Rocker scale/balance for Sovereigns/Half Sovereigns: usage etc
NildramUser
Sovs/Half Sovs, as e.g. the Fisch gauge doesn't cover Half Sovs.
I was wondering if anyone had any specific observations regarding
correct use of these devices; Marsh's books on the Sovereign and Half
Sovereign simply say that these Victorian era scales are generally
accurate and that a genuine coin will simply tip the balance.
(The device combines a weight test with a gauge test so a coin too thick
or of the wrong diameter will be rejected). However they don't specify
if the 'horned'/'antennae' end of the scale balance where the coin sits
should touch the surface on which the scale/balance is sitting.
Also, in the case of the balance I purchased,
- when placing a coin for weighing, the balance may not tip initially;
sometimes one needs to wiggle the weighted end of the balance on its
mounting as there is some 'give' in the spindle on which the lever
rests. Is this standard routine? I have tested a known good (via the
Fisch) Sovereign and the balance exhibited this behaviour; after
wiggling, the scale tipped.
- the scale I bought seems slightly off-whack (I posted some small
images of it at the urls below, about 34k each) in as much as the level
bar is raised upwards to the left in the horizontal plane when viewed
from the 'horned'/antennae end. Would this be likely to affect its
weighing accuracy or is its design intentional? The scale came with the
original cardboard box which tho' scuffed is not crushed and I would
expect a brass scale to crack or distort rather uneasily and in any
event not bend smoothly if subjected to the necessary force.
Here are the images (RockerScale01.jpg - RockerScale05.jpg), they may be
handy comparison viewing for others who may have been thinking of
purchasing one of these devices:
http://www.sendspace.com/file/r2wp3b
http://www.sendspace.com/file/sq23it
http://www.sendspace.com/file/d124r2
http://www.sendspace.com/file/zlarwo
http://www.sendspace.com/file/tzrlln
So in summary:
1) should the scale tip to touch the surface on which the balance is
mounted or just tip?
2) is the skewing of the level bar likely to indicate damage/affect
weighing accuracy?
3) when placing the coin in a tray to weigh, does one manipulate the
balance end somehow if it is initially 'stuck' and the balance does not
tip?
NildramUser
rwj@[MUNGED]gotadsl.co.uk.invalid says...
There probably isn't anything quite so solipsistic as anwering one's own
usenet post, but in the interests of diffusing some relatively arcane
information I have uncovered, here goes....
Since posting I have had sight of a hard copy of the revised 2001 edition
of the late Michael A. Crawforth's booklet "Sovereign Balances, 1-Standard
Rockers" which addresses some of the issues concerning usage of these
rocker balances. In material part it says:
"Difficulty arose in determining which beam response should
indicate true weight - should it balance level or tilted down?...
Most examples were made with the beam already level when
unloaded, and could only be used with some degree of tilt. On the
other hand, one balance had knife-edges and bearings which could
only balance level, and could not be fully tilted. Thus, the author
has come to the conclusion that although some balances were made
to balance level, in the tradition of scales, the majority were
intended to tilt fully down with a coin of the correct weight.
..."
The booklet contains interesting charts on pages 24 and 26 showing how
most of the balances exhibited some inaccuracy in gauging exact weight.
However, on page 25 Crawforth states:
"The performance of a rocker is determined by two criteria, - the
sensitivity with which it tips when loaded, and the accuracy with
which it has been adjusted for the weight of the coins. In checking
the performance of 87 sovereign rockers, the author found that
sensitivity was surprisingly good, and the beam turned, typically,
with l/4 grain, when loaded. Accuracy, however, was poor. Only ten
balances were correct for the sovereign, and 21 were correct for the
half-sovereign.
... In most cases, the sovereign facility was the less
accurate, and the error tended to be overweight, rather than underweight;
i.e. a weight greater than a true sovereign was required to
make the beam tip. ...
It would appear from this that high accuracy was not sought by most
of the public, and that all they needed was reliable detection of gross
wear, filed coins or counterfeits. The detection of counterfeits was
all the makers claimed, and for this purpose, the sovereign rocker
was more than adequate."
There is also some excellent information on Sovereign rocker balances on
one of the websites maintained by an ebay seller, surnamed alice-lewis.