Scale.
1. A measure divided into equal parts, usually main divisions and subdivisions; as inches and octonary fractions for carpenters' work, decimal divisions and subdivisions for chain-work, duodecimal for plotting carpenters' work which is in feet and inches.
The meter and its decimal subdivisions are also sometimes employed.
Used by surveyors, architects, and draftsmen for laying down work on paper.
Among the kinds may be cited the following, but some of the names are synonyms: —
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| Architect's scale. | Pocket-scale. |
| Drafting-scale. | Protracting-scale. |
| Engineer's scale. | Sector-scale. |
| Gunter's scale. | Slide-rule. |
| Mathematical scale. | Sliding-scale. |
| Micrometer-scale. | Tailor's scale. |
| Offset-scale. |
Some of these are considered under these heads.
They are made of
| Aluminium. | Ebony. | Palladium. |
| Beech. | German-silver. | Paper. |
| Bone. | Glass. | Silver. |
| Box. | Horn. | Steel. |
| Brass. | Ivory. |
Scales are variously graduated, so that certain simple relations between numbers, trigonometrical lines, etc., may be ascertained by inspection.
To this class belong the sector (which generally forms part of a case of
mathematical instruments);
Gunter's scale, and
Dr. Wollaston's scale of chemical equivalents.
See list under calculating and measuring instruments.
2. A balance for weighing; in this sense the word is usually employed in the plural.
They frequently receive special names, as —
| Coin-weighing machine. | Spring-balance. |
| Counter-scales. | Steelyard. |
| Platform-scales. | Weighing-machine. |
Some of which are considered under their respective heads.
See also balance, page 213.
Weighing-machines and scales, measures, and weights have, in some form, been in use from time immemorial.
Pliny states that they were invented by
Phidon of
Argos, or, according to
Gellius, by
Palamedes.
Many centuries before this time, however, Abraham, 1860 B. C.,
weighed out “400 shekels of silver, current money with the merchant,” to Ephron the Hittite, as payment for a piece of land, including the cave and all the standing timber in the field and the fence.
This sale was made in the presence of witnesses, and is believed to be the earliest transfer of land of which record survives.
In ancient
Egypt the superintendence of weights and measures belonged to the priests until the privilege was removed from them by the Romans.
The scales were in the public market, and recourse was had to them by buyers and sellers.
The practice still prevails to a great extent in modern
Egypt.
The same mode was adopted in
Greece, as we read: “As the civil magistrate weighs bread in the marketplace.”
The scales were erected temporarily, and had the ordinary “beam suspended from a stirrup at its midlength.”
The weights, like the money, were in the form of rings, as may be seen in a number of places on the Theban tombs.
See coining.
Large scales were flat wooden boards, each attached by four ropes to a ring at its respective end of a beam, which was supported by a middle ring, suspended from the standard post.
The steelyard is a Chinese invention.
Wilkinson failed to find it at
Thebes or Beni Hassan.
It was used in
Rome under the name of
statera. See balance; weigh-ing-machine.
The illustration is from an ancient
Egyptian papyrus in the British Museum, representing the “Ritual of the dead” of Hennefer, superintendent of the cattle for Seti I., about 1350 B. C. The heart of the deceased is being weighed before
Osiris in the
Hall of Perfect Justice.
It will be noticed that the balance-beam is not suspended from the middle with a series of weights, like the modern scale, nor in the manner of the
statera, or steelyard; but it has a shifting fulcrum, by the adjustment of which the differences of the weight of the articles may be ascertained.
The
lever-scale, on the principle of the steelyard, has for 40 years been used in the
United States, for all purposes, from that of a letter-weigher to that of the weigh-lock scale.
The former weighs to half-ounces, and the latter to 1,200,000 pounds. Here this principle is supreme; in
England it is yet far otherwise.
The ordinary balanced beam, with a number of iron weights, 112 pounds each, in one scale and the hogshead of sugar or what not in the other, was the ordinary means of weighing in the
London Docks, a few years since, and may be yet.
Platform-scales were probably in use in
England in 1796, one being patented in that year by Salmon.
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|
Platform-scales. |
In the ordinary platform-scale (
A,
Fig. 4654), the platform
a has a downwardly projecting steel-faced plate at each corner, which rests upon the knife-edges
b of the levers
c; the downward motion of the free ends of the levers is limited by loops
c′. The platform is steadied by check-rods
d connected to it and to the scale.
 |
|
Platform and scoop scale. |
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The
Howe scale
B has adjustable bearings
e at the corners of a framework resting upon the knife-edges
b; balls
f are interposed between this framework and the platform for obviating jar and friction on the knife-edges when a weight is placed on the scale and the check-rods are dispensed with.
See weigh-ing-machine, for the larger kinds.
Fig. 4655 is a combination of the platform and scoop scale, in which one graduated beam is connected to both the platform and scoop, so that the weight of articles placed on either is indicated on the beam, without the necessity of adjusting any part of the scale.
By the proportioning of the leverages, the weight on the beam will balance much heavier articles on the platform than in the scoop.
Fig. 4656 shows three forms of scale for factory purposes.
a is a
yarn scale for sizing.
One
lea or
cut of 120 yards is used.
b is a
lap scale to weigh quantities of cotton or wool, to be spread on the feedapron of the cardingmachine.
c is a form of scale for weighing yarn, roving, drawing slivers, etc. See also counter-scale.
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|
Counter-scales. |
3. (
Cutlery.) One of the side plates of iron or brass which form the main portion of a pocket-knife handle, and to which the
sides of ivory, bone, wood, etc., are riveted.
4. A metallic plate worn instead of an epaulet by soldiers.
5. (
Metal-working.) The film of oxide which forms on the surface of iron or other metal when heated.
6. (
Steam.) The hard deposit which gathers in steam-boilers.
See incrustation, page 1177.
