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"When a current is passed through the instrument it causes one end of the movable system to tilt downwards, and the other end upwards; the sliding weight is then moved along the tray by means of a silk cord until equilibrium is again established." —Encyclopedia Britannica, 1910

Lord Kelvin's Ampere Balance

"When a current is passed through the instrument it causes one end of the movable system to tilt downwards,…

An apparatus for weighing bodies.

Balance

An apparatus for weighing bodies.

A balance used for measuring weight.

Balance

A balance used for measuring weight.

"A representation of a common form of the delicate balances employed in physical and chemical researches. the beam is constructed so as to combine lightness with strength, and rests by a fine knife-edge on an agate plane. It is surmounted by a weight moving on a screw, so that the sensibility may be increased or diminished, according as weight is raised or depressed." — Chambers' Encyclopedia, 1875

Balance

"A representation of a common form of the delicate balances employed in physical and chemical researches.…

"The balance is essentially a lever of the first class, having equal arms. The beam carries a pan at each end, one for the weidhts used, the other for the article to be weighed." -Avery 1895

Balance

"The balance is essentially a lever of the first class, having equal arms. The beam carries a pan at…

"When bodies of equal weight are supported by the arms of a lever, they will balance each other when placed at equal distances from the fulcrum." —Quackenbos 1859

Balance

"When bodies of equal weight are supported by the arms of a lever, they will balance each other when…

"On this principle the common balance, represented [here] is constructed. A beam is poised on the top of a pillar, so as to be exactly horizontal. From each end of the beam, at equal distances from the fulcrum, a pan is suspended by means of cords. The object to be weighed is placed in one of these plans, and the weights in the other." —Quackenbos 1859

Balance

"On this principle the common balance, represented [here] is constructed. A beam is poised on the top…

These are three toothpick images that are balancing while standing sideways on each side.

Balance

These are three toothpick images that are balancing while standing sideways on each side.

In the common balance there is a stiff piece of metal called the beam, which turns about the sharp edge of a steel wedge forming part of the beam. The scale pans rest upon the hooks of the wedges.

Balance

In the common balance there is a stiff piece of metal called the beam, which turns about the sharp edge…

A balance of great delicacy with the glass case that contains it.

Balance for Purposes of Accuracy

A balance of great delicacy with the glass case that contains it.

An illustration of a balance scale.

Balance Scale

An illustration of a balance scale.

This antique Roman balance from Pompeii has one pan that hangs from a rod.

Antique Roman balance from Pompeii

This antique Roman balance from Pompeii has one pan that hangs from a rod.

"This is a very convenient and quite accurate method of determining specific gravity." — Ford, 1912

Beam Balance

"This is a very convenient and quite accurate method of determining specific gravity." — Ford, 1912

"The most accurate method of determining the specific gravity of a mineral is by the use of a chemical balance. To one beam of the balance is suspended a wire basket which is so arranged that it can be immersed in a beaker of water. The basket is hung in the water and then counterbalanced by weights on the opposite pan of the balance. The mineral specimen to be tested, having been first weighed on the balance in the ordinary fashion, is now placed in the basket under the water and weighed again." — Ford, 1912

Chemical balance

"The most accurate method of determining the specific gravity of a mineral is by the use of a chemical…

Chemical balance.

Chemical Balance

Chemical balance.

Coulomb's torsion balance is in the shape of a cylinder with the pan inside.

Coulomb’s torsion balance

Coulomb's torsion balance is in the shape of a cylinder with the pan inside.

"An apparatus designed to measure the elongation or contraction of a spring when attached to two scale-pans, with one immersed in water." -Avery 1895

Jolly Balance

"An apparatus designed to measure the elongation or contraction of a spring when attached to two scale-pans,…

An illustration of a precision balance.

Precision Balance

An illustration of a precision balance.

"A form of balance in which the weight of the body under examination is measured by the stretching (torsion) of an elastic wire in the form of a long spiral. A common use of the simple form of spiral balance is in determining the specific gravity of small fragments of minerals, which for this purpose are weighed first in the upper pan and then in that below, which is immersed in water." —Whitney, 1889

Spiral Balance

"A form of balance in which the weight of the body under examination is measured by the stretching (torsion)…

"Suspend two similar spring balances, A and B, from any convenient support, as shown. From the wooden rod carried by their hooks, suspend a known weight. Be sure that the dynamometers hang vertical, and therefore parallel. Record the reading of the dynamometers." -Avery 1895

Two Spring Balances

"Suspend two similar spring balances, A and B, from any convenient support, as shown. From the wooden…

The stability of the "balancer" depends on the fact that, owing to the weight of the two leaden balls, the center of gravity of the whole is below the point of support.

Balancer Toy Illustration

The stability of the "balancer" depends on the fact that, owing to the weight of the two leaden balls,…

These are two toothpick images that are balancing while on one knee.

Balancing

These are two toothpick images that are balancing while on one knee.

An instrument for adjusting the surfaces of work to the same inclination.

Bevel

An instrument for adjusting the surfaces of work to the same inclination.

"The part of the body in which the centre of gravity is situated, may be found, in some cases, by balancing it on a point. Thus the centre of gravity of the poker represented [here] lies directly over the point on which it is balanced." —Quackenbos 1859

Center of Gravity

"The part of the body in which the centre of gravity is situated, may be found, in some cases, by balancing…

"One of the best-known instruments of this [electrometer] class is Coulomb's torsion-balance, which consists essentially of gilt ball, i, carried at the end of a horizontal shellac needle that is suspended by a fine silver wire from the top of a tube that rises from the cover of the enclosing glass cylinder. A vertical insulating rod passing through the cover carries a handle, a, and a gilt ball, e, at its ends." -Avery 1895

Coulomb's Torsion-Balance

"One of the best-known instruments of this [electrometer] class is Coulomb's torsion-balance, which…

A small scale used for weighing silver, medicines, etc.

Dotchin

A small scale used for weighing silver, medicines, etc.

"The simplest way of measuring a force is to use a dynamometer, of which the spring-balance is a familiar example. The dynamometer may be graduated in pounds, grams, poundals, or dynes." — Avery, 1895

Dynamometer

"The simplest way of measuring a force is to use a dynamometer, of which the spring-balance is a familiar…

"When two forces counteract, or balance each other out, they are said to be in equilibrium." -Comstock 1850

Equilibrium

"When two forces counteract, or balance each other out, they are said to be in equilibrium." -Comstock…

An illustration of an African American slave who is employed as a field hand, notice the basket balancing on his head.

Field Hand

An illustration of an African American slave who is employed as a field hand, notice the basket balancing…

An illustration of a flea dressed in a uniform walking across a tight rope while holding a stick.

Flea Tight-Rope

An illustration of a flea dressed in a uniform walking across a tight rope while holding a stick.

A gimbals is a contrivance designed to keep a marine compass, chronometer, lamp, or other instrument in the horizontal position on board ship, notwithstanding the rolling and pitching of the vessel. The instrument is suspended in the diametral axis of a ring, which is again suspended in the diametral axis of another ring, the two axes being at right angles to one another.

Gimbals

A gimbals is a contrivance designed to keep a marine compass, chronometer, lamp, or other instrument…

A gimbals is a contrivance designed to keep a marine compass, chronometer, lamp, or other instrument in the horizontal position on board ship, notwithstanding the rolling and pitching of the vessel. The instrument is suspended in the diametral axis of a ring, which is again suspended in the diametral axis of another ring, the two axes being at right angles to one another. This illustration shows a diagram of a gimbals, showing the angle of the ship (A), the perpendicular axes of the rings, and the compass suspended horizontally in the gimbals (B).

Gimbals (Diagram)

A gimbals is a contrivance designed to keep a marine compass, chronometer, lamp, or other instrument…

A gimbals is a contrivance designed to keep a marine compass, chronometer, lamp, or other instrument in the horizontal position on board ship, notwithstanding the rolling and pitching of the vessel. The instrument is suspended in the diametral axis of a ring, which is again suspended in the diametral axis of another ring, the two axes being at right angles to one another. This illustration shows a gimbal joint.

Gimbals (Joint)

A gimbals is a contrivance designed to keep a marine compass, chronometer, lamp, or other instrument…

A scene from Hawthorne's "Grandfather's Chair." A young girl is on a large scale, being weighed for her portion in silver.

Grandfather's Chair

A scene from Hawthorne's "Grandfather's Chair." A young girl is on a large scale, being weighed for…

A card and coin balanced on one finger, with the other hand poised to flick it off.

Hands and Card

A card and coin balanced on one finger, with the other hand poised to flick it off.

"The connexions of all these six coils are such that when a current is passed through the whole of the coils in series, forces of attraction and repulsion are brought into existence which tend to force one movable coil upwards and the other movable coil downwards." —Encyclopedia Britannica, 1910

Connexions of Kelvin Ampere Balance

"The connexions of all these six coils are such that when a current is passed through the whole of the…

"The upper edge of the shelf on which the weights slide is graduated into equal divisions, and the weight is provided with a sharp tongue of metal in order that its posistion on the shelf may be accurately determined." —Encyclopedia Britannica, 1910

Slider of Kelvin Ampere Balance

"The upper edge of the shelf on which the weights slide is graduated into equal divisions, and the weight…

Illustration of an ordinary steel-yard being used as a lever. F represents the fulcrum. Weight P is used to balance weight W.

Steel-yard Used as a Lever

Illustration of an ordinary steel-yard being used as a lever. F represents the fulcrum. Weight P is…

"Diagram illustrating the muscles (drawn in thick black lines) which pass before and behind the joints and by their balanced activity keep the joints rigid and the body erect." —Martin, 1917

Muscle Diagram

"Diagram illustrating the muscles (drawn in thick black lines) which pass before and behind the joints…

"They carry everything on their heads." —Carpenter, 1902

Natives of Paraguay

"They carry everything on their heads." —Carpenter, 1902

"...let the area of the piston a be 1 square inch; of b, 40 square inches. According to Pascal's law, 1 pound placed on a will balance 40 pounds placed on b." —Hallock 1905

Pascal's Law and Water Pressure

"...let the area of the piston a be 1 square inch; of b, 40 square inches. According to Pascal's law,…

Illustration of a hydraulic machine. "A principle known as Pascal's Law states that pressure exerted on a liquid in a closed vessel is transmitted equally and undiminished in all directions." If a, A, p, and P respectively represent the areas and pressures, then the following proportion holds: a:A = p:P.

Hydraulic Machine Exerting Pressure

Illustration of a hydraulic machine. "A principle known as Pascal's Law states that pressure exerted…

A reefband crossing a sail diagonally.

Balance Reef

A reefband crossing a sail diagonally.

A rudder supported on a skeg or projection from the keel, about one third of its surface being forward and two thirds abaft its vertical axis.

Balance Rudder

A rudder supported on a skeg or projection from the keel, about one third of its surface being forward…

An instrument used to determine the weight of an object.

Scale

An instrument used to determine the weight of an object.

"A common scale-beam, used for weighing, is a lever, suspended at the centre of gravity, so that the two arms balance each other. Hence the machine is called a balance. The fulcrum, or what is called the pivot, is sharpended, like a wedge, and made of hardened steel, so as much as possible to avoid friction." -Comstock 1850

Scale

"A common scale-beam, used for weighing, is a lever, suspended at the centre of gravity, so that the…

An illustration of a lever scale.

Lever Scales

An illustration of a lever scale.

"A pracitcal application of a balance/lever is a see-saw." —Quackenbos 1859

See-saw

"A pracitcal application of a balance/lever is a see-saw." —Quackenbos 1859

Three spring-balances hooked together around a small ring.

Spring-balances

Three spring-balances hooked together around a small ring.

"The Steelyard is more portable then the ordinary balance. It consists of a lever, AB, moving round a knife-edge or point at C. The body to be weighed, W, is put into the scale which hangs from A; and a movable weight P, is made to slide along the longer arm, until the lever, AB, remains horizontal." — Chambers' Encyclopedia, 1875

Steelyard

"The Steelyard is more portable then the ordinary balance. It consists of a lever, AB, moving round…

"The steelyard differs from the balance, in having its support near one end, instead of in the middle, and also in having the weights suspended by hooks, instead of being placed in a dish." -Comstock 1850

Steelyard

"The steelyard differs from the balance, in having its support near one end, instead of in the middle,…

"When bodies of unequal weight are supported by the arms of a lever, they will balance each other whenever the weight of the one multiplied into its distance from the fulcrum." —Quackenbos 1859

Steelyard

"When bodies of unequal weight are supported by the arms of a lever, they will balance each other whenever…

"The steelyard is a kind of balance, which, though not so sensitive as the one being described above, answers very well for heavy bodies, and is conveniently carried, as it requires but a single weight, and may be held in the hand or suspended anywhere." —Quackenbos 1859

Steelyard

"The steelyard is a kind of balance, which, though not so sensitive as the one being described above,…

The steelyard is an instrument for weighing bodies by means of a single weight which can be hung at any point of a graduated arm.

Steelyard

The steelyard is an instrument for weighing bodies by means of a single weight which can be hung at…

"ABCD is a cylinder of glass 1 foot in diameter and 1 foot high. This cylinder is closed by a glass lid pierced centrically by two openings, each about 20 lines wide. Into the middle opening is cemented a glass tube 2 feet high, to the upper end of which is fitted a torsion head; the separate parts of the head are shown larger at the side of the figure. H is a collar cemented to the glass tube; MO a metal disc, divided on the edge into 360 degrees; this disc is fastened to a tube N, which slips into the collar H. K is a button whose neck turns easily in a hole in MO; to the lower part of the button is fastened a small clamp, which seizes the wire of the balance. I is an arm with a small projecting piece which slips over the edge of the disc MO." — Encyclopedia Britannica, 1893

Torsion Balance

"ABCD is a cylinder of glass 1 foot in diameter and 1 foot high. This cylinder is closed by a glass…

An illustration of an unequal-arm balance.

Unequal-arm Balance

An illustration of an unequal-arm balance.

"A loaded vehicle is represented as crossing the side of a hill, which has been raised one wheel above the level of the other wheel, so as to incline the body of the vehicle very considerably from the horizontal. The centre of gravity is represented in two different positions; a lower one with th eline of direction L C, and a higher one with the line of direction U C. If there had been no load upon the vehicle, the line of direction would have remained at L C; and as it falls within the wheel, or base, the vehicle would have maintained its balance. But if the wagon had been laden, the centre of gravity would have been raised, and, the line of direction U C consequently falling without the wheel, the vehicle must overturn." — Goodrich, 1844

Vehicle on hill

"A loaded vehicle is represented as crossing the side of a hill, which has been raised one wheel above…

"A cubic centimeter of water weighs 1 gram." — Avery, 1895

Water and scale

"A cubic centimeter of water weighs 1 gram." — Avery, 1895

An illustration of a price computing weighing machine using an even even balance and pendulum.

Price Computing Weighing Machine

An illustration of a price computing weighing machine using an even even balance and pendulum.

A weighing scale is a measuring instrument for determining the weight or mass of an object. A spring scale measures weight by the distance a spring deflects under its load. A balance compares the unknown weight to a standard weight using a horizontal lever.

Weighing Scale

A weighing scale is a measuring instrument for determining the weight or mass of an object. A spring…