A.W. Faber 357 & 367 w/Decimal Tracker

The Model 357 was manufactured in Germany from 1899 until 1907. The rule's body and slider were made of German boxwood, covered with white celluloid, but there were models manufactured bare-wood. The scales are of the railroad type, printed on the bare-wood or on the celluloid . The glass cursor had a metallic frame extended with a nice decimal keeper arrow. This basic Mannheim type rule had on the front face the scales: Upper edge 27cm ruler // A [ B, C] D || Lower edge 29cm ruler, and scales [ S, L, T ] on the slider's back. It has also an inner scale in centimeters, that makes the 357 model an extensible ruler, up to 55 cm long. On the slide rule's back there is a robust Unit Conversion and Constants Table.

Determine the exact year these old Faber-Castell models were manufactured is not an easy task, but I assume that this piece was manufactured in 1905 or before, according with the engraving made by the original owner on the back of the rule. This is the oldest slide rule in my collection; it is in reasonable fair workable conditions for a 100+ years old collectible, but the A scale is faded between values 1 - 1.7; scale D is is cracked between values 1 - 1..3, and the unit conversion table at the rules back is faded at the ends.

Another curiosity of this rule is that came to me with the A-scale upside-down! I guess the celluloid got loss and it was glued wrong. Very patiently and carefully I scrapped out this strip and glued correctly. See pictures below to see this rule "original" conditions:

The Model 367 is identical to model 357, but the original inches-centimeters scales on the rule's edges are now engraved on the white celluloid covering these edges. This rule was manufactured in Germany from 1909 until 1920. As their 357 predecessor, the 367's body and slider were made of German boxwood, covered with white celluloid, The scales are also of the railroad type, printed on the celluloid . The glass cursor, a little bit more compact on the upper edge, because a small re-design of the rule's body, also has the nice decimal keeper arrow. This basic Mannheim type rule had on the front face the scales: Upper edge 27cm ruler // A [ B, C] D || Lower edge 29cm ruler, and scales [ S, L, T ] on the slider's back. It has also an inner scale in centimeters, that makes this model an extensible ruler, up to 55 cm long. On the slide rule's back, it is the same Unit Conversion and Constants Table as on the 357.

It is not possible to determine the exact manufacturing year of this rule, the only certainty is that it was manufactured before 1920. This is one of the oldest slide rules in my collection; it is in workable conditions for a 100+ years old collectible, all scales are perfectly readable as well as the Units Conversion Table on the rule's back side:

Here are the models 357 and 367 side to side:

I have no found a user manual for this rule, but any Mannheim slide rule manual can be use as reference.

Click on the next link to see professional panoramic pictures of the 357 & 367 models:

https://www.sliderulemuseum.com/Faber/AW_Faber_DecimalKeeper_c1887-1899.jpg

https://www.sliderulemuseum.com/Faber/AW_Faber_367_DecimalKeeper_GiftOfPhilipRodley.jpg

References:

• Holland, Peter: Slide Rules. A.W. Faber-Castell, Models, Types, Scales. German-English Catalog. English Translation by Peter Holland, 2020 https://www.sliderulemuseum.com/Catalogs/Rechenschieber_AWFaberCastell_SlideRules_byPeterHolland_ed8.pdf

• Catlow, Trevor: Suggestions for Dating pre-1920 Faber-Castell Slide Rules. Slide Rule Museum https://www.sliderulemuseum.com/Papers/Catlow_%20Dating_Pre-1920_Faber-Castell_SlideRules.pdf

• Colin Tombeur: Overview of A.W. Faber-Castell Slide Rule Dating Chronology 1892-1920. http://www.andtheugly.com/slides/srman/TC02_Chronology_Overview_v1w.pdf

• Catlow, Trevor: The Earliest Faber Slide Rules. www. andtheugly.com, August 2017. http://www.andtheugly.com/slides/srman/TC03_Earliest_v1w.pdf

• Chamberlain, Edwin: Slide Rule Decimal Point Location Methods. The Journal of the Oughtred Society. Vol. 7, 1 Spring 1998. http://www.oughtred.org/jos/articles/V7.1_Chamberlain_Decimals.pdf

This is another good and interesting reference about how to handle the decimal point in basic operations with the Mannheim Slide Rule:

• Scheffler, Robert B:: Department Store Statistics with he Aide of the Slide Rule. Published by Robert B. Scheffler, Chicago 1914. pp 33-36. https://drive.google.com/file/d/1dQJarQd2ZtSd1EsAqzCVMhTyKS5mvK8a/view?usp=sharing