A caliper (British spelling also calliper, or in plurale tantum sense a pair of callipers) is a device used to measure the distance between two opposite sides of an object. A caliper can be as simple as a compass with inward or outward-facing points. The tips of the caliper are adjusted to fit across the points to be measured, the caliper is then removed and the distance read by measuring between the tips with a measuring tool, such as a ruler.It is used in many fields such as mechanical engineering, metalworking, woodworking, science and medicine.A plurale tantum sense of the word "calipers" coexists in natural usage with the regular noun sense of "caliper". That is, sometimes a caliper is treated cognitively like a pair of glasses or a pair of scissors, resulting in a phrase such as "hand me those calipers" or "those calipers are mine" in reference to one unit.Also existing colloquially but not in formal usage is referring to a vernier caliper as a "vernier" or a "pair of verniers". In imprecise colloquial usage, some speakers extend this even to dial calipers, although they involve no vernier scale.In machine-shop usage, the term "caliper" is often used in contradistinction to "micrometer", even though outside micrometers are technically a form of caliper. In this usage, "caliper" implies only the form factor of the vernier or dial caliper (or its digital counterpart).The earliest caliper of starrett has been found in the Greek Giglio wreck near the Italian coast. The ship find dates to the 6th century BC. The wooden piece already featured a fixed and a movable jaw.[1][2] Although rare finds, caliper remained in use by the Greeks and Romans.[2][3] A bronze caliper, dating from 9 AD, was used for minute measurements during the Chinese Xin dynasty. The caliper had an inscription stating that it was "made on a gui-you day at new moon of the first month of the first year of the Shijian guo period." The calipers included a "slot and pin" and "graduated in inches and and tenths of an inch."[4][5]The inside calipers are used to measure the internal size of an object.The upper caliper in the image (at the right) requires manual adjustment prior to fitting, fine setting of this caliper type is performed by tapping the caliper legs lightly on a handy surface until they will almost pass over the object. A light push against the resistance of the central pivot screw then spreads the legs to the correct dimension and provides the required, consistent feel that ensures a repeatable measurement.The lower caliper in the image has an adjusting screw that permits it to be carefully adjusted without removal of the tool from the workpiece.Outside calipers are used to measure the external size of an object.The same observations and technique apply to this type of caliper, as for the above inside caliper. With some understanding of their limitations and usage these instruments can provide a high degree of accuracy and repeatability. They are especially useful when measuring over very large distances, consider if the calipers are used to measure a large diameter pipe. A caliper does not have the depth capacity to straddle this large diameter while at the same time reach the outermost points of the pipe's diameter. For more info about us.