1957-58

LAWN TENNIS 559
Applications for such adjusted standards may be made by
any National Association to the International Lawn Tennis
Federation and if approved shall be adopted for such
localities.
A table of such adjusted standards shall be added to the
Appendix from time to time as they may be adopted.
(iv) In all tests for diameter a ring gauge shall be used, consisting
of a metal plate, preferably non-corrosive
,
of a uniform
thickness
,
of
J
of an inch
,
in which there are two circular
openings 2.575 inches and 2.675 inches
.
in diameter respec-
tively. The inner surface of the gauge shall have a convex
profile with a radius of 1 X16 of an inch. The ball shall not
drop through the smaller opening by its own weight and
shall drop through the larger opening by its own weight.
(v) In all tests for deformation conducted under Rule 3, the
machine designed by Percy Herbert Stevens and patented
in Great Britain under Patent No. 230250, together with
the subsequent additions and improvements thereto, shall
be employed, or such other machine which is approved by a
National Association and gives equivalent reading to the
Stevens machine.
(vi) Immediately before any ball is tested, it shall be dropped
four times from a height of zoo ins. on to a concrete base.
(vii) To ascertain the deformation of any ball, three readings
shall be taken, one each of three diameters at right angles to
one another, so chosen that initially neither platen of the
machine shall be in contact with any part of the cover seam.
The average of these three readings shall be the deformation
reading.
(viii) After the ball has been placed in position, the contact weight
applied, the beam brought to the pointer level, the pointers
set at zero, and the test weight placed on the beam, the
pressure shall then be applied to the ball by turning the
hand wheel at a uniform speed, and exactly five seconds
shall elapse from the instant the beam leaves its seat until it
is brought to the pointer level, whereupon the turning shall
cease and the reading shall be taken.
CASES AND DECISIONS
Approved by the International Lawn Tennis Federation
12th Yuly,
1950
Rule 4
Case
1—Does a player, attempting a stroke, lose the point if he
crosses an imaginary line in the extension of the net,
(a) before striking the ball,
(b) after striking the ball ?
Ji
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