Friction, Lubrication and the Lubricants in Horology - W. T. Lewis

Temp. 15.5° C. = 60° F. Inclination 6 degrees. Time 7 days.

SYMBOLS ACCORDING TO TABLE III.	DISTANCE IN CM. TRAVELED BY OIL AT THE END OF EACH DAY.							WIDTH OF TRACK.
DAYS.	1	2	3	4	5	6	7	WIDTH OF TRACK.
E. K. w.	16	18	Stat.	...	...	...	18	Medium.
W. F. N. w.	15	16.5	18	19	20	Stat.	20	"
W. C. w.	17.5	19	20	Stat.	...	...	20	Narrow.
B. & K. w.	12.5	15	17.5	20	Stat.	...	20	"
C. L. Co. w.	7.5	10	12.5	15	17.5	Stat.	17.5	Very wide.
C. L. Co. No. 1.	15	16.5	18	Stat.	...	...	18	Medium.
Glyc.	15	16.5	18	Stat.	...	...	18	"
Sp.	0	2.5	5	7.5	9	10	11	Narrow.
Ol.	5	6.5	7	Stat.	...	...	7	"

Table VII not only shows the relative viscosity of the various oils, but also their tendency to gum or dry (79.) The "width of the track" left by the oil is an indication of the cohesion (20) and adhesion (21) which exists, respectively, in the oil and between the oil and the glass. A narrow track denotes great cohesion and little adhesion; a wide track denotes great adhesion and little cohesion; while a medium track indicates that both properties are more nearly equal.

If an oil possess great adhesion and little cohesion it is more liable to resist the tendency to be squeezed out of bearings, but it is also more likely to spread.

Another test made in the manner just described (table VII) gave results as shown in table VIII:

TABLE VIII.

Relative Viscosity and Gumming of Oils.

Temp. 24° C. = 75° F. Inclination 7 degrees. Time 7.3 days.

SYMBOLS ACCORDING TO TABLE III.	DISTANCE IN CM. TRAVELED BY OIL AT THE END OF EACH DAY.
Days.	0.3	1.3	2.3	3.3	4.3	5.3	6.3	7.3
E. K. w.	14	23	26.5	28.5	29.5	31.5	32.5	33
W. F. N. w.	12.5	20	26.5	29	31	32.5	33.5	34
W. C. w.	19	24	26.5	28	29	30.5	32	33
B. & K. w.	14	17.5	25	27	29.5	31.5	33	33.5
S. B. & Co. w. c.	10	20	26	26.5	27	27.5	28	28.5
C. L. Co. w.	29	38	40.5	42.5	43	43.5	Stat.	43.5
C. L. Co. No. 1.	17.5	23	27	28	29	30	31	32
Glyc.	17.5	23	28	30	32	34	35	35.2
Alb. f.	15	20	29	33	35	37	38	38.5

The author once heard a watchmaker say to a customer, when the latter called for a clock which had been left for repairs, "I have cleaned your clock thoroughly; and, as you are a good customer, I made as good a job of it as I could. I even oiled it with watch oil." This watchmaker evidently thought he was right. It is hardly necessary to mention that a stock of oils of different viscosity should be kept on hand and intelligently used; the different bearings in any time keeping mechanism requiring oils of different viscosity. It is not to be supposed that the author means each bearing in a watch is to have a separate oil applied; but a distinction should be made between the light and heavy pressures.