| 摘要 |
PURPOSE: To make possible the measuring of the size of a subject and the distance thereto at a lower cost simply by holding the rule to view the distance therethrough by a method wherein the rule is set at a position at a specified distance ahead of an eye of a measuring person and the subject at a long distance is viewed through the rule to measure the size of the subject. CONSTITUTION: A rule 2 is set at a position at a distance X meter ranging 0.2-0.8 meter ahead of an eye 1 of a measuring person. The rule 2 is placed parallel with a subject 3 at a long distance and the subject is viewed through the rule to measure the size. The size of the subject 3 at the position of the rule 2 is put at A cm. The distance to the subject 3 from the eye 1 of the measuring person is put at Lm and the size of the subject at a distance is put at Hcm. Hence, an expression of H=A×L÷X is obtained. In other words, the ratio between the distance L to the subject 3 and the distance X of the rule ahead of the eye 1 is multiplied by a value A of the rule 2 and thus, the size H of the subject can be calculated simply.
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