A second scale, 26 centimeters in length, is on the front edge. The rule is in a cardboard case covered with black leather, which is in excellent condition. See MA.304722.02 for a later version of this rule, which mentions an 1899 patent and has a digit registering indicator introduced in 1905.
Underneath the slide is a third centimeter scale, numbered from 27 to 51. Reference: Dieter von Jezierski, Slide Rules: A Journey Through Three Centuries, trans. J.: Astragal Press, 2000), 54, 90; Trevor Catlow, "Suggestions for Dating pre-1920 Faber Castell Slide Rules," Journal of the Oughtred Society 18, no.
Background notes and more information on the limitations are given here.
Rod Lovett has created an on line searchable data base at
This is the later version of the 67/87R shown above and all the scales are now on the face. It has a vinyl wallet and instructions but was missing its cursor when photographed. Faber Castell 67/54R Darmstadt five inch plastic slide rule with Addiator on reverse. Faber Castell 67/22/R Business slide rule with Addiator on the reverse. Complete with green/transparent case and instructions. A ten inch closed frame, wood & celluloid slide rule with plastic cursor dated February 1969, with a green & clear plastic case. Faber Castell 375 ten inch System Rietz slide rule.
The Addiator (shown on the Addiator page) now has a negative window. It has a reversible slide with £,s,d scales on the reverse. Faber Castell 1/92 Log Log ten inch wood and celluloid slide rule., made in 1967. Closed frame, pear wood & celluloid, made in Bavaria in 1934. Faber Castell 378 ten inch, closed frame, electrical engineering slide rule, made in Bavaria. Closed frame, mahogany & celluloid, ten inch rule with reversible cursor for cm to inch conversions.
On the other hand relatively few rules of non-US manufacture appear for sale at the moment.
It is also possible that some slide rule manuals have been listed under slide rules.
Faber Castell 369 five inch, closed frame, mahogany & celluloid, Mannheim slide rule,made in Bavaria.
This one-sided, ten-inch wooden rule has a layer of yellowed white celluloid on the front side. Faber began manufacturing wooden slide rules in 1882 and added celluloid facings in 1887.
The analysis program does a search using the phrase "slide rule". These probably fall into two categories, those that no-one wants, even at a low price, and those for which too high a reserve has been fixed.
Some slide rules are sold using variants such as "slide-rule"; these are not checked but probably constitute only about 5% of all sales. It is clear that these auctions fall into a different category from those where a deal was arranged.
For more explanation of the table see the notes below. Another analysis I present is the hourly variation in prices.