| Gauge Mark |
Value |
Definition |
Comments |
| ρ or M |
1.019 X 103 |
|
mils to Radians conversion |
| Cu |
1.124 X 10-1 |
|
finding weight of Cu solid |
| s |
1.273 |
4/π |
Flying Fish rules; finding area of circle |
| C |
1.128 |
sqrt(4/π) |
used to calculate circle areas and cylinder volumes |
| m |
1.28 |
|
used in US Gallon and meter conversions |
| NP or dB |
1.151 |
Ln(10)/20 |
Neper/decibel conversions |
| '' or // or : |
1182 X 104 |
(60*(180/π))² |
used to find sines or tangents of small angles |
| N |
1.340 |
|
used in converting British HP to/from kW |
| DNM |
1.359 |
|
Power conversion between Imperial and Metric units |
| y |
1.4 |
|
used in yard conversions |
| Cu |
.1482 |
sqrt((.01722 X 4)/π) |
finding resistance of Copper wire |
| Cu or Cu1 |
.1493 |
sqrt((.0175 X 4)/π) |
finding resistance of Copper wire |
| Cu1 |
.1495 |
sqrt((0.01755 X 4)/π) |
finding resistance of Copper wire |
| ρg |
1.571 |
π/2 |
|
| F or f |
.1592 |
1/(2π) |
for solving electrical circuit problems |
| cm |
16 |
|
Used in cm/inch conversions |
| ' |
1.667 X 10-2 |
1 minute = 1°/60 |
converts minutes to radians |
|
1.732 |
√3 |
Used in solving 3-φ problems |
| Q or ρ or ρ0 or 1° |
1745 X 10-5 |
π/180 |
used to find sines or tangents of small angles |
| ρCu |
1.750 X 10-2 |
|
finding resistance of Copper wire |
| d |
1.772 |
sqrt(π) |
|
| Cu |
1.785 X 10-2 |
|
finding resistance of a Copper wire |
| v or ρ |
1.910 |
6/π |
finding volume of sphere |
| Al1 or Al |
.1922 |
sqrt((.029 X 4)/π) |
finding resistance of Aluminum wire |
| 2g |
19.62 |
|
Twice the gravitational constant |
| ' or / or · |
1970 X 10² |
60*(180/π)² |
used to find sines or tangents of small angles |
| R1 |
1.986 |
|
Molecular Gas Constant in CGS units |
| ρ'' or '' or S or R'' or Q'' |
2063 X 10² |
(180*60*60)/π |
used to find sines and tangents of small angles |
| c |
2.154 |
∛10 |
used for finding cube roots when rule has no K scale |
| V0 or VM or MV |
22.42 |
litrs/mol ideal gas |
ideal gas calculations |
| 1n or L or U or 1/M |
2.303 |
1/Log10e |
Used for converting between natural and common logs |
| kg |
245 |
|
Used in lb/kg conversions |
| f |
2.533 X 10-2 |
1/(4 X π)² |
Resonant frequency calculations |
| F or 1F |
26.8 |
|
Faraday Constant |
| γAl |
2.700 |
|
finding weight of Aluminum wire |
| e |
2.718 |
Euler number; a constant |
Base of Natural Logarithms |
| '' |
2.778 X 10-4 |
1 second = 1°/3600 |
converts seconds to radians |
| ℧ or V or 1/R |
28.70 |
|
finding the voltage drop in Copper wires |
| ρAl |
2.900 X 10-2 |
|
finding resistance of Aluminum wire |
| ' or 1/ρ' |
2.908 X 10-4 |
π/(180 X 60) |
finding sines of small amgles expressed in minutes |
| W |
3.027 x 10-3 |
|
finding wt. of Cu wire given dia. and length |
| V |
30.49 |
23.950 X 4/π |
finding voltage drop in Cu conductors |
| π |
3.142 |
Ratio of circumference to diameter of a circle |
|
| □ |
3.162 |
√10 |
|
| M |
.3183 |
reciprocal of π |
|
| gE or g |
32.19 |
|
Gravitational Constant |
| W |
3.318 X 105 |
sqrt((4 X 44 X 106)/(π X 3 X 555)) |
finding weight of Copper wire |
| ρ' or ' or m or R' or Q' |
3438 |
(180*60)/π |
used to find sines and tangents of small angles |
| Al |
35.0 |
|
finding the resistance of Aluminum wire |
| C1 or C' |
3.568 |
sqrt(40/π) |
used to calculate circle areas |
| K |
.3592 |
273/760 |
gas volume calculations |
| 1/e |
.3679 |
Reciprocal of e |
|
| Cu |
.3782 |
sqrt(4/(π X 8.9)) |
for weight calculations of round Copper wire |
| Cu2 |
.3784 |
sqrt(4/(π X 8.89)) |
for weight calculations of round Copper wire |
| 39.4 |
.3937 |
1/(2.54) |
used in in/cm conversions |
| J |
4.186 |
No. of Joules in a calorie, or Watts in a calorie/sec |
|
| V |
4.189 |
(4 X π)/3 |
finding volume of a sphere; usually on K scale |
| M |
4.27 X 10² |
427 Kg-M = 1 Kcal |
|
| M |
.4343 |
Log10e |
|
| √ |
4.429 |
sqrt(2g) or sqrt(2 X 9.81) |
used in hydraulic problems |
| N |
.4492 |
1.2505 x (273/760) |
ideal gas calculations |
| c2 |
4.642 |
∛100 |
used for finding cube roots when rule has no K scale |
| kW |
465 |
|
Coupled Mark for kilowatt conversions |
| '' or 1/ρ'' |
4.848 X 10-6 |
π/(180 X 60 X 60) |
finding sines of small angles expressed in seconds |
| XM |
.5235 |
|
for computing reduction to the meridian |
| V |
.5236 |
π/6 |
finding volume of a sphere |
| 2F |
53.58 |
2 X Faraday Constant |
|
| lbs |
54 |
|
Used in lb/avoirdupois conversions |
| R |
552.8 |
sqrt(40/π X 24000) |
finding resistance of Copper wire |
| Cu |
57.1 |
|
finding the resistance of Copper wire |
| Qo or ρ0 or ρ or R or r or U or Ro |
5.730 X 101 |
180/π |
used to find sines and tangents of small angles; to convert Degrees to Radians |
| 60° |
.5774 |
tan of 30° or 1/(sqrt(3)) |
used for 1/(sqrt(3)) or 3φ current calclations |
| R2 |
62.36 |
|
Molecular Gas Constant |
| in |
63 |
|
Used in in/cm conversions |
| PS |
632 |
|
Coupled mark for metric horsepower conversions |
| Q,, or ρ,, or ρ or ρ, or ρg |
6366 X 10² |
(200*100*100)/π |
used to find sines and tangents of small angles |
| Al2 |
.6880 |
sqrt(4/(π X 2.69)) |
weight calculations of round Aluminum wire |
| N |
.7136 |
sqrt((.4 X 4)/π) |
finding resistance in Nickelin wire |
| PS or MOT |
.7358 |
1 metric horsepower = .73575 kilowatt |
converting horsepower to kilowatts |
| M |
.738 |
|
Probably finding resistance in Manganin wire |
| E or e |
775 |
|
conveting Watts to HP |
| HP or W |
.7456 |
1 British horsepower = .7456 kilowatt |
converting horsepower to kilowatts |
| A or S |
.7854 |
π/4 |
calculates area of circle from diameter |
| K |
.798 |
|
Probably finding resistance in Constantan wire |
| 3F |
80.4 |
3 X Faraday Constant |
|
| R3 |
8.205 X 10-2 |
|
Molecular Gas Constant in ISO units |
| dB |
8.686 |
20/Ln(10) |
Neper/decibel conversion |
| γCu |
8.900 |
|
finding the weight of Copper wire |
| Y |
0.9144 |
# meters/yard |
for meters/yards conversion |
| gF |
9.81 |
|
Gravitational Constant |
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