-----------------+------------------------------------------ SYMBOLS | ACCORDING TO | CONDITION OF OIL. TABLE III. | -----------------+-------+-------+-------+--------+--------- TIME. |15 MIN.|30 MIN.|1 HOUR.|6 HOURS.|ORDER OF | | | | |VISCOSITY -----------------+-------+-------+-------+--------+--------- E. K. W. w. | ... | ... | ... | ... | 2 W. F. N. w. | ... | ... | t-f. | t-f. | 4 D. C. S. w. | ... | ... | ... | ... | 2 D. C. S. ch. | ... | ... | ... | ... | 2 D. C. S. cl. | s-s. | s-s. | s-s. | s-s. | 6 W. C. w. | ... | ... | ... | ... | 2 B. & K. w. | ... | ... | ... | ... | 2 S. B. & Co. w. c.| ... | ... | ... | ... | 1 C. L. Co. w. | s-s. | s-s. | s-s. | s-s. | 5 C. L. Co. No. 1. | s-s. | s-s. | s-s. | s-s. | 7 Glyc. | ... | ... | ... | ... | 1 Alb. f. | ... | ... | ... | ... | 3 Sp. | s-s. | s-s. | s. | v-s. | 8 Ol. |v-t-f. | s-s. | s. | v-s. | 9 -----------------+-------+-------+-------+--------+-------- T. F. = Thickly fluid; or like honey. V. T. F. = Very thickly fluid; or like jelly. S. S. = Semi-solid; or like butter at 60° F. S. = Solid; or like butter at freezing point. V. S. = Very solid; or like paraffin wax. The figures in the last column denote the apparent relative viscosity, as ascertained by inverting the test tubes repeatedly. [Illustration: Fig. 15] Again, even if the oil were viscous enough in high temperatures to resist the tendency to be "squeezed" out of the bearings, the _rate_ of the timepiece would be seriously affected by the variation of solid and fluid friction--especially the latter--caused by a variable viscosity of the oil. When a watch, chronometer or clock 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; and it is obvious that if another oil be used, in which a greater or less variation of viscosity exists than in the oil with which such timepiece was lubricated prior to adjustment, the variation so produced will be more or less observable. It is, then, evidently necessary to be able to ascertain, with the greatest possible exactness, what change in this respect is produced in the various oils by a change of temperature. The means previously given (81-83) have their value; but when supplemented by a method for determining the particular property under consideration, the results obtained are exceedingly interesting and valuable. On account of the importance of this matter the author has made investigations in this direction, using a "viscosimeter" as shown at Fig. 15, and of which the following is a description: