The Calliper Measure
Recommended for distances of:
Minimum: 10 mm
Maximum: 200 mm
Callipers are ideal where the distance between the jack and bowls is fairly short. Callipers have two legs, fixed together at one end by a spring. You can adjust the distance between the tips of the legs and fix them apart using a screw-nut on a threaded rod.
You can use them to measure to a jack or bowl in the ditch but only if there is a direct line between the nearest points of the jack and bowl.
When using callipers:
- Make sure you follow the Common Procedures for conducting a measure described earlier.
- Kneel on the green and set the callipers at a distance that seems appropriate to the distance to be measured. Start with the callipers set at a distance that is less than the distance to be measured.
- Steady the hands by resting them on the green and move the callipers from top to bottom between the jack and bowl. As the bowl is the heavier object and less in danger of moving, initial contact should be made with the bowl and not the jack. (Note: The measure is made from the nearest points on the bowl and jack so the callipers must be held at an angle.)
- Remove the callipers from between the bowl and jack to make any adjustment to the setting.
- Open the callipers gradually and repeat step until the minimum of contact is made with both bowl and jack.
- Without altering the setting of the callipers, check the other bowls.
- It is important when using both Feeler gauges and Callipers that there are sufficient blades within the Feeler gauge to cover the distance of the Callipers when in their minimum measuring distance. This should be checked by all umpires within their kits.