PICKETT DECI-POINT SLIDE RULE ... |
This was one of Pickett & Eckel's first slide rules. This slide rule has what was at the time thought to be the great advantage of a technique to track the position of the decimal point during a calculation. Although the technique is very ingenious and deserves mention for this alone, the process was complicated and time consuming. Mind you, with a little bit of practice and perseverance, the process could become quite quick and mechanical. However, the scales on this slide rule were never repeated on later slide rules. In the following instructions for the use of this rule, screen shots will be used of the slide rule pictured. These images have been used after digitally removing the cursor from the photograph above and in some instances, may not be as accurate as the actual slide rule. Scales on the Deci-Point Slide Rule: 3√, 3√, 3√, L [ T, T, ST, S, CI ] C, D √, √ and these would be no surprise, especially to a 'Pickett'-user. The reverse side, however, is very different to any other Pickett slide rule as it did not carry what we know as the usual type of scales. Region, C', [ D', T', T', ST', S', DN ] RN-DZ, √, 3√ These scales' whole purpose were to enable the user to locate the decimal point for the calculation carried out on the front side of the slide rule. So in effect, the calculation was done twice;
The following links consider this slide rule and its operation in more detail. Explanation of the Scales of the Pickett Deci-Point Slide Rule Explanation of Digits and Zeros Example 3: Combined Operations Download the Patent Document for the Pickett Deci-Point Slide Rule (776 kB PDF)
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