There are many features covered that will enable him to develop in practice and to experiment in individual points of importance, without running up against mathematical deductions that halt and discourage further interest in the subject.
To understand the principles constitutes a large percentage of the qualifications required and to be able to execute the practical alterations and corrections required in different kinds of variations completes the general qualifications. It would hardly be sufficient, however, to conclude the work at this point without giving more definite examples for comparison, together with some indication as to the approximate time that may ordinarily be utilized in doing the work and also showing some instances of a possible choice of several alterations and why a particular alteration is advisable. For this reason the following examples will be found to have an important part in fulfilling the mission of this book.
In selecting these examples the fineness of results has not been the principal consideration. The deciding factor was the differences in variation and alterations, and the fact that they cover the widest field for general instruction that could be selected from hundreds of equally good rates among various models of watches which, with three exceptions, were put in order for railroad service.
The method of computing the variation from one position to any other is similar to that used in temperature adjusting as described in Chapter 3, No. 13. The watch should first be timed closely and then rated for twenty-four hours in each position. It should be wound before being started in each position but should be set only on the first day so that the time is never disturbed.
The first position to be rated is universally Dial Up, then in succession Dial Down, Pendant Up, Pendant Right and Pendant Left. The daily total number of seconds fast or slow should be entered in the first column of the rate card after each twenty-four hours run. This column then constitutes the progressive rate from which the actual variation between the different positions is ascertained.
The figure in the upper square is first carried out to the adjoining column at its full value and then the difference between this figure and that of the second square is entered in the second square of second column, and so on until the difference between each of the succeeding squares of first column is registered in the second column.
If the figure in a square of first column is greater than that in the preceding square the carried out figure would be entered in second column as + If the figure is less than the preceding square it would be carried out as-.
The total variation in positions is obtained from the figures entered in second column. If these figures are all entered as either plus or minus it is necessary to merely subtract the lesser figure from the greater. If, however, some figures are entered as plus and others as minus it will be necessary to add the greater figure of each of the two denominations.
[62.]Example No. 1, Three Positions.
Columbus, No. 358846, Open Face, 17 Jewels.