Dating hemmi slide rule


One of Faber's most common, and most popular, slide rules. The Darmstadts' were always made of wood, like the early model 375 at the bottom of this page. Although superficially similar to such simpler models, this rule is far more advanced. It has most of the standard Faber innovations, like the five hairline cursor, multi-coloured scales, scale extensions, and self-documenting features. Note the unusual P, or Pythagorean, scale on the bottom of the front surface. Also unusual are the S and T scales on the hard cursor edge (see picture) and the L scale along with the inch ruler on the slanted edge. These scales are normally found on the reverse of the slider in most simple Rietz/Mannheim rules; in this case they are replaced by the 3 log-log scales (LL1, LL2, LL3). As standard on this type of rule, a table of standards and equivalents graces the back of the rule, which also has dual hairlines for reading the log-log scales. Except for the lack of a centimeter scale and the odd scale arrangement, I'd have to say this is one of the most useful simplex rule I've ever seen (for a comparison, check out the later-model "advanced Darmstadt" made by Hemmi ). Also standard is Faber's hard plastic green display case with clear top piece to show off the rule. A classic and elegant slide rule!

William Oughtred and others developed the slide rule in the 1600s. The slide rule is based on the work on logarithms by John Napier . Before electronic calculators were developed, slide rules were the tool used most often in science and engineering . The use of slide rules continued to grow through the 1950s and 1960s even as digital computing devices were gradually introduced; but around 1974 the pocket calculator made the slide rule largely obsolete and most suppliers left the business.

Hundreds of companies around the world were involved in the production of slide rules from the 18th to the 20th centuries. Click on one of the names below to see the objects in this collection that were associated with that firm.


Dating hemmi slide rule

Dating hemmi slide rule