Eye color: The myth. One of the oldest myths in human genetics is that having blue eyes is determined by a single gene, with the allele for blue eyes recessive to the allele for non-blue eyes (green, brown, or hazel).Many people who know nothing else about genetics think that two blue-eyed parents cannot have a brown-eyed child.ye color: The myth. One of the oldest myths in human genetics is that having blue eyes is determined by a single gene, with the allele for blue eyes recessive to the allele for non-blue eyes (green, brown, or hazel).
Micrometer Caliper. a measuring instrument whose conversion mechanism consists of a screw-nut micropair. Micrometer calipers are used to measure linear dimensions by the absolute contact method.omplete turns are read from a scale marked on the hub of the micrometer caliper, and fractions of a turn are read from a circular scale marked on the drum. A displacement of the screw of not more than 25 mm is optimum because of the difficulty of manufacturing a screw with an accurate pitch over a greater length.
A micrometer generally provides greater precision than a caliper, but is limited to a smaller range of lengths. For example, it would take a six-piece set of micrometers to cover the range of a 6 caliper. Parts of an Outside Micrometer. Proper Use and Care for a Micrometer.