In placing limits of allowance for variation in various grades it is not intended that all watches of a particular grade will have the extreme variation. It is possible that an individual watch in the twenty-five seconds allowance class may have an even better rate than another watch that is in the six seconds class. It is also possible for a watch in either class to have a perfect rate, although these would be rather exceptional instances.
24. _Some Necessary Requirements for Learning Adjusting._
The adjustments to isochronism and positions are not permanent to the same extent that the temperature adjustment is, and they can be damaged or destroyed entirely by the average workman in making ordinary repairs unless he is familiar with the common principles governing their production and maintenance.
Experienced workmen who are familiar with these principles avoid unconsciously doing any damage and make practical repairs in a manner that will maintain or improve the original adjustment and time-keeping qualities of the watch.
To know and to make use of these principles does not make a "putterer" of the workman, in fact the consequence is just the reverse, because the training acquired tends to eliminate guess work and enables him to determine more readily as to just what the trouble may be, how to correct it, and as to just what degree of perfection is required in a particular instance.
Certain practical requirements are necessary in reaching this standard of workmanship and it would not be profitable to attempt to do adjusting unless one has first had a reasonable degree of training as a watchmaker or repairer, especially in such branches of the work as truing and poising balances; truing, leveling and centering hairsprings; matching the escapement; finishing pivots, and properly cleaning and assembling watches.
These mechanical requirements and experiences alone are not sufficient, however, and a certain amount of study must be consolidated with them in order to become proficient. This study should not deal so much with the problems of manufacture of the watch, or its various parts, as it does with the problems pertaining to the finished results that are to be obtained through refinement and intelligent assembly of these parts. The workman's willingness to indulge in such study is a very large asset among the requirements, and it only remains for him to obtain the proper class of instruction and then to conscientiously follow correct methods in his practice and to make personal experiments, conforming to the instruction, so that his confidence will become more enduring.