BISCHOFF
letter scale
maker: V. Bischoff, Munich, Germany
design: Alois Heckenstaller, Straubing (Bavaria)
Bischoff letter scale
| This huge letter scale bears the name of the maker V. Bischoff from Munich in Germany. The stand height of this letter scale is 50 centimeters, the highest point of the suspension bracket of the scale is even 55 centimeters high. The designer of the letter scale is Alois Heckenstaller, from Straubing in Bavaria. This is stated in a German patent DE36955 that was already granted on July 22, 1885! Characteristic is the low-friction bearing with still a large angle of movement: a knife-edge support rests in a pan which in turn is movable mounted thanks again to knife-edge bearing. Also the suspension bracket of the hanging scale part has a knife-edge bearing. This results in an extremely sensitive scale. This letter scale is numbered 3321. This number is on a lot of the parts. A view small parts only have the last two digits: 21. The back of the figures scale has in addition to the whole number 3321 and the truncated number 21 the name BISCHOFF in stamped-in letters, and no initial here. I don't know when this letter scale was produced nor when it was verified for the first time. Maybe the verification office has the answer to the last question. These letter scales were used until the eighties of the last century and verified by the German Verification Offices for example Eichamt Bayreuth. This specimen was disapproved by that Office. With a lead secured wire a card of disapproval was attached to the base of this letter scale. According to this card the letter scale needs to be offered for recalibration before April 15, 1973. I removed the card and and overhauled the light damaged knife-edge bearing myself. As to proof verifications year marks are stamped into the lead bet of the weighing arm. These year marks are partly scratched off, 53, 60 and 63 still can be distinguished. This Bischoff has a unique double scale: with the weight folded up the top scale of zero to 250 grams is used, when the weight is folded down, the scale of 250 to 500 grams has to be used.
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back of the letter scale
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This letter scale is due to the implemented size, and thanks to the applied technology good to read per gram in both weighing ranges. The letter scale has a small brass weight hang on a thread, this serves as an aid to put the letter scale level with the two set screws. The stand is attached to the three-legged base by a large butterfly nut. More Bischoff letter scale models do exist.
Letter scales by Bischoff are more comprehensive written by Rein Kok in Meten & Wegen, the journal of the Dutch collectors society GMVV.
Een brievenweger met messen, van Bischoff uit München, Kok R.J., Meten & Wegen, nr. 149, maart 2010, pp. 3555-3561
Een bijzondere brievenweger van Bischoff, Kok R.J., Meten & Wegen, nr. 154, juni 2011, pp. 3672-3674
Later, these articles are taken up in the English language in Equilibrium.
A German Letter - Scale, Rein Kok, EQM 2008, No.3, pp. 3379-3381
A German Letter - Scale (part 2), Rein Kok, EQM 2009, No.2, pp. 3463-3466
Also the journal of the German society Mass & Gewicht has a short article:
M&G Heft 87 Sept. 2008, pp. 2147-2149 Ulrich Biber wrote the article: Patent und Ausführung
Below some more pictures of this huge Bischoff letter scale.
animation: unloaded scale
with folded up counterweight /
folded down counterweight
while loaded with 250gr. |
the drawings of the patent DE36955 of Alois Heckenstaller from 1885
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animation: with folded down
counterweight loaded with
250 grams and loaded to
the maximum of 500 grams |
the house for the knife-edge
and pan bearing |
the house from above
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mid right a stop ridge
to limit the movement |
knife-edge bearing of
suspension bracket |
V. Bischoff
München
scale number 3321 |
thread with brass weight
is an aid for leveling |
year verification marks
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side view
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card of disapproval
with broken wire and lead
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start of scale with number 3321 and the
letters P.W. meaning unknown to me |
scale middle
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scale end
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three legged base with 2 leveling screws
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the large butterfly nut
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one of the two leveling screws
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the illustration in a review in the Papierzeitung no. 79
from 1893 on page 2418
N.B. there is a clamp at the scale foot that can replace the letter plate |