Thornton System Perry
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 Body-Upper Side Showing Cursor Indicator on 10 inch scale  Front  Well  Body-Lower Side showing cm scale  Back  Slider Back |
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Details |
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 Cursor Indicator at Top | |
 Front Left |
 Front Right |
 Well Left |
 Well Right |
 Bottom-Side Left |
 Bottom-Side Right |
 Back Left |
 Back Right |
 Slider Back Left |
 Slider Back Right |
Note This rule was invented by Prof. Perry and is called "System Perry." It has a pair of LogLog scales which refer A/B scales so that they cover modern equivalent of LL2 and LL3 (and their reciprocal scales) with a pair of scales. One mystery about this rule is that the cursor has a pointer to the ten inch scale on the upper side of the body. The rest of the scales being 25 centimeters long , what could be the possible use of this indicator?. |
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