| 摘要 |
<p>The device comprises a clear plastics tube 1 having a smaller diameter blow tube 2 at one end and a ventilation hole 3 at the other and a table tennis ball 4 sealed therein. The tube is lined with a one inch wide felt 10 to provide frictional resistance to movement of the ball along the tube when the user blows through the blow tube. Markings may be provided on the side of the tube. In use, the tube is tilted either by resting one end on a pile of books etc. or by means of an adjustable stand 5.</p> |
