Museum of Obsolete Drafting Technology
Logarithms were invented in the 1600s and slide rules came along within a couple of decades. Since then slide rules have remained pretty much the same but became more accurate through better construction tolerances and also by clever means of lengthening the scale by wrapping them around a cylinder. Slide rules helped man reach the moon and were in use well into the 70s but disappeared rapidly with the advent of the digital calculator.
Circular slide rules got somewhat more scale length by wrapping the scales around a circle. Cylindrical instruments, got far greater length by wrapping the scale in a spiral around a cylinder.
Otis Carter Formby King (1876–1944) was a grocer and engineer in London who invented and produced a cylindrical slide rule with helical scales, primarily for business uses initially. The product was named Otis King's Patent Calculator, and was manufactured and sold by Carbic Ltd. in London from about 1922 to about 1972. With a log-scale decade length of 66 inches, the Otis King calculator should be about a full digit more accurate than a 6-inch pocket slide rule.
This Fuller Calculator made in England by Stanley is less than 18" long including the handle yet due to the spiral layout, its scale is 41 feet long. The slide rule consisted of three concentric cylinders. The outermost cylinder is 6" long and contains the 41-foot log scale. It can be pushed, pulled and rotated along the length of the middle cylinder. The middle cylinder is 12" long and is printed with information that varies based on the model.
There are three brass pointers or indexes. The appropriate one to use depends on the calculation.
To multiply X by Y, the outer cylinder is rotated/pushed to bring X to the fixed pointer. The inner cylinder is then rotated/pushed to bring A or B to 1 on the outer cylinder. The outer cylinder is then rotated/pushed to bring Y to A or B and the product could then be read at the fixed pointer F. This can be chained as needed.
The calculator is made of bakelite and brass and comes in a dovetailed mahogany box with a brass stand. This device was introduced in the 19th century, however the museum's copy was likely made in the early part of the 20th century.
George Fuller, professor of civil engineering at Queen's University in Belfast, Ireland, patented this instrument in 1878. The Stanley firm made about 14,000 Fuller's spiral slide rules over nearly one hundred years.
We love hybrid instruments like this tool which has a slide rule (for multiplication) on one side, and an Addiator (for addition and subtraction) on the other side.
Addiators came in a number of different flavors, and the AddFeet model adds and subtracts feet, inches, and fractions of inches. Try that on your generic calculator!
The buttons were made from M&Ms.
Compasses and dividers are probably the most used instruments in any draftsman's arsenal, along with scales and straight edges. Of course they come in a very wide variety of sizes and types of operation from small drop compasses for drawing small diameter circles such as rivets, or large beam compasses with extensions capable of drawing circles with radii up to 36" or more.
Two sets of bow compasses in Morocco cases with velvet interior and blue satin lining. By Stanley and "The Rathbone Technical Case No. 62".
Nickel silver Riefler beam compass in black leatherette case. Two extension arms can be added to draw arcs up to 24-inch radius. Case measures 3.25" x 13".
Nickel silver drop compass by Jules Bonin in Morocco case with ink and pencil attachments.
Unsigned pillar or folding compass in Morocco case.
Pillar Compass unfolded.
Pillar Compass unfolded with extension legs.
Pillar Compass can create two smaller compasses.
Parallel compasses are designed to that the legs of the compass always remain perpendicular to the drawing surface for greatest accuracy. This set comes with two extension legs allowing a circle up to 15" radius.
Without extension legs, this compass can draw circles up to 5" radius.
With extension legs, this compass can draw circles up to 15" radius.
Folding pocket compass with leather sheath.
Folding compass with leather sheath, unfolded.
We admire oddball inventions like this parallel compass with fixed bar which makes it very impractical to store.
Parallel compass with impractical fixed bar. Capable of circles up to 5" diameter.
Ott Pantograph by K&E in original case. Case is 5" x 25" covered in green cloth.
Patented by H. Ott, granted April 6, 1954.
Patent drawing for unusual cable release option, to disengage pencil.
Suspended pantograph from early Keuffel & Esser catalog. Note the prices. These were expensive!
These instruments are necessary for drawing both regular and irregular curves and come in a wide variety of shapes. Some are rigid, fixed curves of constant radius, made of acrylic, celluloid, or wood.
There are also adjustable curves capable of radii from 3-inches on up.
Set of Road Curves by Charles Bruning in oak box with clear plastic curves. Radii are marked at the sides of the box for each slot.
Box is divided into marked slots identified by radius.
Green plastic curves in this form were very popular in the drafting room circa 1960. Signed "Timesaver Curve No. 27".
Page from Keuffell & Esser Catalog
From antiquity, dividers have been used for marking off distances, taking measures off scales, dividing into equal parts, working with mathematical ratios, and for copying drawings on tablets, parchment, or vellum.
Unsigned brass proportional divider in morocco case line with blue satin lining.
Proportional Divider, used for enlarging or reducing drawings by direct measurement and for dividing circles into equal parts. As illustrated, it consists of two legs pointed at each end and hinged somewhere near the middle. The hinge joint is made adjustable to suit any ordinary ratio of reduction or enlarging which may be desired, specific ratio achieved. These instruments were often provided in the better quality sets up until the early 20th century.
3-legged dividers were used for transferring specific points on a map or drawing.
Manufacturers were always striving to come up with a better joint so that operation was adjustable, smooth and easy, yet firm to retain the setting.
What we would have given to have one of these when we were laying out stairs by hand! Ours is an uncommon 12-inch instrument with eleven points, signed Theo Alteneder & Sons. Stainless steel in cardboard box. Used for quickly and evenly dividing a line into ten equal segments.
Unusually long proportional divider with geared fulcrum on toothed rack. With instructions and original case which has ratios and numbers for dialing in specific ratios.
Six acrylic lettering templates, scriber, ink, and pen nibs in various sizes, in mahogany box.
Keuffel & Esser has pretty much had the lettering set market sewn up since the introduction of the Leroy Lettering Set. Most sets came in a compartmentalized mahogany box with slots for 10 or 15 templates of various sizes and typeface, pens in a wide range of widths, and room for scriber and ink.
The scriber holds a pen with ink reservoir. A pin on one end follows a groove in the selected lettering template, and a pin on the other end traces the letters in the template. Templates came in a wide range of sizes and typefaces.
This is a very early design with metal frame to hold plastic disc. The instrument is moved along a straight edge, by dragging with a pencil point inserted in a selected hole. By rotating the disc, lines of specific heights are lightly drawn on the paper to act as guidelines for lettering by hand or by a lettering device or system.
Original instructions included with the instrument in 1924.
Our Ames Lettering Guide was sent to Professor Mabel Spofford of Gloucester, MA. in 1924, along with instructions and a letter promoting the instrument. Ms. Spofford was a well reputed arts teacher.
This promotional letter was sent with a complimentary Ames Lettering Instrument in 1924 by Mr. O.A. Olson himself, to Professor Mable Spofford along with "some literature concerning it". This device is still wildly successful and used for drafting and still made by the original company in Ames, Iowa.
The Varigraph lettering device works very much on the same principal as the Leroy lettering system, using a scriber following a template and ink pen, but has the additional feature of being able to alter the height and width of the letters by manipulating the two knobs on the device which change the dimensions in the x and y directions. By changing just one of the knobs, letters can be made wider or thinner.
Steps 1 and 2...
Steps 3 through 6.
The importance of accurate scales was testified by the care with which draftsmen once kept their scales. Once housed in slotted boxes, scales gradually became used for uses other than merely scaling. An experienced drafter never used his or her scales to cut against or even tearing paper, and resisted loaning out his scales to others.
Box of Harling Scales with brass engraving plate.
Set of 5 boxwood scales and offsets in Mahagony box by Harling.
Set of 5 boxwood scales and offsets in Mahagony box by Harling.
Set of six boxwood and ivorine scales in oak box, by Dietzgen.
Made by Eyre & Spottiswood. Cardboard scales were often used by students and the less affluent draughtsmen since boxwood or ivory scales were quite expensive.
An opisometer, also called a curvimeter, meilograph, or map measurer, is an instrument for measuring the lengths of arbitrary curved lines.
Made by Lasico (Los Angeles Scientific Instrument Co.)
Made by T. Alteneder in velvet lined case.
Stainless steel, 36" long in original mahogany case.
Keuffel & Esser 5-inch Abney Level no. N5710 in original leather case and cardboard box, with instruction booklet.
Keuffel & Esser Abney Level for shooting spot elevations and gradients.
"Invented by a correspondence school student. May be carried in the pocket and at the same time answers every purpose of T-Square, Compass, Triangle, or Protractor." We have not been able to find one in the wild.
Boxwood scale with horse hair bristle brush.
Boxwood 45-degree triangle with horse hair bristle brush.
All signed Keuffel & Esser. Small lettering triangle at left. Miscellaneous curves and small 45-degree triangle on right.
Vintage camera lucida with two lenses in cloth covered case. F. Weber Co.
We do not have one of these in the Museum but would gladly accept donations! Keep an eye out...
Keuffel & Esser box for section liner.
Catalog page describing Both's Patent Section Liner and Scale Divider.
Keuffel & Esser box for section liner.
K&E 1161 Both's brass Section Liner and Scale Divider in oak box, with directions for setting and using.
Both's Patent Section Liner. Protractor graduated to degrees, with Vernier reading to five minutes.
Simplex Section liner, hardwood base, rod 15 inches, rule 7 inches. With cardboard box. "Will space lines up to about 1/4 inches and is very easy to handle".
Used for copying, and reducing and enlarging.
10" Melamine dinner plate with compass motif.
10" Melamine dinner plate with perspective motif.
10" Melamine dinner plate with dotting pen motif.
10" Melamine dinner plate with French curves motif.
"Koh-Liner Alpe" No. 3100. Made in Italy. Section Liner in tattered cardboard box.
"Koh-Liner Alpe" No. 3100. Made in Italy. Section Liner in tattered cardboard box.
Wood triangle with gizmo to allow small incremental movements for section lining.
Ivory handled ruling pens. Left-right:
Pricker, ruling pen, dotting pen with extra wheels in end cap, ruling pen, railroad pen, border pen, ruling pen.
These charts came with each set
Dotting pen by T. Alteneder in velvet lined case with two space wheels.
Set of three Marathon border pens by Keuffell & Esser. These broad bladed instruments held much more ink than standard ruling pens and were suitable for wider longer lines such as borders, without needing to be re-charged as often.
To fill his pen the draftsman presses the heel of his hand on the lever thereby raising the filling wire out of the ink bottle. He then touches the pen to the ink loaded wire. No need to unscrew and replace the cap each time ink is needed to charge the pen.
Fine presentation cases in boxes of burled walnut or cherry were often presented as prizes by some of the professional institutions or as retirement gifts for esteemed colleagues. I look at these sets, full of ink-encrusted tools, and wonder whose hands used them to design what bridges or buildings? Other sets are far more practical, some in metal cases so they would be portable and durable for field work, and some in small pocket sized leather-covered cases for general desk work. In almost all cases, while long term use is evident, it is also clear that these tools were respected and cared for with diligence.
Mahogany case with brass corners and escutcheons.
Made by Halden in mahogany case. Tray lifts out to reveal scales, protractor, and parallel rule.
Made by Halden in mahogany case. Tray lifts out to reveal scales, protractor, and parallel rule.
This was a pretty comprehensive set of instruments, and at a cost of $61 in 1889, it was quite valuable.
Example of a "Sandhurst Case" typically supplied to the military. This one made by Stanley has an upper tray with instruments and an ivory scale and protractor. The lower tier contains pens and a set of boxwood scales. Generously donated to the Museum by Karl Keesling.
Fine three-tiered magazine set in burled walnut case.
10" x 5" closed. Case re-bound in yellow buckram with burgundy silk ties. Case lined with blue velvet, and hand-marbled paper.
10" x 5" closed. Case re-bound in yellow buckram with burgundy silk ties. Case lined with blue velvet, and hand-marbled paper.
9.5" x 4.5" closed. Case re-bound in green buckram with silk velcro tie. Case lined with hideous green velvet, and garish marbled paper.
Riefler set. Germany. 11" x 6" closed. Gray leatherette case lined with red felt. These instruments have an unusual non-glare brushed-steel finish. These modern tools possess many thoughtful refinements like slide ejectors to remove broken pencil leads, and large diameter knurled screw knobs to make it easier to secure (and remove) leads and needles. Spare parts and screwdrivers are naturally included.
Small set by Wild Heerbrugg Switzerland. 7" x 4" closed. Black metal case with plastic insert. Very fine quality chrome plated instruments in an easily portable and durable metal case for field work.
High quality modern set from Switzerland. 11" x 6" closed. These very fine instruments have the highest quality polished stainless steel finish, and ultra smooth operation. Includes a fine drop compass and thick ruling pen. The balance and operation are peerless.
Pocket cases date to the 18th century and were made for the ship's captain and gentleman architect or mathematician. Pocket cases were made to be carried on the person and were sometimes referred to as 'gentlemen's travelling cases'. (This set is not in our collection, but is too pretty not to include).
Unsigned Pocket Case c. 1780. Green shagreen case with brass instruments, and ivory scale, sector, and parallel rule. This very fine pocket set was an upgrade to the more common cases covered in black sharkskin. (This set is not in our collection, but is too pretty not to include).
Well stocked set with the usual compasses but also a proportional divider, drop compass, and beam compass.
Walnut case with domed lid, 7.5" x 13".
Comprehensive set of instruments including dotting pens, drop compass and beam compass.
This deluxe Richter set was $75 in 1917 which translates into close to $1,500 today. It is very close to the set in the next exhibit below. We are huge fans of these Richter sets and are pleased to have two nice sets in the Museum.
Polished walnut box, 9.25" x 15.5". Flat lid.
Walnut case line with black velvet. This set is very close to that in the catalog page above and cost $75 in 1917. This set contained everything the professional drafter would need including a patented Richter ebony parallel rule/section liner. Also included are two dotting pens and a beam compass of typical Richter pattern.
This patented Richter parallel rule incorporated a clever ratchet to advance the rule very short but consistent distances for section lining and cross hatching.
Green leatherette hinged case with steel instruments. Case measures 5" x 10".
Steel instruments including large compass, horn center, and beam compass with square extension under flap in top lid.
Green leatherette hinged case with steel instruments. Case measures 5.5" x 10".
Quick set compass with locking cam, extension leg, horn center, and smaller bow compass.
Compass with extension leg is capable of drawing arcs and circles up to 12" radius. But wouldn't a beam compass work even better?
T-Square and Drawing Board with acrylic triangle, pencil and eraser.
30/60-, and 45-degree triangles.
Mahogany T-Square with ebony edges.
Harling 12" long Protracted Rolling Ruler with brass dividers, in mahogany box.
Protracted Rolling Ruler in mahogany case with brass dividers and round thing with brass needle..
Rolling ruler 18" long solid brass rolling ruler in green felt lined, black leatherette case.
Upper: 24" long solid brass rolling ruler by Klitsche & Co. in wood box.
Middle: 18" long solid brass rolling ruler by Keuffel & Esser in leatherette case.
Lower: 12" long rolling ruler by Harling & Co., in mahogany box.
Upper: 24" long solid brass rolling ruler by Klitsche & Co.
Middle: 18" long solid brass rolling ruler by Keuffel & Esser.
Lower: 12" long rolling ruler by Harling.
Mahogany triangles with ebony edges. 45- and 30/60-degree triangles.
This clever instruments is a parallel ruler and compass multi-purpose tool.
Three sizes of Dietzgen parallel rules: 18", 12" and 5". With original boxes.
K&E no. 1797. Ebony 18" Sigsbee's Patent Parallel Rule in original cardboard box. Nickel plated brass mountings. The bars are pivoted so the rules can be laid over (stepping) to cover any distance.
English Cased Set 4th quarter 19th century. Nickel silver and ivory instruments in 3-tiered magazine case. Unsigned, but likely by W.F. Stanley.
High quality cases such as this were sometimes presented as gifts or prizes, and could also be purchased fully equipped, empty, partially filled, for the owner to fill and add to over time by collecting instruments one at a time. A draftsman might add an ivory protractor or scale for instance, and ruling pens probably came and went.
Burled walnut case 14.25" x 6" x 4" with inlaid ornamental engraving plate on top and similar escutcheon for keyed lock. (Key is missing). Top lid is lined with padded blue velvet. Fitted velvet tray lifts out to reveal a second tray which lifts out to reveal a lower undivided compartment.
Contents: 21 instruments in nickel steel and ivory including:
- 6" compass with hinged legs.
- 5" compass with fixed legs and micro adjustment.
- extension bar
- five ivory handled ruling pens with square grips and ornamental turned finial ends; 3 with hinged nibs for cleaning.
- pencil and ink legs for compasses.
- two 3-inch compasses with turned finial handles.
- three small bow compasses with knurled handles.
- beam compass trammels with ink and pencil ends.
- Multi-tool with knife blade, screw driver, file, pin ends.
Contents:
- pencils, spare leads, cylindrical containers with spare leads and needles.
- unsigned rectangular ivory protractor with decorative end in compartment lined with blue velvet.
- six boxwood scales with beveled edges each side, marked with initials "W.A."
- four vulcanit scales signed Stanley
- seven cardboard scales signed "Measures Brothers Limited. 53b Southwark Street, London, S.E."
- six boxwood offset scales.
- one boxwood scale signed J. Halden & Co.
Undivided compartment containing:
- cardboard protractor, signed H.M Stationery Office, London..
- pair of wood Marquois scales with signature of "S. Greenhalgh".
- 12" wood bar with initials "W.A." for beam compass trammels.
- two acrylic triangles.
- brass protractor.
- wood handled ink pen with nib.
