From: Research Laboratory of
A.G. Spalding & Bros. Inc,
Chicopee, Mass,
EXPLANATION SINGLE FLASH PICTURES OF CONTACT BETWEEN

CLUB AND BALL IN AN ORDINARY HIGH POWERED DRIVE

The accompanying series of single-flash pictures illustrates
the sequence of contact between club and ball in an ordinary high-
powered drive. The club was swung by a driving machine and propelled
a Spalding Dot ball approximately 250 yards carry-and-run. The in-
itial contact, the flattening, and the recoil of the ball from the
club-face, can be clearly seen,

Notice that the ball reaches substantially its maximum
flattening before its front edge moves at all. Notice, too, that as
the ball is compressed horizontally, its vertical diameter elongates,
and similarly, as it reacts from the compression, in leaving the club,
the horizontal diameter is stretched, and the vertical shortened.
These pictures provide valuable clues to the stresses to which the
interior of the ball is subjected.

From other similar photographs made especially for quanti-
tative measurement, the following interesting facts have been
determined:

For the contact pictured here:
The total duration of contact was 0.00040 secs.
Time of compression was 0.0002 .
" "decompression (restoration

of ball) was 0.0002 .
Backspin (Loft of club 12 degrees)

at rate of 4800 revs. per min.
Velocity of ball leaving club was 258 ft. per sec.

. " club before impact was 162 . " .

7 . " after impact was LZS " . ‘
Diameter of ball at rest (standard) 1.68 inches
Maximum diameter of ball was i.7c .

Minimum . a" " . 1.56 .

During contact face of club moved 0.355 .