1 0 0 0 OA 細密読み取りダイアゴナル目盛の歴史
The Diagonal Scale has been employed for the precision reading of Electrical Measuring Instruments. Having searched for the source of precision readings in the measuring such as astrolabes, Tyco's quadrant or surveying instruments which employed nonious scales, diagonal scales and micrometer driven scales in Europe, the US and Japan from the fourteen century, the author found that Edward Weston in the US employed diagonal scales for the precision electrical meters in the last half of the nineteenth century. Those precision electrical instruments with diagonal scale have been used widely in the world and were manufactured by 1980s in Japan. The author studied the small errors caused by the scale configulation and how they were corrected. He also describes some examples of instruments which employed similar precision reading scales.