John Bates hopes that TATHS may be able to help the Traditional Tools Group  in Sydney with an unusual micrometer.

Mahr Micrometer1A  fellow TTG member recently sent details of a Carl Mahr micrometer.

His problem was that he did not know what the numbers stamped on the frame were.

It is an old micrometer my guess would be early 1900s. Metric graduations with a range of 0 to 35 mm by 0.01 mm. There are 10 sets of figures which are multiples of 7.78 – why?

Have attached a couple of photographs. Any assistance greatly appreciated. 

Mahr Micrometer2

Mahr Micrometer3


John Bates
TTTG Secretary


Some further illustations provided by Wolfgang Jordan - see comments below 





Mikrometer Mahr Esslingen2


 Tabelle Schmiedeeisen 3


#1 Webmaster 2016-08-14 19:23
I have found an illustration of this exact micrometer. The catalogue was published in 1910 by the German dealer Delisle & Ziegele. The tool was described as follows:

No. 1033 Micrometer
in precision design
Micrometer indicating 1/100 mm or 1/1000 english inches.
The table of weights on the C-frame gives the weight of sheet iron and sheet metal per square meter, e.g. 1 square meter of sheet metal with a thickness of 1 mm weighs 7,78 kg, with a thickness of 2 mm 15,55 kg etc.

Dimensions and Prices.
Opening goes from 10 to 100 mm
Price per piece 3.50 to 28 Mark
Additional price for nickel plating 0.25 to 0.90 Mark
Additional price for Gef├╝hlsschraube (some kind of coupling between handle and shaft to guarantee equal pressure) 0.80 Mark
Additional price for Klemmschraube (clamping screw) 0.80 Mark

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