The values of the symbols and gauge marks on the slide rule scales and on the cursors are as follows:
(Note: Do not be confused as some marks look similar, but can have different values).
Note: Not all gauge marks could be identified. Instead, where a mark is unknown, a numerical value is shown.
Symbol | Comment |
π = 3.14159 | |
π / 4 = 0.7854 | This is to aid in finding the area of a circle by the formula; A = π D2 /4 |
v = π/6 = 0.5236 | This mark is on K scale and is used for calculating volume of sphere where V = (π/6) D3; also v = 4π/3 = 4.189 is on K where V = (4π/3) r3. |
R or ρ0 or ρ = 180/π = 57.2958° | The degrees in one radian |
M = 1 / π = 0. 3183, or 100 / π = 31.83 | |
C or C' = 4/π = 1.273 | f = 1 / 2π = 0.15915 |
c or C = (√ 4/π) = 1.128 | |
C1 = (√ 40/π) = 3.568 | |
1° = 1.745 * 10-2 = π / 180 | Marks for small angle calculations are usually on ST and read on C. The sine of one minute is = 2.909 * 10-4 ; the sine of one second is = 4.848 * 10-6 |
' or ρ' or 9' or δ' or ζ' or Q' = minutes in a radian = 3437.74 = (180 x 60)/π | If the mark ' is = 1.970, it is = 206,265 * (180/π) / 60 = 1.97 * 105 ; where, 206,265 = (180 x 60 x 60) /π |
" or ρ" or 9" or δ" or ζ" or Q" = seconds in a radian = 206,265 = (180 x 60x 60)/π | If the mark " is = 1.182, it is = 206,265 * (180/π) = 1.182 * 107 ; where, 206,265 = (180 x 60 x 60) / π |
ρ" or δ2 or ζ2 or Q2 = seconds in a radian (French decimal system 400) = 636,620 = (200 x 100 x 100)/π | |
| KW or kW stands for Kilowatts. HP(*) stands for Horsepower in U.S. and Great Britain. HP(**) for Horsepower in Continental Europe. |
| HP(*) (value for this mark is = 1.341). Conversions are: Kilowatts (KW) times 1.341= HP(*); Ergs per Second times 1.341 times 10-10 = HP(*). |
| HP(**) (value for this mark is = 1.358) for HP metric. |
| PS1 = factor is 1.33413 |
| PS2 = factor is 1.3599 (this is for HP metric) |