Slide Rules

Some random pictures of Slide Rules.

Sterling slide rule

    10 inch Sterling
Cheap plastic.
This was my very first slide rule. I bought it new and paid maybe $4 for it. When I used it in high school my answers were often wrong in the last digit. My teacher checked it to see if I was blind or something and found it very inaccurate. He showed me his and I was amazed at how well it worked compared to mine. I stuck it in a box soon after I got a real one. Found it again in 2000 while cleaning out the barn. Sterling
Large pictures:

K+E N4053-5S Mannheim Polyphase slide rule

    20 inch Keuffel & Esser
Patent number 1,934,232 was issued to Keuffel in November 1933
Celluloid scales on mahogany.
The '-5' in the model number refers to the 20 inch length and the 'S' means leather case.
K+E N4053-5
Large pictures:

Seven foot long classroom slide rule

    Pickett Model N803-ES Log Log.
This is a large slide rule that is made to hang on the wall of the classroom above the chalk board. The teacher sticks his finger in a hole and hauls the tongue back and forth while the students throw spit wads. 7 foot slide rule If he is not paying attention he can get his finger cut clean off when it hits the metal end. It is made of yellow painted plywood and measures 84 x 10.5 x 0.75 inches closed.
Price was $25 in 1960. Pickett supplied these instructional rules free to schools with a minimum purchase of 24 normal slide rules.
Large pictures:

'ES' in the Pickett model number stands for 'Eye Saver yellowgreen'.
'N' probably means 'New' or maybe 'Nylon'.


The mysterious mark at 7854     Some slide rules have an inconspicuous mark located at 7854. This is pi/4 or one quarter pi.
It is used to quickly find the area of a circle from it's diameter. The area of a circle A = pi r2; but in practice it is usually the diameter that is known. Normally you would go D / 2 x D / 2 x pi, or D x D / 4 x pi, but that is just too much like work.
This special mark enables you to just go D x D x 0.7854.
Better yet do the entire calculation in one motion: Set 1 on 'C' opposite diameter on 'D', and read the answer on 'A' opposite 7854 on 'B'.

Sterling 5 inch pocket slide rule

    Sterling No. 587. This is a very cheap plastic rule. Sterling 5 inch pocket slide rule
6 inches; white plastic.
The accuracy of this thing is pretty bad; you would be better off with a pencil and paper.
Big picture:

Concise pocket circular slide rule

    A small circular rule marked with Motorola advertising slogans. Has case and instruction booklet. Concise pocket circular slide rule
3.2 inches; white plastic.
This was a free advertising gimmick that my father got at a conference in about 1970 or so.
Big pictures:

Nuclear Bomb Effects Computer

Nuclear Bomb Effects Computer     Companion to the 1962 edition of the book 'The Effects of Nuclear Weapons'. Fits in pocket inside the back cover.
5.15 inches; thin clear plastic.
1962 price was $1.00.
Large pictures:

Pickett 14 U.S. military slide rule

    Ten inch Pickett U.S. military slide rule. The leather case is lined with plastic and is marked US in gold. Tucked inside is a plastic strip with trigonometric formulae that you were supposed to memorize.
Besides degrees the scales are graduated in artillery mils. The army likes mils because they make the math easy and that is important in combat. There are 6,400 mils in a circle. Each unit is small enough that fractions are not used. The tangent of 1 mil is 0.001 (actually 0.000981748); this is handy for range estimation. The sights on guns are all marked in mils and the crews have various instruments that are marked the same. Pickett 14
The front side of this rule is nothing special. The back side has the special scales that are used to solve long thin triangles by the law of sines. One corner is occupied by the gun. A few hundred yards away is another corner where you have an observer. The sharp corner is the target. You measure the short side in advance. The two long sides are in enemy territory and the enemy is not going to let you run out there and measure them. You can ask him but he is going to say 'no'. That is why you need this special slide rule.
On the top edge is a pair of special scales, one in degrees and the same thing in mils. They run from 30° to 90° and then wrap back to 150°. They are named 'opposite angle' and represent the sine of the angle. You set the hairline to the angle measured by your observer. On the top edge of the slide is another pair marked 'apex angle' that go from 2° to 30°. You set the angle at the target that you find by subtraction under the hairline. Last you look on the D scale for the length of the base and read the range on C and shout it to the gunner and cover your ears. D is 10 times C, and C and D have extra zeros on them so you know that the base is supposed to be in hundreds of yards and the range is in thousands of yards.
Close up pictures:

U.S. military fire table for 155mm Howitzer

    3½ x 18 inch
155mm Howitzer Made of some sort of Masonite material
This is not really a slide rule, it has no moving parts except for the cursor. It is just a lookup table.
Close up pictures:

Pickett N 1006-ES

    Six inch 'Pocket Pickett' with trig scales. The pocket case has a leather pull tab to quickly eject the rule. Pickett N 1006-ES
Close up pictures:

Pickett Rotating Slide Rule Display Stand

Physical description:

Listing of slide rules on Pickett Display Stand
10"N1O1O-ES Powertrig$12.95
10"N1O1OSL-ES Super Powertrig$14.95
5"N200-ES Trig$6.95
10"N902-ES Simplex Trig$5.95
10"N4-ES Vectorlog$29.95
5"N3P-ES Synchrolog$13.95
10"N3-ES Synchrolog$26.95
10"N5OO-ES Hi-Log$16.95
5"N600-ES Log/Log$10.95

Pickett Rotating Slide Rule Display Stand

Close up picture:

The pictures and text for the display stand above and the K+E 4096 below are from Alan Morris, Dr. Eng., P.E.
He also wrote a paper entitled "Slide Rule Accuracy vs. Precision". SlideRulePaper.doc. It is in Microsoft Word 8 format.

K+E N 4096

K+E N 4096 in open case Here is the best photo of the K+E N 4096 that I took, enhanced to show the scales are present, with the rule pictured as it was conventionally used. This rule is, in my opinion, the most handsome slide rule ever made by K+E , or, in fact, by any other slide rule manufacturer. This 20" rule was patently designed for finding proportions.
It cannot be termed a "Mannheim," for the scales of this N 4096 are:

There are no scales on the reverse of the slide; only the serial number of the rule is engraved on the reverse of the slide. Note the brass knob near the left end of the slide. Also note that the magnifying glass of the cursor is installed on the cursor. See how the top of the black leather-covered storage box folds back exactly flat, with no overbending of the hinges; the top works in this way because the top of the box is exactly of the same dimensions as the bottom of the box. Note the German silver hinges and latches.
Per Wayne Feely's (Oughtred Society) document, "Keuffel & Esser Slide Rules, 1887 - 1967," © W. E. Feely, 1992, 1995, rule N 4096 is listed as "Desk Slide Rule w/Metal Stand, Knob, 20 inches," and this model N 4096 with knob first appeared in the K&E Catalog #37 of 1928.
Close up pictures:

I am not an active slide rule collector and have little idea of current prices etc. but you can check out these links to Web sites where slide rules are bought and sold:

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Last Update: December 8, 2009