This handy fan scale measure can be used for many types of measurement, including maps. Sold for over half a century, it is still produced today in almost unaltered form.

This month’s measure is the Aristo fan scale. Fan scale rulers are compact and convenient and can be slipped into a pocket or briefcase until required. The measure features carefully defined divisions, or scale increments, on each of the five blades. It is a simple to use measure, confined only by the scales included and the length of each rule. The fan-type ruler was used by an engineer, draughtsman (American spelling- draftsman) and in construction, to measure distances and transfer the measurements at a fixed ratio of length.

Some of the ratios on the five blades are especially suited to scale drawings and, by simple additional scaling, with maps, the front and second measuring blades especially. An architect would refer to a drawing for the precise scale (ratio) and unit of measurement being used. Blades vary in length, shortest at the front and progressively longer toward the back. Blades increase in length by 4mm: 169mm, 173mm, 177mm, 181mm, 185mm. From front (shortest) to back (longest), the ratios shown on the fan blades are:

• 1:125, 1:1250 / 1:75, 1:750
• 1:50 (2:1), 1:500 (1:5) / 1:40, 1:400
• 1:33⅓ / 1:30, 1:300
• 1:25, 1:250 (1:2.5) / 1:20 (5:1), 1:200
• 1:15, 1:150 / 1:10, 1:100

These are close to the paired ratios normally found on architect’s flat scale rulers used in the UK and other countries that use the metric system, though 1:25, 1:1250, 1:33⅓ and 2:1 scales are less commonly seen.

The five plastic blades swivel out from a common pivot at one end, this gives the instrument it’s common product name- Fächermaßstab, or fan scale. When closed, they fold into a leather holder, or case, stitched on two sides. Dimensions of this are 192mm x 28mm x 6mm. Each Aristo 1323 weighs 23g, complete with leather case. There is a curved cut-out on both sides of the leather slip case so that the plastic measuring blades can be gripped and pulled out.

Two examples of the Aristo 1323 Fächermaßstab/fan scale are shown here. The black-cased measure is the earlier example. It has a brass rivet pivot for the fan blades. The leather slip case is embossed with a company name and logo, presumably used by employees of the UK based manufacturing firm Torvale Fisher. The rear of the leather case is plain, with no markings.

The brown leather case has a steel pivot rivet and in common with the black leather cased version, the rear of the brown leather case also has no markings, however the front is embossed with the company’s brand name: ARISTO. Below this, and in smaller font, the country of manufacture: MADE IN GERMANY. This changed in later years after the manufacturing base moved to Austria.

While the leather cases are obviously different colours, the five rulers in each are almost identical with identical scales. They do use a different format for the maker’s name and country of origin, also, a different font is used for the scales. However the divisions on the measures differ in their production. Divisions on the black cased example are etched and infilled with black. A photochemical etching technique for use with plastics was introduced by the company in 1941. Both have their divisions shown against a white background. The black case example incorporates the more expensive to make production method for the blades while measurement graduations on the brown cased example are simply printed directly onto the plastic fans. This is a cheaper method of production, increments wear quicker from use and is pretty much typical of the general fall in quality of production exhibited by many fine instruments and products.

The brand name Aristo was created by the company Dennert & Pape. This company has a long history. Johann Christian Dennert (1829-1920) was an assistant (from 1855) to engineer Carl Plath, manufacturing surveying instruments in Hamburg, Germany, and in 1862, purchased the sole rights to the business from Plath. For financial assistance, Dennert turned to Martin Pape (1834-1884), who became a full partner and engaged with the business from 1863. The firm was then named Dennert & Pape, a factory for mathematical instruments, making rules and other drawing instruments, planimeters and theodolites. An important and highly regarded product was their range of slide rules. When Pape died in 1884, Dennert took on sole control of the company. His two sons entered the business in 1904, Richard Dennert (1865-1924) taking on commercial direction and finance, Jean Dennert (1869-1916) running the workshop and manufacture of instruments. When Jean died in 1916, Richard took on control of the company, with the help of his father. Following Richard’s death in 1924, Jean’s son Christian and Richard’s son Georg, took on the business as partners however differences in their approach to commercial direction meant that they split in 1931, each taking on different branches of the company. Georg remaining with the original manufacturing base. Georg decided to only work in the new type of plastics being developed, This was ‘Astalon’ , a mixed polymer plastic of polyvinyl chloride (pvc) and maleic acid ester, developed and produced in 1936 by Dynamit AG of Troisdorf, near Cologne.

Astalon proved to be remarkably tough, U.V. stable, flame retardant and impervious to moisture. Drawing on the name of this ‘new’ manufacturing product, the firm introduced the trademark name of Aristo’ in 1936 for slide rules and drafting instruments made from the new plastic and it became an integral part of the firm’s name in 1956. The final family owner of the company was Hans Dennert (1926-2000), who joined the firm in 1957 though he had already apprenticed there for some years. From 1961 and a move to manufacturing in one of the largest municipalities in Tyrol, the independent Austrian firm was titled: ARISTO-Instrumente Dennert KG, Wörgl, Tirol. Today, the brand name Aristo is held by two companies; in Hamburg by Aristo Graphic Systeme and in Wörgl by the company Geotec, the latter continuing to make Aristo branded drawing instruments and other products, including the Aristo 1323 fan scale.

The Aristo 1323 fan scale is still listed amongst their products, alongside the similar model 1322. Aristo 1324 was another similar design of fan scale with eight blades. The scales on the 1324 are 1:75, 1:50, 1:40, 1:33-1/3, 1:30, 1:25, 1:15, and 1:10. The National Museum of American History informs us that model 1324 was being advertised in Dennert & Pape/Aristo’s 1955 catalogue. The Aristo model 1324-3 was a three-sided ruler with similar scales. This measure would primarily be used to measure fairly short lengths. If used for drawing, because the edges of each ruler were not edged, the measure was more suited to using with lead pencils rather than technical pens.

The Aristo 1323 Fächermaßstab is a simple form of measure and quite different from the great majority that have appeared as map measure of the month. It would be difficult to use this measure for simple plotting of a route. However, for pure straight line distances on map plans and drawings, it could suffice. Links to other map measures can be found here.

Much of the firm’s history above was taken from the company history produced by Dennert & Pape Aristo-Werke on the occasion of their centenary in 1962.