compass/caliper (UNCLASSIFIED)

victor steinbok aardvark66 at GMAIL.COM
Sat May 7 08:34:33 UTC 2011


I was most familiar with vernier calipers because that's the kind I grew up
with, in a sense (we used them regularly in shop lessons in school, believe
it or not). But I was not sure what to call the entire group that looked
similar and combined three types of measurements, so I started calling them
"universal/slide calipers". Turned out pretty close to the "official"
name--good to know. Incidentally, micrometers can also have all three types
of measurement scales--vernier, dial and electronic.

I always wondered about the origin of "vernier"--sounded vaguely French and
looked like a name, but, lacking history, it was hard to connect to
anything. Here, the OED helps: "the name of the inventor,
Paul Vernier (1580–1637), a French mathematician, who described the device
in a tract on the Quadrant Nouveau de Mathématiques published in 1631."

Some minor quibbles with OED listing of "vernier". I've included all three
entries below the signature. Both 1.a. and 1.b. have been pushed back below.
In addition, Vernier's name needs correction.

The definition in 1.a. is missing one nuance--"Vernier" did not always refer
to a single device, but to one of several detailed scales in a device, such
as a fine telescope or a octant (which, for a time, went by "quadrant"). So
you could have multiple verniers on a single "device"--as, for example, in
this table:

An odd thing about this particular volume--according to the GB tag, it
predates the Rees Cyclopaedia (1802+) by good 14 years (1788). The volume
came from Oxford (Bodleian), and there is no WorldCat record--it appears to
be a unique collection of excerpts from Rees that had been written by W.
Pearson. But at the bottom of page 31 ( ) there is a
reference to a volume published in 1799. So there is no chance of
antedating. But the term "Vernier" appears on almost every page, often
several times, usually in sense 1.a., but occasionally 1.b., but most of the
time referring to a particular set of markings on the adjustment rings on a

Here is a contemporaneous definition of Vernier:
[GB claims the volume for:  The Mosaic Theory of the Solar, or Planetary,
System. By Samuel Pye. London: 1766]
A Treatise on Practical Astronomy. By S. Vince. Cambridge: 1790
Chapter 1. On the Vernier. p. 1

> The Vernier (which took its name from the inventor) is a graduated index
> moveable against the arc of a quadrant, or any other graduated line, in
> order to carry on subdivisions to a greater number and to a greater degree
> of accuracy, than could be done by actual division ; and as this is now
> generally applied to all astronomical instruments, it was thought proper to
> begin with its description and to explain, once for all, its Principles and
> Use.

p. 3

> The divisions of the vernier scale now begin from one extremity ; formerly
> they were made to begin at a point in the middle and were numbered both ways
> from it, but that method was very inconvenient, and subjected the reading
> off to be more liable to mistakes.

Science makes progress--who knew! Note that the term is not applied to the
"device" as the OED definition suggests, but the gradation on it. Of course,
we can also differ about the definition of "device". There are also 54+
pages with hits for "vernier", including "vernier set" and "vernier plate"
(but it's close to the early OED date--1788--even though it predates the
second example--1797).

Speaking of devices, is there any reason Hadley's Quadrant is not listed
under Hadley in the OED? There are several meteorological terms from the
20th century (apparently named for a different Hadley--George) but nothing
that's actually nearly contemporaneous with the man (John Hadley,
1682-1744). Note that the first Vernier example and the one above both are
focused on Hadley's Quadrant. Perhaps it has something to do with the fact
that naming the instrument after Hadley impinges on Newton's primacy in
inventing it.

I previously mentioned the similarity of vernier calipers to a slide rule.
This led me to question the early example of "slide-rule" that the OED
picked up from Pepys diaries.

1663    S. Pepys Diary 14 Apr. (1971) IV. 103,   I walked to Greenwich,
> studying my slide-rule for measuring of timber.

I believe this citation is incorrect. The next citation shows up in 1838
(although, I am sure, it can be improved). And the line from Pepys clearly
refers to measurement. I propose that Pepys was actually referred to a set
of slide calipers used for measuring timber. Compare that to the set of
examples for caliper 1.b.:

1708    J. Kersey Dict. Anglo-Britannicum,   Callipers, an instrument made
> like a Sliding-Rule, to embrace the two Heads of a Cask, or Barrel, in order
> to find the length of it.
> 1876    Catal. Sci. Appar. S. Kens. No. 293,   Collection of Timber
> Callipers for the use of foresters.
> 1888    N.E.D. at Calliper,   Mod. techn. Calliper (in Liverpool timber
> yards), a rule for measuring timber, something like that which shoemakers
> use to measure feet.

Note, however, that "sliding-rule" was already available in 1708, but
certainly was not something available for "measuring timber"--that role
specifically belonged to calipers that were "made like a Sliding-Rule".

Another piece comes into view with multiple instance of "vernier" in 1773.
The Critical Review. Volume 35. May 1773
63. [Review of] Useful, Wasy, Directions for Seamen, who use Hadley's
Quadrant. Richardson and Urquhart. p. 399

> With regard to the work itself we find few articles in this account of
> Hadley's quadrant that have not been repeatedly described by other writers ;
> we must, however, in justice to the author, acknowledge that his
> illustration of the method for subdividing the degrees upon the arch of the
> quadrant, by means of the nonius or vernier is extremely explicit; this
> device, which is frequently called by the former of these names, was really
> the invention of one Peter Vernier, a gentleman of Franche Compte, and
> described by him in the French tongue, in a treatise on a new quadrant,
> published at Brussels anno 1631.

p. 400

>  Now, the degrees on the quadrantal arch being divided into 3 equal parts,
> therefore 7 degrees on it are divided into 21 equal parts; but an equal arch
> of the Vernier is divided into 20 equal parts, and, consequently, one of
> those divisions on the Vernier exceeds one on the quadrantal arch by of a
> degree, or 1 minute.

Now, this one actually follows the OED definition of a vernier as a
"device". But it refers to the inventor as Peter Vernier, rather than Paul
(the date of publication does match, on the other hand). This appears
between the first two citations for 1.a. (1766 and 1774).

The same volume, however, shows a third page with "Vernier".

The Critical Review. Volume 35. February 1773
[Review of] The Elements of Navigation ; containing the Theory and Practice.
With the necessary Tables. ... By Robertson, Librarian to the Royal Society.
p. 132

> The seventh section, and the following, called Practical Astronomy,
> describes in a clear and concise manner, the most useful instruments in an
> observatory, with the investigation of the Vernier scale, assigning minutes
> or seconds of an arc.

This one /does/ antedate 1.b. There is a copy of a later edition of
Robertson's book in GB (1780 -- ) There may also be
earlier editions (1754 and 1764), but they are far less developed than 3rd
and 4th. As is the case with the review, Robertson's originals--and Wilson's
"Dissertation" on the history of navigation attach to third and fourth
editions--refer to Peter Vernier, rather than Paul.

p. 271

> 5th. Its index or telescope. This, which is usually a brass tube containing
> the proper glasses and cross wires, is fixed near the object end to a brass
> plate, a little above a circular hole, or socket, in the plate : this socket
> goes round a collar concentric to the center, and fixed to the center-piece
> : so that, although the axis of the telescope does not, as a radius, pass
> through the center, yet it always keeps at the same distance from it in
> every position : to the eye-end of the tube is screwed a flat plate, which
> slides along the limb with the telescope ; this plate, called
> the Vernier, contains certain divisions, which used with those on the limb,
> give the angle to minutes or seconds of a degree, according to the size of
> the instrument : the beginning of the divisions called the index, on
> the Vernier, is as far distant from the axis, or line of collimation, as the
> center is ; and therefore the position of an object is given as truly, as if
> the line of collimation coincided with a radius.

This is the text from the 4th edition (1780). But the review above is of the
3rd edition, which should be substantially the same. Note, however, that
unlike the review above, the original of Volume I refers to "Vernier's
scale" rather than "Vernier scale", so it cannot be considered antedating

p. 274

> To the under part of the telescope is fixed a brass semicircle, of the same
> radius with the sextant, both arches having a common center-pin. In the
> semicircle is a groove cut through the plate parallel to its limb, to
> receive two screw-pins, which go into the sextantal arch near its ends ; by
> these screw-pins the two arches may be pressed close, and the telescope
> fixed in any desired elevation; which might be nearly ascertained, by
> graduating the semicircle, and putting a Vernier's scale on the sextant.

p. 278 refers to "Vernier's dividing plate" again, as well as "Vernier's
method", explaining how Vernier's method differs from Nonius's. p. 247 of
Volume 2 also mentions "Vernier's method", as well as "Vernier's scale".

On p. 248, however, we do find "Vernier scale":

Volume II. p. 248

> Now the middle line of the index D, which is the moveable radius of the
> quadrant, is the index, or pointer, of the Vernier scale, and is usually its
> middle line ; there being 10 divisions, or minutes, on each side, numbered
> 5, 10, to the right, and 15, 10, to the left; that is, the first 1 o minutes
> of the scale is reckoned in order from the middle line or index to the
> right; and the latter 10 minutes is to be reckoned from the left-hand end of
> the scale towards the right, and ends at the middle line, where the others
> began.

So, if Vol. 2 of the 1772/3 edition is found, it antedates the review by a
few months.

However, p. 249, p. 285, p. 297 go back to "Vernier's scale". So the missing
possessive on p. 248 may just be a fortuitous typo, except that it appears
again p. 296.

Luckily, the Nautical Almanac for 1769 offers an even earlier mention of
"Vernier plate".
Nautical Almanac and Astronomical Ephemeris, For the Year 1769. London: 1768
[multiple pages for Vernier 1.a., but only one for 1.b.]
p. 10

> The moveable Telescope, which is that used in taking Altitudes, turns round
> about the Centre of the Quadrant, and carries the Micrometer and both
> Vernier Plates along with it.

Still further back:
The Complete Dictionary of Arts and Sciences. By Temple Henry Croker, Thomas
Williams, Samuel Clark. Volume 3. London: 1766
Quadrant. Hadley's Quadrant. p. 76/1
The index D, is a flat bar, moveable round the center of the instrument ;
and that part of it which slides over the graduated arch, BC, is open in the
middle, with Vernier's scale on the lower part of it; and underneath is a
screw, serving to fasten the index against any division.

Again, it's only "Vernier's scale", not 1.b. Similarly, Robertson's 1st
edition of Elements of Navigation (1754 -- ) contains
two references to "Vernier's division or scale". Also, Hammond's Practical
Surveyor (1750) contains three references to "Vernier's scale" and one to
"Vernier's way", but fails to identify any device by that name ( ).

Vernier 1.a. can also be pushed back.
Navigatio Britannica: Or a Complete System of Navigation In all its
Branches, both with regart to Theory and Practice. By J. Barrow. London:
Sect. III. Of Cole's Quadrant. p. 140

> This useful Instrument, which is the Invention of Mr. /Benjamin Cole/, a
> most ingenious Mathematical Instrument-maker, at the /Orrey/ in
> /Fleet-street/, consists of six Parts, /viz/. The Staff AB (see Fig. 3.
> Plate 4.) the Quadrantal Arch /f g/, three Vanes A, B, C, and the Vernier G.

p. 141

> Set the Line G on the Vernier against 0 Deg. on the upper Limb of the
> Quadrant
> ...
> The Vernier G, is a Piece of Wood or Brass fastened to the Staff by a
> Screw, having a chamfered or sloped Edge, under which the outward Edge of
> the quadrantal Arch slides ; on this piece is a Scale of Divisions, serving
> to cut the Degrees on the Arch into single Minutes, which from its Inventor,
> is called /Vernier's Division/ ; whence the Piece, containing this Scale, is
> called the Vernier.

Now, returning to the name of the inventor: the OED claims it's Paul
Vernier. 18th century books claim it's Peter. Both appear to be wrong, but
the OED more so. The name is Pierre Vernier, French speaking mathematician,
born in Ornans within the Spanish territory, rather than French.
Unsurprisingly, his 1631 book was indeed published in Brussels. (See
Robertson citation above for details) Peter is the Anglicized version of the
name, but not Paul. I am not sure where the editors got that name. Ornans is
a part of the French-speaking territory that was a part of the Spanish
Hapsburg kingdom.

Robert Hooke refers to a method of division devised by Pierre Vernier
(1679). However, he does not identify it with any instrument. Similarly,
Benjamin Robin's identifies "Vernier's Method" with Peter Vernier of
Franche-Comte and correctly identifies his 1631 publication.

Robins also cites "Dr. Hook" giving credit to Vernier over Hevelius, which
unmistakably refers to the 1679 work of Hooke (above).


Etymology:  < the name of the inventor, Paul Vernier (1580–1637), a French
mathematician, who described the device in a tract on the Quadrant Nouveau
de Mathématiques published in 1631.

1. a. A device, consisting of a short movable scale, by which more minute
> measurements may be readily obtained from the divisions of the graduated
> scale of astronomical, surveying, or other mathematical instruments to which
> it is attached.Sometimes erroneously called a nonius (q.v.).
> 1766    Instruct. for Hadley's Quadrant 17   A scale of divisions graduated
> on the chamfered edge or sloped side of the index, which scale is called the
> vernier.

1. b. attrib. and Comb., as vernier circle, vernier division, vernier
> piece,vernier plate, vernier scale, etc.Also with the names of instruments
> or tools having a vernier scale or attachment, as vernier caliper,vernier
> compass, vernier transit (E. H. Knight Pract. Dict. Mech.).
> 1788    Encycl. Brit. II. 587/2   The first division of the vernier piece
> marked 15.
> 1797    Encycl. Brit. XVIII. 644/1   Vernier scale, a scale excellently
> adapted for the graduation of mathematical instruments.

2. Astronautics. Used attrib. and absol. to designate a small auxiliary
> rocket engine for effecting minor changes in the velocity or attitude of a
> spacecraft.
> 1958    Observer 12 Oct. 1/2   Eight small ‘vernier’, or guidance
> rockets,‥had been fitted to Pioneer. Any or all of these could be fired from
> the earth to make any necessary correction in the final phase of the flight.

On Fri, May 6, 2011 at 11:24 AM, Mullins, Bill AMRDEC <
Bill.Mullins at> wrote:

> The website and electronic catalog for Starrett has a great deal of info
> for calipers (you were pretty comprehensive, but left out hermaphrodite
> calipers).
> The class of calipers that makes inside/outside measurements and is
> somewhat similar in appearance to a slide rule is called "slide
> calipers", and includes electronic, vernier and dial measuring
> capabilities:

The American Dialect Society -

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