| 摘要 |
A bowling ball is made with a shell and a core of different compositions, with the core having a greater density than the shell so that the finished ball will have a predetermined weight; and the core also having a maximum dimension along an axis passing through the top of the ball where the finger holes are to be drilled, and a minimum rotational inertia around the same axis. The core is temporarily supported on a pin while the shell is cast around it, and the hole left by the pin is filled with a material of distinctive appearance to designate the top where finger holes should be drilled.
|
