(1.) If some of the bearings need a small quantity of oil, being otherwise in such good condition--because of never having been used, in fact "new"--that it is unnecessary to take all the mechanism apart and clean it, it is very important that the operator know what kind, or variety, of lubricant has been previously used, in order not to "mix oils;" or, if a mixture is thus made, to make it intelligently. (85.) (2.) When the oil which has been applied in the factory has not performed its functions properly in any part of a time piece, it is necessary to know what particular variety of lubricant has been used in order to substitute an oil which possesses the properties lacked by the oil previously used. (61.) (3.) In a watch which has been so adjusted as to keep a maximum even rate, the oil is one of the factors of the variation which has been overcome. It is necessary, then, on putting the watch in order, to employ a lubricant which possesses the same variation of viscosity as the oil which was used during adjustment. (84.) Some other interesting facts are shown in table XII, as well as the foregoing. The queries were as follows:-- QUESTIONS ASKED. 1. What oil do you use? 2. What oils have you tried? 3. What has been your experience with mixed oils? 4. Do you use the same grade of oil on all parts of your ----? 5. If not, what is your practice? 6. What amount of oil do you use annually? The answers are given in Table XII. ~87. Impurities in Oils~ and all foreign matter exert a very injurious effect. The method of sealing the bottles with sealing wax or gum labels should be avoided; the former, as the wax is brittle and liable to break in very fine pieces which lodge around the cork from whence they get into the oil; and the latter because the gum with which it is caused to adhere remains on the bottle, only to be absorbed by the oil. Paraffin wax makes a very good sealing material, as it is not brittle, and keeps the oil protected from the air. An extra long cork should accompany each bottle. TABLE XII.--ANSWERS TO QUESTIONS.