Almost 4 years later ...
At least the upper scale of my caliper - labeled "Paris" and running backwards - found an explanation:
https://en.wikipedia.org/wiki/LigneOne "Ligne" (or Paris Line) is exactly 2.2558291 mm.
When I set the caliper to 10 Lines on the upper scale I get 22.5mm - q.e.d.
The middle scale - labeled "Englisch" - is still waiting for an explanation ....
At least the upper scale of my caliper - labeled "Paris" and running backwards - found an explanation:
https://en.wikipedia.org/wiki/LigneOne "Ligne" (or Paris Line) is exactly 2.2558291 mm.
When I set the caliper to 10 Lines on the upper scale I get 22.5mm - q.e.d.
The middle scale - labeled "Englisch" - is still waiting for an explanation ....
Attachments
Presumably: https://en.wikipedia.org/wiki/Line_(unit) - namely the 1/16th of an inch version, given 64 on that scale looks to be 101.6mm
Given the line/ligne units this might be a watchmaker's tool?
Given the line/ligne units this might be a watchmaker's tool?
It is simply a vernier caliper with a different base, a bit like the old slide rules.
You can work it out by measuring drill bits and comparing the readings with a normal caliper, say, 2, 4, 6, 8 and 10 mm bits.
They are accurately ground, and easy to find compared to gauge blocks.
If it says English, then it may be fractional markings rather than decimal markings.
Then look at the pictures of Vernier calipers from English makers, that should help.
You can work it out by measuring drill bits and comparing the readings with a normal caliper, say, 2, 4, 6, 8 and 10 mm bits.
They are accurately ground, and easy to find compared to gauge blocks.
If it says English, then it may be fractional markings rather than decimal markings.
Then look at the pictures of Vernier calipers from English makers, that should help.
It is indicating 22.5 mm on the line just inside the jaw on the lower scale...that is mm.
The upper scale is reading 36 + 10/36 divisions..
So it is a leigne vernier / plain mm caliper, no vernier scale for the mm, only for the Leigne scale.
That has a reversed 0-36 vernier scale, compared to the straight 0-9 I have used on metric calipers.
Will take some getting used to.
The upper scale is reading 36 + 10/36 divisions..
So it is a leigne vernier / plain mm caliper, no vernier scale for the mm, only for the Leigne scale.
That has a reversed 0-36 vernier scale, compared to the straight 0-9 I have used on metric calipers.
Will take some getting used to.
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The zero by the 150 reads 10, so a scale of 1/10ths of an inch, I presume none of the other scales could be obscure gauges ( wire/springe/sheet steel etc ) because they are generally exponential. Perhaps I can dig out an old mechanics year book and look through the pages of gauges. Unfortunately I only have half ( the moving part ) of the caliper - not like you rich folk with both bits.
My dad gave me a very old compass galvanometer in a wooden case, picked up at an antique store in the UK (not a family heirloom). Can't remember if it's packed away in storage or was disposed of in the delirium of moving. The coil was open-circuit; if it ever turns up again, I'll make an attempt at fixing it.
It looked very much like this one, down to the 3 binding posts and ring handle on top, but the back cover was hinged:
https://www.bonhams.com/auctions/23502/lot/536/
It looked very much like this one, down to the 3 binding posts and ring handle on top, but the back cover was hinged:
https://www.bonhams.com/auctions/23502/lot/536/
I think my dad had one but I never saw it after a house move. I can remember a meter with large dial and a mirror, big chunky knobs and the case being black. Pity - I could have used it!
Hmmm .... The upper scale is reading 36 + 10/36 divisions.. with "upper scale" you mean upper scale on the moving part, right.
but ... 10/36 of what ? and what does "English" mean in that context as it would refer to the vernier of a "French" scale ... Hmmm
100 on the upper scale on the moving part is about 64 on the lower scale.
To that extent, it is a dual scale vernier.
I have seen steel vernier calipers with inches and millimeter markings, with corresponding vernier markings. Much more recent than this, made until the 1970s.
This is similar, so I had suggested measuring known drill bits to find out what scales they are.
You could use tooth paste, or lemon juice, or brass polish to clean the markings on the lower fixed side, might be a vernier scale there too, obscured by the patina.
Clean off the residue from juice...mildly corrosive.
To that extent, it is a dual scale vernier.
I have seen steel vernier calipers with inches and millimeter markings, with corresponding vernier markings. Much more recent than this, made until the 1970s.
This is similar, so I had suggested measuring known drill bits to find out what scales they are.
You could use tooth paste, or lemon juice, or brass polish to clean the markings on the lower fixed side, might be a vernier scale there too, obscured by the patina.
Clean off the residue from juice...mildly corrosive.
The Swiss watch industry was mostly around Geneva, a French speaking part of Switzerland, and a lot of French words are encountered in Horology.
Now, a lot of them are closed for ever, only a few expensive makes remain.
1 ligne = 2.255...mm
See Wikipedia article, possibly a non linear or fractional scale existed, my browser is slow today.
I could not open the article.
Now, a lot of them are closed for ever, only a few expensive makes remain.
1 ligne = 2.255...mm
See Wikipedia article, possibly a non linear or fractional scale existed, my browser is slow today.
I could not open the article.
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