Performing a Measurement

There are many ways to perform a measurement, but very few of them are correct. It is not enough to come armed with all the latest ‘gadgets’ and umpiring paraphernalia if you do not know the correct way to use them.

So how do you measure a point? Players often measure from the boule to the centre of the jack – this is incorrect. It may sometimes be employed for a “quick” measure, where there is a substantial difference in the distances being measured, but the distance required to be measured is the distance between the closest points of the boule and the jack.

Using a folding measure

As stated previously, the internationally recognised apparatus of choice for measuring short distances between the boule and the jack is the folding measure. With this apparatus, it is possible to measure with precision, distances from between 115 mm up to 1.1 metres.

As with all measuring equipment, it is imperative for the correct technique to be employed when using the folding measure.

1. After marking boules and jack as necessary and making mental estimation and note:

2. Open the folding measure to the approximate distance whilst holding away from the boule.

3. The measure should be kept in a right angle to allow for a firm grasp at the boule end to aid in stability.

4. Hold the measure just away from the boule and jack and push the slide out a fraction at a time until you are just (and only just) short of touching the jack.

5. Move the measure into position. The protruding “stub” should be placed against the boule with the smallest amount of light visible between the end of the measure (slide) and the jack.

6. Apply step 4 to the second boule. If there is no doubt as to which boule is closer, announce your decision to the players. If the difference cannot be judged without doubt, repeat steps 3 and 4, making more precise adjustments until you are able to make a decision.

Using the Folding Measure (as viewed from above)

Attention should be paid to maintaining the correct horizontal positioning on the boule.

Using a tape measure

It is considered by many people, that an accurate measurement is not possible with the use of a tape measure. It is however possible to be reasonably accurate using a tape, but care must be taken to use the correct technique.

1. The tip of the tape should be placed lightly on the closest part of the boule.

2. Extend the tape past the jack and as close to the top of the jack as possible without touching it.

3. Read the measurement and repeat for the other boule. (make as many measurements as you feel is necessary, to be certain of a correct decision).

Important

You should position yourself so that your line of sight is directly at 90^º to the edge of the distance being measured. This will avoid inaccurate measurements due to error of parallax as illustrated below.

Incorrect

Although the tip of the tape is positioned correctly on the boule, this exaggerated example shows how easily an inaccurate result can be obtained by the line of sight not being positioned directly over the jack. Coupled with the distance that the tape is being held over the jack, the error will magnify in accordance with an increased height of the tape.

Correct

In this example, the chance of 'parallax error' has been greatly reduced by the lowering of the tape and the positioning of the line of sight directly above the point being measured.

Using Callipers

Using Callipers, the same care should be observed as for the previous examples, to ensure the correct positioning on the boule and the jack. One point of the callipers should rest lightly on the boule and be lifted away slightly whilst adjusting, to avoid the possibility of disturbing the jack in the instance of the callipers ‘springing’ open.

Using Feeler Strips

There will be times where 2 or more boules are almost touching the jack, but with the slightest gap evident. On these occasions, it is necessary to use feeler strips (also known as feeler gauges) to measure the difference between. For this task, it is imperative that both the boules and the jack are marked. Then with steady hand, the strip is slipped alongside the boule and the jack before repeating for the other boule and comparing the difference between. If light is still visible between the strip and the boule, take the next thickness and remeasure until a decision can be ascertained.

Note: Great care must be taken when using this type of equipment.

Whatever your choice of equipment, correct technique is of utmost importance.