Distance of the piston from the end of its stroke when the steam is cut off, in parts of the length of its stroke.

½

5/12

1/3

7/24

1/4

5/24

1/6

1/8

1/12

1/24

Lap in parts of the stroke....

.354

.323

.286

•27

•25

•228

•204

•177

144

102

Illustration

Take the elements of the preceding case.

Under 1/6 is .204, and .204 X 16 = 3.264 inches lap.

When The Valve Is To Have Lead

Subtract half the proposed lead from the lap ascertained by the table, and the remainder will be the proper lap to give to the valve.

If, therefore, as in the last case, the valve was to have 2 inches lead, then 2 / 2 - 3.264 = 2.264 inches.

Portion of the Stroke of a Piston at which the Exhausting Port is closed and opened.