NOMOGRAPH FOR USE IN MEASURING
SPEEDS BEYOND THE FLASHING
RATE OF THE TYPE 1531 STROBOTAC
The nomograph on the following page can be used to determine quickly
the fundamental speed of an object from two successive submultiple images.
To use the nomograph, find the point on the X scale corresponding to
the highest flashing rate at which a true stopped-motion image occurs.
Then find the point on the Y scale where the next lower true stopped image
occurs. Hold a straightedge so that it intersects the X and Y scales at the
points plotted. The straightedge should intersect the n scale at an integer.
Multiply the X scale value by this integer to determine the fundamental
Suppose that the first true stopped-motion image is obtained at 20,000
rpm, the next lower one at 15,000 rpm. A line drawn through 20 on the X
scale and 15 on the Y scale intersects the n scale at 3. Therefore the fun-
damental speed is 3 x 20,000 rpm, or 60,000 rpm.