Diagram of the muscles of the arm in action. Labels: 1, humerus; 2, ulna, 3, biceps muscle; 4, attachment to the humerus; 6, triceps muscle; 7, tendon; 8, a ball to be moved. 9, 10, 11, direction the ulna moves when the biceps muscle contracts. When the triceps muscle contracts, the forearm extends.

Arm Muscles in Action

Diagram of the muscles of the arm in action. Labels: 1, humerus; 2, ulna, 3, biceps muscle; 4, attachment…

"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…

A tool used for boring holes in metal, stone, wood, or an other hard substance.

Drill Bit

A tool used for boring holes in metal, stone, wood, or an other hard substance.

A bridge which may be drawn up or let down to admit or hinder communication, or to leave a transverse passage free.

Draw Bridge

A bridge which may be drawn up or let down to admit or hinder communication, or to leave a transverse…

"The capstan, in universal use, on board of ships, is an axle placed upright, with a head, or drum, A, pierced with holes for the levers B, C, D. The weight is drawn by the rope E, passing two or three times round the axle to prevent its slipping. This is a very powerful and convenient machine. When not in use, the levers are taken out of their places and laid aside, and when great force is required two or three men can push at each lever." —Comstock, 1850

Capstan

"The capstan, in universal use, on board of ships, is an axle placed upright, with a head, or drum,…

"Central-fire Gun. C, central-fire cartridge; L, lever; W, washer; S, screw." — Encyclopedia Britannica, 1893

Central-fire Gun

"Central-fire Gun. C, central-fire cartridge; L, lever; W, washer; S, screw." — Encyclopedia Britannica,…

"The common chipping-knife, used by apothecaries, and represented [here], is a familiar illustration of levers of the second kind [class]." —Quackenbos 1859

Chipping Knife

"The common chipping-knife, used by apothecaries, and represented [here], is a familiar illustration…

"When several simple levers are connected together, and act one upon the other, the machine is called a compound lever." -Comstock 1850

Compound Lever

"When several simple levers are connected together, and act one upon the other, the machine is called…

"In compound levers, equilibrium is established when the power, multiplied by the first arms of all the levers, is equal to the weight multiplied by the last arms of all the levers." —Quackenbos 1859

Compound Lever

"In compound levers, equilibrium is established when the power, multiplied by the first arms of all…

A crane in which the postis supported by fixed stays in the rear and the jib is pivoted like the boom of a derrick.

Derrick Crane

A crane in which the postis supported by fixed stays in the rear and the jib is pivoted like the boom…

"... shows one of the commonest (sic) forms in which this kind of lever appears,-the crowbar. The power is applied at the handle. The weight is at the other end, and consists of something to be moved. The fulcrum is a stone on which the crowbar rests." —Quackenbos 1859

Crowbar

"... shows one of the commonest (sic) forms in which this kind of lever appears,-the crowbar. The power…

"... a farmer with a crowbar, as shown, can move a rock which with his hands alone he could not stir." —Quackenbos 1859

Crowbar and Stone

"... a farmer with a crowbar, as shown, can move a rock which with his hands alone he could not stir."…

An Iron Age horse cultivator, good for working crops which require a horse cultivator. The levers can make the frame wider or narrower, enabling it to be used to create rows of the desired width.

Iron Age horse cultivator

An Iron Age horse cultivator, good for working crops which require a horse cultivator. The levers can…

"The plate A is 46 inches in diameter, and is composed of gun metal. These were put on by original graduation, mainly on the plan of Edward Troughton. One very great improvement in this engine is that the axis B is tubular, as seen at C. The object of this hollow is to receive the axis of the circle to be divided, so that it can be fixed flat to the plate by the clamps E, without having first to be detached from the axis and other parts to which it has already been carefully fitted. This obviates the necessity for resetting, which can hardly be done without some error. D is the tangent screw, and F the flame carrying it, which turns on carefully polished steel pivots. The screw is pressed against the edge of the plate by a spiral spring acting under the lever G, and by screwing the lever down the screw can be altogether removed from contact with the plate." — Encyclopedia Britannica, 1893

Dividing Engine

"The plate A is 46 inches in diameter, and is composed of gun metal. These were put on by original graduation,…

A lever of the first class

First Class Lever

A lever of the first class

"A lever is an inflexible bar freely movable about a fixed axis called the fulcrum. If the fulcrum is between the power and weight, the lever is of the first class." — Avery, 1895

First Class Lever

"A lever is an inflexible bar freely movable about a fixed axis called the fulcrum. If the fulcrum is…

"First class lever." -Comstock 1850

First class lever

"First class lever." -Comstock 1850

"A Lever of the First Kind is one in which the fulcrum is between the power and the weight... where F represents the fulcrum, P the power, and W the weight." —Quackenbos 1859

First Class Lever

"A Lever of the First Kind is one in which the fulcrum is between the power and the weight... where…

In the first order of levers, the fulcrum is between the power and the weight.

First Orders of Lever

In the first order of levers, the fulcrum is between the power and the weight.

"First class lever." -Comstock 1850

First-class Lever

"First class lever." -Comstock 1850

"In mechanics, the point of rest about which a lever turns in lifting a body; also, a prop or support for a lever at this point. F, Fulcrum; L, lever." -Whitney, 1911

Man with Lever and Fulcrum

"In mechanics, the point of rest about which a lever turns in lifting a body; also, a prop or support…

"Shot-pouches. A, pouch for one size of shot: a, pouch; b, charger with gates c, c'; d, spring which holds the gate c closed until the lever e, which shuts the gate c' and opens c, is depressed, when the charge filling the nozzle between the two gates is released. The charge can be lessened by placing the gate c in the slot f." -Whitney, 1911

Hunting Shot Pouch

"Shot-pouches. A, pouch for one size of shot: a, pouch; b, charger with gates c, c'; d, spring which…

"Shot-pouches. ... B, pouch (shot-belt) for two sizes of shot: a, a', pouches; b, strap for attachment to the person of the sportsman; c, c', nozzles, each with a single spring gate. The charge is measured in the detachable charger d." -Whitney, 1911

Hunting Shot Pouch

"Shot-pouches. ... B, pouch (shot-belt) for two sizes of shot: a, a', pouches; b, strap for attachment…

A device for connecting wires from a battery.

Du Bois-Reymond's Key

A device for connecting wires from a battery.

A key used to connect wires from a battery using mercury.

Mercury Key

A key used to connect wires from a battery using mercury.

"The engraving shows a large, powerful man, of giant size and strength, endeavoring to move a large stone, or rock, which obstructs a passage way. His brute force is, however, unavailing, as with all his great strength he cannot move the stone one inch. But see the superiority of head work, or wisdom. A small, weak man approaches: he has not got half the bodily strength of his companion, but he has a larger and more powerful mind, and by it he can do what the other cannot; he can lift a weight which the other cannot move. His wisdom teaches him the power of the lever, and by one arm he can move a house, showing that 'Knowledge is Power.'"—Barber, 1857

Knowledge is Power

"The engraving shows a large, powerful man, of giant size and strength, endeavoring to move a large…

"In mechanics, the word 'machine' signifies an instrument for the conversion of motion or the transference of energy." -Avery 1895

Man Using Lever and Fulcrum to Lift Rock

"In mechanics, the word 'machine' signifies an instrument for the conversion of motion or the transference…

"The object W to be lifted is called the weight; the force is represented by P; the point, or pivot, F is called the fulcrum." —Hallock 1905

Lever

"The object W to be lifted is called the weight; the force is represented by P; the point, or pivot,…

"The object W to be lifted is called the weight; the force is represented by P; the point, or pivot, F is called the fulcrum." —Hallock 1905

Lever

"The object W to be lifted is called the weight; the force is represented by P; the point, or pivot,…

"The object W to be lifted is called the weight; the force is represented by P; the point, or pivot, F is called the fulcrum." —Hallock 1905

Lever

"The object W to be lifted is called the weight; the force is represented by P; the point, or pivot,…

Illustration of a lever with fulcrum F. W represents the weight lifted, P is the force that does the lifting, D is the distance from the fulcrum to the point of application of the force, and d is the distance from the fulcrum to the point where the weight is attached. In all possible relations of the fulcrum, weight, and force the following proportion holds: P:W = d:D.

Lever and Fulcrum

Illustration of a lever with fulcrum F. W represents the weight lifted, P is the force that does the…

Lever of the first class.

Lever of the first class

Lever of the first class.

Lever of the second class.

Lever of the second class

Lever of the second class.

Lever of the third class.

Lever of the third class

Lever of the third class.

An illustration of a lever with weights m and n with distances a and b from fulcrum. Illustration could be used with proportions.

Lever Balanced on fulcrum With Weights

An illustration of a lever with weights m and n with distances a and b from fulcrum. Illustration could…

"Sometimes it is not convienent to use a lever sufficiently long to make a given power support a given weight. A combination of levers, called a compound lever, may then be used." -Avery 1895

Compound Lever

"Sometimes it is not convienent to use a lever sufficiently long to make a given power support a given…

"In straight levers of the first kind, the fulcrum is between the power and the resistance, as in fig 1, where F is the fulcrum of the lever AB; P is the power, and W the weight or resistance."—Pettigrew, 1874

First Kind of Lever

"In straight levers of the first kind, the fulcrum is between the power and the resistance, as in fig…

Illustration of a hammer being used as a lever. F represents the fulcrum.

Hammer Used as a Lever

Illustration of a hammer being used as a lever. F represents the fulcrum.

"In the second order of levers, the resistance is between the fulcrum and the power; and, as before, P : W :: BF : AF, but the pressure of the fulcrum is equal to W-P, or the weight less the power."—Pettigrew, 1874

Second Kind of Lever

"In the second order of levers, the resistance is between the fulcrum and the power; and, as before,…

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…

"In the third order of lever the power acts between the prop and the resistance, where also P : W :: BF : AF, and the pressure on the fulcrum is P-W, or the power less the weight."——Pettigrew, 1874

Third Kind of Lever

"In the third order of lever the power acts between the prop and the resistance, where also P : W ::…

Each of these are an example of the simple machine: lever. F c is the power arm and F w is the weight arm. W is the weight and P is power

Simple Machines

Each of these are an example of the simple machine: lever. F c is the power arm and F w is the weight…

"Morse magnetic telegraph will be understood by reference to the accompanying diagram, which represents the construction and arrangement of this form of telegraph. F and E are pieces of soft iron surrounded by coils of wire, which are connected at a and b with wires proceeding from a galvanic battery. When a current is transmitted from a battery located one, two, or three hundred miles, as the case may be, it passes along the wires and into the coils surrounding the pieces of soft iron F and E, thereby converting them into magnets. Above these pieces of soft iron is a metallic bar or lever, A, supported on its center, and haing at one end the arm D, and at the other a small steel point, o. A ribbon of paper, p h, rolled on the cylinder B, is drawn slowly and steadily off by a train of clock-work, K, moved by the action of the weight P on the cord C. This clock-work gives motion to two metal rollers, G and H, between which the ribbon of paper passes, and which, turnin in opposite directions, draw the paper from the cylinder B. The roller H has a groove arond its circumference (not represented in the engraving) above which the paper passes. The steel point, r, or the lever, A, is also directly opposite this groove. The spring r prevents the point from resting upon the paper when the telegraph is not in operation." —Wells, 1857

Magnetic Telegraph

"Morse magnetic telegraph will be understood by reference to the accompanying diagram, which represents…

The lever pressed by the finger to discharge a firearm.

Trigger Mechanism

The lever pressed by the finger to discharge a firearm.

"Pascal's law finds an important application in the hydraulic press, in the more common forms of which the pressure of a piston operated by a lever is transmitted though a pipe to a piston of larger area." — Avery, 1895

Hydraulic press

"Pascal's law finds an important application in the hydraulic press, in the more common forms of which…

A hydraulic press is a hydraulic mechanism for applying a large lifting or compressive force. It is the hydraulic equivalent of a mechanical lever, and is also known as a Bramah press after the inventor, Joseph Bramah, of England. He invented and was issued a patent on this press in 1795. Hydraulic presses are the most commonly-used and efficient form of modern press.

Hydraulic Press

A hydraulic press is a hydraulic mechanism for applying a large lifting or compressive force. It is…

A hydraulic press is a hydraulic mechanism for applying a large lifting or compressive force. It is the hydraulic equivalent of a mechanical lever, and is also known as a Bramah press after the inventor, Joseph Bramah, of England. He invented and was issued a patent on this press in 1795. Hydraulic presses are the most commonly-used and efficient form of modern press.

Hydraulic Press

A hydraulic press is a hydraulic mechanism for applying a large lifting or compressive force. It is…

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…

"In the single fixed pulley (fig. 1) there is no mechanical advantage, the power and weight being equal. It may be considered as a lever of the first kind with equal arms. In the single movable pulley (fig. 2) where the cords are parallel there is a mechanical advantage, there being an equilibrium when the power is considered as a lever of the second kind, in which the distance of the power from the fulcrum is double hat of the weight from the fulcrum." -Marshall

Pulley

"In the single fixed pulley (fig. 1) there is no mechanical advantage, the power and weight being equal.…

"In a system of pulleys (figs. 3,4) in which the same string passes round any number of pulleys, and the parts of it between the pulleys are parallel, there is an equilibrium when the power is to the weight as 1 to the number of strings at the lower block" -Marshall

Pulley

"In a system of pulleys (figs. 3,4) in which the same string passes round any number of pulleys, and…

"In a system in which each pulley hangs by a separate cord and the strings are parallel (fig. 5), there is an equilibrium when the power is to the weight as 11 to that power of 2 whose index is the number of movable pulleys." -Marshall

Pulley

"In a system in which each pulley hangs by a separate cord and the strings are parallel (fig. 5), there…

A safety-valve, in which a weight is employed. Here a is the valve, b b the boiler, c c the valve-seat, usually, like the valve itself, made of gunmetal, d the lever turning upon a fixed center at e, and pressing upon the valve by a steel point f, a guide for the lever g a weight which may be shifted backwards and forwards according to the pressure desired.

Lever Safety-valve

A safety-valve, in which a weight is employed. Here a is the valve, b b the boiler, c c the valve-seat,…

"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.

"Many instruments in common use are on the principle of this kind of lever. Scissors, consists of two levers, the rivet being the fulcrum for both. The fingers are the power, and the cloth to be cut, the resistance to be overcome." -Comstock 1850

Scissors

"Many instruments in common use are on the principle of this kind of lever. Scissors, consists of two…

"In this, the screw is fixed, while the nut, N, by being turned by the lever, L, from right to left, will advance down the screw." -Comstock 1850

Screw Fixed Screw

"In this, the screw is fixed, while the nut, N, by being turned by the lever, L, from right to left,…

"The power is generally applied by a wheel or a lever, and moves through the circumfrence of a circle. The distance between the two consecutive turns of any on continuous thread, measured in the direction of the axis of the screw, is called the pitch of the screw." -Avery 1895

Screw with Lever Arm

"The power is generally applied by a wheel or a lever, and moves through the circumfrence of a circle.…

Compound screws commonly used as clamps.

Compound Screw

Compound screws commonly used as clamps.