lever against the root of the adjacent teeth, and bent pivots may be held in the jaws of the pliers and the pinion bent with the fingers in the direction and to the extent required. For such a purpose, pliers having the jaws lined with brass are used so that the pivot is not bruised, and the bending has to be done with great care.
Frequently, in consequence of the breaking of a spring, a tooth of a barrel is broken. Sometimes it may only be bent, in which case the blade of a penknife may be used with care. If 2 or 3 successive teeth are lacking, the best way is to change the barrel, but a single tooth may be easily renewed in this way: Drill a hole through the thickness of the tooth, taking care not to penetrate the drum; then fit in a piece of metal tightly and give it, as well as possible, the correct form of the tooth. To assure solidity, solder it; then clean and round the edges. Properly executed the repair will scarcely be noticed.
Sawdust is known to have been employed from time immemorial by watchmakers and goldsmiths for the purpose of drying rinsed articles. The process of drying can be accelerated four-fold if the sawdust is heated before use. This must, however, be done with great caution and constant stirring.
There are two kinds of false enamel for application, when cold, to damaged dials. The first, a mixture of white rosin and white lead, melts like sealing wax, which it closely resembles. It is advisable when about to apply it to gently heat the dial and the blade of a knife, and with the knife cut the piece of enamel of the requisite size and lay it on the dial. The new enamel must project somewhat above the old. When cold the surface is leveled by scraping, and a shining surface is at once produced by holding at a little distance from the flame of a spirit lamp. It is necessary to be very careful in conducting this operation, as the least excess of heat will burn the enamel and turn it yellow. It is, however, preferable to the following although more difficult to apply, as it is harder and does not become dirty so soon. The second false enamel contains white lead mixed with melted white wax. It is applied like cement, neatly filling up the space and afterwards rubbing with tissue paper to produce a shining surface. If rubbed with a knife blade or other steel implement its surface will be discolored.
Painting Roman characters on a clock dial is not such a difficult task as might at first be imagined. If one has a set of drawing instruments and properly proportions the letters, it is really simple. The letters should be proportioned as follows: The breadth of an "I" and a space should equal 1/2 the breadth of an "X," that is, if the "X" is 1/2 inch broad, the "I" will be 3/16 inch broad and the space between letters 1/16 inch, thus making the "I" plus one space equal to 1/4 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 it would be impossible to obtain with a brush in the hands of an inexperienced person.