Slide rules HOME page COLLECTION 10" RULES GERMANY
Make Faber Castell, Germany
Model 1/54 Darmstadt
Notes

1. This another case where I show three rules made at different times - in this case separated by over 20 years. The differences are relatively minor; different labelling of the scales, a different arrangement of the window for the log-log scales and additional hair lines on the cursor.
2. This rule is a Darmstadt - named after the technical college in that German city. Interestingly the city of Mannheim is not far away and whilst this is also the name of one of the other standard slide rule scale layouts there is no (direct) connection; Mannheim was a French artillery officer.
3.  The log-log scales are on the rear of the slide and accessed via a plastic "window" on the back of the rule. This makes good sense, as whilst the log-log scales  are used in conjunction with the C and D scales for raising numbers to a   non-integer power, the result cannot be carried directly forward into other calculation. For example to calculate 2.5 * (6.1)0.75 you would have to calculate the value of (6.1)0.75 first, note down the answer and then multiply that by 2.5. Perhaps this explains why this layout was so successful over so many years.
4. The log scale and the trig scales are on the top and bottom edges of the ruler respectively and are accessed by extensions to the cursor. Although the cursor construction changed with different models, the same principle continued to be used.
5. The cursor construction in the 1945 model is perhaps the most unusual as it used metal clips to hold together the three pieces of glass.
6. The labelling of the scales also evolved. The makers name does not appear of the face of the 1945 model. It also seems strange that the D and P scales should be the only scales with labels on the earlier versions.
7. The stock and the slide are of wood and have metal inserts. The later model has added plastic at the back of the rule. The 1945 model I have, in excellent condition overall, is slightly bowed as if the plastic has shrunk more than the wood. It could be that the extra plastic was added to maintain a better balance and prevent this. Though that said the 1952 model has the same construction as the 1945 model and does not show any bowing.

Front view
1007-faber-castell154-01.jpg (29053 bytes)
Detail -  front left - 1945 model
1007-faber-castell154-11.jpg (61013 bytes)
Detail -  front left - 1952 model
1007-faber-castell154-02.jpg (24711 bytes)
Detail -  front left - 1967 model
1007-faber-castell154-08.jpg (19549 bytes)
Detail - left back -1945 and 1952 models
1007-faber-castell154-04.jpg (19267 bytes)
Detail - left back - 1967 model
1007-faber-castell154-10.jpg (19068 bytes)
Detail cursor - 1945 model
1007-faber-castell154-12.jpg (20851 bytes)
Cursor -1952 model
1007-faber-castell154-07.jpg (32485 bytes)
Cursor - 1967
1007-faber-castell154-09.jpg (25515 bytes)
Front view
1007-faber-castell154-05.jpg (17171 bytes)
Detail - left front
1007-faber-castell154-06.jpg (23875 bytes)
Manufacturing dates 1945, 1952 and 1967
Length 10"
Material Plastic on mahogany
Scales L,K,A[B,C1,D/ L1,L2,L3] D,P,S,T
Gauge points p: 3.14: A,B,C1,C,D
Q,C,D
Cursor On 1945 model, glass with metal clips.
On later models, plastic. Screwed on plastic plates at top and bottom enable upper and lower edge of rule to be used.
Hair lines From the right hairline to the central one Ö p/4.
From the right to the left hairline 736 (French HP to kW)
On the later model only:
HP conversion for use with A scale.
p/4 for the A scale.