6.6 Non-Linear and Long-Scale Rules
Most people first recognize slide rules as linear devices, though circular logarithmic sliding scales were developed very early in the 1600s, including by Oughtred himself. And, in addition to scales in the shape of circles, slide rules were also created that contain other shaped curves, such as spirals on a circular platform, or even three-dimensional helical scales on the surfaces of cylinders. One major advantage of these “non-linear” designs is to provide a longer logarithmic scale to produce greater accuracy in reading and setting the numbers on the scale; or, consequently, a smaller device can be created with just as much or more accuracy as might be found on a longer “linear” rule with larger dimensions. Below we list all the items in the Collection whose scales are not straight linear scales. Also presented in our second list are those with longer than typical scale lengths for performing standard calculations (i.e., specialty slide rules are generally excluded from this list).
Two different lengths are indicated in the tables below. First, L0 is the length in inches of a single decade of the main scale (e.g., C, D) on the rule. The second parameter, Lx, is the length in inches of the slide rule’s maximum dimension. Note that the value of L0 for a typical linear slide rule is approximately 10 inches (25 cm). The first list below tabulates all slide rules in the collection that are not linear slide rules (i.e., circular, spiral, and helical slide rules). The second list has any standard slide rule with L0 greater than the standard 10 inches (25 cm).
Non-Linear Slide Rules
| Maker | Model | Year | Type | Mat | L0 | Lx | |
|---|---|---|---|---|---|---|---|
| Stanley London | Fuller’s Calculator Model No. 1 | 1909 | H | wd | 500.0 | 12.0 | |
| Gilson | Atlas |
|
1931 | S | Al | 468.0 | 8.0 |
| Otis King | Model L | 1949 | H | ss | 66.0 | 6.0 | |
| Otis King | Model K | 1965 | H | ss | 66.0 | 6.0 | |
| Felsenthal | AN 5837-1 | 1943 | C | pl | 60.0 | 8.0 | |
| Boykin | RotaRule Model 510 | 1965 | S | pl | 50.0 | 6.0 | |
| Sillcocks-Miller | M1 Slide Rule No. 547 | 1942 | C | pl | 31.0 | 12.0 | |
| Fowler | Long-Scale | 1943 | C | ss | 30.0 | 3.0 | |
| Palmer | Palmer’s Computing Scale | 1843 | C | pp | 27.0 | 11.0 | |
| Gilson | Binary | 1941 | C | Al | 26.0 | 9.0 | |
| Kahl Scientific | Culbertson Slide Rule | 1955 | C | pl | 24.0 | 8.0 | |
| Felsenthal | FAA-95 | 1950-1955 | C | pl | 16.0 | 8.0 | |
| C-Thru | PS-79 |
|
1970 | C | pl | 16.0 | 6.0 |
| C-Thru | S-96 |
|
1973 | C | pl | 15.0 | 6.0 |
| Gilson | Midget | 1919 | C | Al | 12.0 | 4.0 | |
| Gilson | Midget |
|
1940 | C | Al | 12.0 | 4.0 |
| General Luminescent Corp | Computer True Airspeed G-1 | 1942 | C | pl | 12.0 | 8.0 | |
| Felsenthal | D-4 | 1944 | C | pl | 12.0 | 4.0 | |
| Felsenthal | Logarithmic Calculator FF-6 | 1951 | C | pl | 12.0 | 5.0 | |
| Concise | 270 |
|
1955 | C | pl | 12.0 | 4.0 |
| Pickett | 101-C | 1962-1964 | C | Al | 12.0 | 4.0 | |
| Fearns Calculators | A13 |
|
1970 | C | pl | 12.0 | 5.0 |
| Palmer | Palmer’s Pocket Scale | 1845 | C | pp | 10.0 | 3.0 | |
| Felsenthal | Dial-A-Con | 1968 | C | pl | 9.0 | 7.0 | |
| Concise | 600ST | 1969 | C | pl | 8.0 | 3.0 | |
| Concise | 28 |
|
1970 | C | pl | 8.0 | 4.0 |
| Halden | Calculex |
|
1918 | C | ss | 6.3 | 2.5 |
| Simplified Flight Calculator Co. | Rhumb Line Distance and Course Computer | 1944 | C | pl | 6.0 | 6.0 | |
| Mims | Aver-O-Matic 121 | 1961-1962 | C | pl | 5.0 | 9.0 | |
| Graphic Calculator | Percentage Calculator | 1962 | C | pl | 5.0 | 6.0 | |
| MATSKU | KL-1 | 1969 | C | ss | 5.0 | 2.0 | |
| Gurley | Cox Stadia Computer | 1925-1949 | C | pl | 4.0 | 6.0 | |
| USA Mil | Nuclear Yield M4 |
|
1950 | C | pl | 4.0 | 5.0 |
| Felsenthal | Polhemus Celestial Computer | 1962-1963 | C | pl | 4.0 | 9.0 | |
| USA Mil | RADIAC ABC-M1 |
|
1950 | C | pl | 2.0 | 5.0 |
| Blundell Rules Limited | Radiac No. 1 | 1952-1956 | C | pl | 2.0 | 5.0 | |
| Concise | 380 |
|
1959-1966 | C | pl | 2.0 | 4.0 |
| USSR Military | Slide Rule RL | 1970 | C | pl | 2.0 | 7.0 |
Long-Scale Slide Rules
| Maker | Model | Year | Type | Mat | L0 | Lx | |
|---|---|---|---|---|---|---|---|
| Stanley London | Fuller’s Calculator Model No. 1 | 1909 | H | wd | 500.00 | 12 | |
| Gilson | Atlas |
|
1931 | S | Al | 468.00 | 8 |
| K&E | 4013 Thacher | 1907 | L | wd | 360.00 | 18 | |
| Otis King | Model L | 1949 | H | ss | 66.00 | 6 | |
| Otis King | Model K | 1965 | H | ss | 66.00 | 6 | |
| Boykin | RotaRule Model 510 | 1965 | S | pl | 50.00 | 6 | |
| Pickett | N1010-ES Trig Demonstration |
|
1958 | L | wd | 40.00 | 48 |
| Fowler | Long-Scale | 1943 | C | ss | 30.00 | 3 | |
| Palmer | Palmer’s Computing Scale | 1843 | C | pp | 27.00 | 11 | |
| Gilson | Binary | 1941 | C | Al | 26.00 | 9 | |
| Scofield | Engineer’s Slide Rule | 1901 | L | wd | 22.00 | 24 | |
| K&E | 4088-5 |
|
1920 | L | wd | 20.00 | 20 |
| K&E | 4092-5 | 1923 | L | wd | 20.00 | 20 | |
| Nestler | 24 |
|
1930 | L | wd | 20.00 | 20 |
| K&E | N4096 | 1935 | L | wd | 20.00 | 20 | |
| K&E | N4092-5 | 1936 | L | wd | 20.00 | 20 | |
| K&E | N4053-5 | 1937 | L | wd | 20.00 | 20 | |
| K&E | 4081-5 | 1956 | L | wd | 20.00 | 20 | |
| Aristo | 1067U | 1961 | L | pl | 20.00 | 20 | |
| K&E | 4083 |
|
1916 | L | wd | 16.00 | 16 |
| C-Thru | S-96 |
|
1973 | C | pl | 15.00 | 6 |
| noID | Gunter Rule |
|
1820 | L | wd | 12.00 | 24 |
| Kutz | Ullaging Rule | 1824-1827 | L | wd | 12.00 | 25 | |
| Dring and Fage | Inland Revenue Rule | 1883-1902 | L | wd | 12.00 | 24 | |
| Gilson | Midget | 1919 | C | Al | 12.00 | 4 | |
| Gilson | Midget |
|
1940 | C | Al | 12.00 | 4 |
| Felsenthal | Logarithmic Calculator FF-6 | 1951 | C | pl | 12.00 | 5 | |
| Concise | 270 |
|
1955 | C | pl | 12.00 | 4 |
| Pickett | 101-C | 1962-1964 | C | Al | 12.00 | 4 | |
| Fearns Calculators | A13 |
|
1970 | C | pl | 12.00 | 5 |
| Davies | Routledge Engineer |
|
1840 | L | wd | 11.00 | 12 |
| Stanley | No. 15 |
|
1858 | L | wd | 11.00 | 12 |
| E.S.A. London | Harrow Mark Reducer | 1898-1925 | L | wd | 11.00 | 36 | |
| Belcher Bros. | Engineer’s Rule | 1831-1843 | L | wd | 10.25 | 12 |
Note: The following slide rules are special cases in so far as scale length is concerned.
- The Fowler Long Scale Calculator is a segmented-scale rule with major scale made up of 6 individual circular scales totaling 30 inches in length.
- Thacher’s Calculating Instrument is also a segmented-scale rule, made up of 40 individual linear scales totaling 360 inches in length.
Distribution of Primary Scale Lengths for Entire Collection:
