rivett608
Diamond
- Joined
- Oct 25, 2002
- Location
- Kansas City, Mo.
Sometimes you just get lucky. About a month ago I went to a very high quality antique shop in Copenhagen to look at and learn more about a 18th c. pair of candlesticks in their window that were similar to some I had seen at Rosenborg Castle. The shop had wonderful things that I would love to own but a little out of my reach. After talking to the friendly owner for nearly a hour he said he had some medical things and opened a drawer..... and my eyes spotted this. I knew it look familiar... but it took till I rode home on my bike and checked it out. WOW... was I surprised.... it is a perfect match in both illustration and description for the caliper shown in Bergeron's Manual du Tourneur 2nd edition of 1816. This to my knowledge is THE FIRST ILLUSTRATION of a vernier caliper making this a very early example and wonderful addition to my collection!!!!!!!
You can see the caliper listed as fig. 9.... here is a translation of Bergeron's text by Honrick.... he says it may not be perfect but I think he has the gist of it and I thank him for doing it. Yes I know it is long.... but that is the way the French write.... just skip this if you want to see more photos and restoration.....
Translation from Bergeron, Manuel Du Tourneur, 1816.
Volume II. Pages 8 - 11.
“Fig. 9 represents a kind of sliding compass, which we call Compass
Comparator.
It is formed of three blades of copper; two are fixed at A, on one of the heads
that has a point, leaving a space between them in which sits a third blade slightly
thinner than the other two, and the length of which is practiced with a groove in
the end we see at b.
At the other end of the inner blade is fixed the second head B, to which are
attached two copper cheeks, C, D, which slide along the outer blades and are
marked on both sides. The small bolt at the lower end of the blade holds the
inner blade, and therefore the head B, at the determined spacing. On both sides
of the compass are engraved the following measures: 1. “le pied de roi” (King’s
foot); 2. “le pied du Rhin” (Rhine foot); 3. English foot; 4. the circumference of
a circle whose diameter is known, calculated on the report of Archimedes, that is
to say to twenty-two.
We have followed the description of the compass before us, which has been
provided by a distinguished amateur, but we feel it would be easy to substitute
any other measure for the first three: for example, the metric foot instead of the
English foot, etc. We might also, for the fourth, use the report of 113 / 355 found
by Adrian Metius, which is more accurate than 7 / 22. [113 divided by 355
= 3.1415929 or pi.]
Both cheeks, C, D, have on their face a similar division of the vernier
graphometers [Vernier scale], and whose use is roughtly the same.
This division takes in nine lines of the measure marked on the corresponding
face, dividing it into ten equal parts. At the point where this division begins a
zero is marked lengthwise by a small bar. When this small bar is not located
just in front of a division line, it is found how many tenths of lines it is remote, by
counting the devisions of the vernier until one of its divisions coincide with those
of the rule.
The purpose of this instrument are quite numerous; it is:
1. To compare the three measures that are engraved. If, for example, we
want to know how much 3 inches 4 lines, “pied de roi,” equals in inches and
lines, “pied du Rhin,” we move the head B until the zero bar on the “pied de roi”
vernier scale is at 3 inches 4 lines. We turn the compass over, and we see that
the zero bar on the “pied du Rhin” vernier scale is at 3 inches, 5 lines, and 4
tenths of a line.
It would be the same if one wished to compare other measures marked on
the faces of the compas.
2. Calipers all pieces round, flat, or square. Simply grasp the piece between
the two steel heads and the zero indicator of any one of the measures will
indicte the thickness or diameter of the piece.
3. To measure the depth of a hollow piece, a rebate, or any ledge on a round
or straight piece. To do this the lower end of the inner blade is extended
downward, until it touches the bottom of the recess, and the outer frame is
lowered until it touches the upper edge of the piece. The zero indicators mark
the depth of the recess.
4. It indicates immediately and without error a tenth line for the circumference
of a circle whose diameter is known. For example, we want to know what is the
circumference of a circle whose diameter is 2 inches 7 lines, we place the zero
vernier indicator of the “pied de roi” at the division, and the vernier zero indicator,
corresponding to the division drawn on the same blade, indicates a
circumference of 8 inches, 1 line, 4 tenths of a line.
We observe here that the circumferences are calculated for diameters whose
dimensions are in parts of “le pied de roi.” If the given diameter was a factor of
“le pied du Rhin” or other measures, it would be necessary to first change it to
“pied de roi” inches and lines, and see the corresponding number on the
circumference scale, then we would know the result for the “pied du Rhin.”
These reductions are made by the instrument, and present no difficulty.
5. Finally a point about the methods of measuring just described, so as to be
able to use them as needed. This advantage is not the least of those that the
comparative compass provides, and the Amateur who wants to draw a machine,
or reduce it proportionately, will feel the full value.
But we will add here that the merit of this instrument depends entirely on the
accuracy of the divisions and the precision of its adjustment, and we would urge
those who procure this type of instrument to carefully check before using it.
The groove for the middle blade may be shaped like a rack. Then, through a
gear at the end of the frame the blade is moved forward or backward more easily.
This adjustment works well, however there are cases where the thickness of the
gear can interfere. Besides, the movement is a bit slow, and we believe the first
method is the preferred method, being simpler and requiring less time.
An instrument of this kind, which, instead of the different measures we have
described, is engraved with a single measure on each side, such as “le pied de
roi,” and the development of circumferences with a vernier indicating twentieths
of lines on one side and twenty fourths of lines on the other side, divisions easy
to distinguish with the naked eye, would be invaluable in the practice of the
sciences and the arts.”
You can see this is a perfect match... even to the scales on it...
Now who made mine? I don't know.... it is engraved "H. Plőtz ou Copenhaguen"...... is this a maker or owner? There were not a lot of tool makers working in Copenhagen at that time, also if it was made in Copenhagen why didn't he use Danish or German ?(a language used at court sometimes) to describe the scales and then there is the spelling of Copenhaguen, this is a odd European spelling still sometimes used. But the engraving looks similar...... or is it? I would think a professional engraver would be able to space his letters out to get it on one line? Anyway what we can tell is this tool has been in Copenhagen for a very long time.
The more I think about it I feel it came from Bergeron's shop in Paris..... another little detail is the tools sold from that shop were almost never signed.
Now mine was missing a screw...... but looking at the staining it looked more like a knob. I could figure out the size from the shadow it left.... but the engraving showed a wing nut???????
I found this photo in Nessi's wonderful book Antique Tools & Instruments (if you like pretty photos of great early tools this is a must!) and it shows a similar caliper set into a drawing set.... with a knob!
You can see the caliper listed as fig. 9.... here is a translation of Bergeron's text by Honrick.... he says it may not be perfect but I think he has the gist of it and I thank him for doing it. Yes I know it is long.... but that is the way the French write.... just skip this if you want to see more photos and restoration.....
Translation from Bergeron, Manuel Du Tourneur, 1816.
Volume II. Pages 8 - 11.
“Fig. 9 represents a kind of sliding compass, which we call Compass
Comparator.
It is formed of three blades of copper; two are fixed at A, on one of the heads
that has a point, leaving a space between them in which sits a third blade slightly
thinner than the other two, and the length of which is practiced with a groove in
the end we see at b.
At the other end of the inner blade is fixed the second head B, to which are
attached two copper cheeks, C, D, which slide along the outer blades and are
marked on both sides. The small bolt at the lower end of the blade holds the
inner blade, and therefore the head B, at the determined spacing. On both sides
of the compass are engraved the following measures: 1. “le pied de roi” (King’s
foot); 2. “le pied du Rhin” (Rhine foot); 3. English foot; 4. the circumference of
a circle whose diameter is known, calculated on the report of Archimedes, that is
to say to twenty-two.
We have followed the description of the compass before us, which has been
provided by a distinguished amateur, but we feel it would be easy to substitute
any other measure for the first three: for example, the metric foot instead of the
English foot, etc. We might also, for the fourth, use the report of 113 / 355 found
by Adrian Metius, which is more accurate than 7 / 22. [113 divided by 355
= 3.1415929 or pi.]
Both cheeks, C, D, have on their face a similar division of the vernier
graphometers [Vernier scale], and whose use is roughtly the same.
This division takes in nine lines of the measure marked on the corresponding
face, dividing it into ten equal parts. At the point where this division begins a
zero is marked lengthwise by a small bar. When this small bar is not located
just in front of a division line, it is found how many tenths of lines it is remote, by
counting the devisions of the vernier until one of its divisions coincide with those
of the rule.
The purpose of this instrument are quite numerous; it is:
1. To compare the three measures that are engraved. If, for example, we
want to know how much 3 inches 4 lines, “pied de roi,” equals in inches and
lines, “pied du Rhin,” we move the head B until the zero bar on the “pied de roi”
vernier scale is at 3 inches 4 lines. We turn the compass over, and we see that
the zero bar on the “pied du Rhin” vernier scale is at 3 inches, 5 lines, and 4
tenths of a line.
It would be the same if one wished to compare other measures marked on
the faces of the compas.
2. Calipers all pieces round, flat, or square. Simply grasp the piece between
the two steel heads and the zero indicator of any one of the measures will
indicte the thickness or diameter of the piece.
3. To measure the depth of a hollow piece, a rebate, or any ledge on a round
or straight piece. To do this the lower end of the inner blade is extended
downward, until it touches the bottom of the recess, and the outer frame is
lowered until it touches the upper edge of the piece. The zero indicators mark
the depth of the recess.
4. It indicates immediately and without error a tenth line for the circumference
of a circle whose diameter is known. For example, we want to know what is the
circumference of a circle whose diameter is 2 inches 7 lines, we place the zero
vernier indicator of the “pied de roi” at the division, and the vernier zero indicator,
corresponding to the division drawn on the same blade, indicates a
circumference of 8 inches, 1 line, 4 tenths of a line.
We observe here that the circumferences are calculated for diameters whose
dimensions are in parts of “le pied de roi.” If the given diameter was a factor of
“le pied du Rhin” or other measures, it would be necessary to first change it to
“pied de roi” inches and lines, and see the corresponding number on the
circumference scale, then we would know the result for the “pied du Rhin.”
These reductions are made by the instrument, and present no difficulty.
5. Finally a point about the methods of measuring just described, so as to be
able to use them as needed. This advantage is not the least of those that the
comparative compass provides, and the Amateur who wants to draw a machine,
or reduce it proportionately, will feel the full value.
But we will add here that the merit of this instrument depends entirely on the
accuracy of the divisions and the precision of its adjustment, and we would urge
those who procure this type of instrument to carefully check before using it.
The groove for the middle blade may be shaped like a rack. Then, through a
gear at the end of the frame the blade is moved forward or backward more easily.
This adjustment works well, however there are cases where the thickness of the
gear can interfere. Besides, the movement is a bit slow, and we believe the first
method is the preferred method, being simpler and requiring less time.
An instrument of this kind, which, instead of the different measures we have
described, is engraved with a single measure on each side, such as “le pied de
roi,” and the development of circumferences with a vernier indicating twentieths
of lines on one side and twenty fourths of lines on the other side, divisions easy
to distinguish with the naked eye, would be invaluable in the practice of the
sciences and the arts.”
You can see this is a perfect match... even to the scales on it...
Now who made mine? I don't know.... it is engraved "H. Plőtz ou Copenhaguen"...... is this a maker or owner? There were not a lot of tool makers working in Copenhagen at that time, also if it was made in Copenhagen why didn't he use Danish or German ?(a language used at court sometimes) to describe the scales and then there is the spelling of Copenhaguen, this is a odd European spelling still sometimes used. But the engraving looks similar...... or is it? I would think a professional engraver would be able to space his letters out to get it on one line? Anyway what we can tell is this tool has been in Copenhagen for a very long time.
The more I think about it I feel it came from Bergeron's shop in Paris..... another little detail is the tools sold from that shop were almost never signed.
Now mine was missing a screw...... but looking at the staining it looked more like a knob. I could figure out the size from the shadow it left.... but the engraving showed a wing nut???????
I found this photo in Nessi's wonderful book Antique Tools & Instruments (if you like pretty photos of great early tools this is a must!) and it shows a similar caliper set into a drawing set.... with a knob!
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