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"Two cannon balls, when suspened by long cords, so as to hang quite near each other, are found to exert a mutual attaction, so that neither of the cords are excatly perpendicular, but they approach each other..." -Comstock 1850

Gravitational Attraction

"Two cannon balls, when suspened by long cords, so as to hang quite near each other, are found to exert…

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,…

"Why does a person carrying a weight upon his back stoop forward? In order to bring the center of gravity of his body and the load over his feet. If held in this position, he would fall backwards, as the direction of the center of gravity would fall beyond his heels." — Wells, 1857

Center of Gravity

"Why does a person carrying a weight upon his back stoop forward? In order to bring the center of gravity…

"Why does a person carrying a weight upon his back stoop forward? In order to bring the center of gravity of his body and the load over his feet, he assumes this position." — Wells, 1857

Center of Gravity

"Why does a person carrying a weight upon his back stoop forward? In order to bring the center of gravity…

"The center of gravity, in any body or system of bodies is that point upon which the body, or system of bodies, acted upn only by gravity will balance itself in all positions." -Comstock 1850

Center of Gravity

"The center of gravity, in any body or system of bodies is that point upon which the body, or system…

"But if one of the balls be heavier than the other, then the centre of gravity will, in proportion, approach the larger ball." -Comstock 1850

Center of Gravity

"But if one of the balls be heavier than the other, then the centre of gravity will, in proportion,…

"In a body of equal thickness, as a board, or a slab of marble, but otherwise of an irregular shape, the centre of gravity may be found by suspending it, first from one point, and then from another, and marking, by means of a plumb line, the perpendicular ranges from the point of suspension. the centre of gravity will be the point where these two lines cross each other." -Comstock 1850

Center of Gravity

"In a body of equal thickness, as a board, or a slab of marble, but otherwise of an irregular shape,…

"If w and W, fig. 3, be two bodies of known weight, their center of gravity will be at C." —Hallock 1905

Center of Gravity

"If w and W, fig. 3, be two bodies of known weight, their center of gravity will be at C." —Hallock…

"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…

"When such a surface is irregular in shape, suspend it at any point, so that it may move freely, and when it has come to rest, drop a plumb line from the point of suspension and mark its direction on the surface. Do the same at any other point, and the centre of gravity will lie where the two line intersect." —Quackenbos 1859

Center of Gravity

"When such a surface is irregular in shape, suspend it at any point, so that it may move freely, and…

"Where five blocks are placed in this position, the point of gravity is near the centre of the thrd block, and is within the base as shown by the plumb line. But on adding another block, the gravitation point falls beyond the base, and the whole will now fall by its own weight." -Comstock 1850

Center of Gravity of Standing Blocks

"Where five blocks are placed in this position, the point of gravity is near the centre of the thrd…

"Find the center of gravity of two of the bodies, as W1, and W4, in fig 4. Assume that the weight of both bodies is concentrated at C1, and find the center of gravity of this combined weight at C1, and the weight of W2; let it be at C2; then find the center of gravity of the combined weights of W1, W4, W2 (concentrated at C2), and W2; let it be at C; then C will be the center of gravity of the four bodies." —Hallock 1905

Compound Center of Gravity

"Find the center of gravity of two of the bodies, as W1, and W4, in fig 4. Assume that the weight of…

"A load of hay...upsets where one wheel rises by little above the other, because it is broader on the top than the distance of the wheels from each other; while a load of stone is very rarely turned over..." -Comstock 1850

Center of Gravity of a Load of Hay

"A load of hay...upsets where one wheel rises by little above the other, because it is broader on the…

"To find the center of gravity of any irregular plane figure, but of uniform thickness throughout, divide one of the parallel surfaces into triangles, parallelograms, circles, ellipses, etc., according to the shape of the figure; find the area and center of gravity of each part separately, and combine the center of gravity thus found in the same manner." —Hallock 1905

Center of Gravity of an Irregular Plane

"To find the center of gravity of any irregular plane figure, but of uniform thickness throughout, divide…

"When a line of direction falls within the base, a body stands when not, it falls... On the same principle, a load of stone may pass safely over a hillside, on which a load of hay would be overturned [as shown by the line of direction in this illustration]." —Quackenbos 1859

Line of Direction from the Center of Gravity of an Object

"When a line of direction falls within the base, a body stands when not, it falls... On the same principle,…

"When two bodies of equal weight are connected by a rod, the centre of gravity will lie in the middle of that rod. When two bodies of unequal weight are so connected, the centre of gravity will be nearer to the heavier one. These principles are illustrated [here], in which C represents the centre of gravity." —Quackenbos 1859

Center of Gravity of Rod with Weights

"When two bodies of equal weight are connected by a rod, the centre of gravity will lie in the middle…

"When a ball is rolling on a horizontal plane, the centre of gravity is not raised, but moves in a straight line, parallel to the surface of the plane on which it rolls, and is consequently always directly over its centre of gravity." -Comstock 1850

Center of Gravity of a Rolling Ball

"When a ball is rolling on a horizontal plane, the centre of gravity is not raised, but moves in a straight…

"In a body free to move, the center of gravity will lie in a vertical plumb-line drawn through the point of support. Therefore, to find the position of the center of gravity of an irregular solid, as the crank, Fig 8, suspended it at some point, as B, so that it will move freely. Drop a plumb line from the point of suspension and mark its direction. Suspend the body at another point, as A, and repeat the process. The intersection C of the two lines will be directly over the center of gravity." —Hallock 1905

Center of Gravity of a Solid

"In a body free to move, the center of gravity will lie in a vertical plumb-line drawn through the point…

"Daniel gravity cell, 'crowfoot' pattern. this is a two fluid cell in which gravity instead of a prous cup is depended upon to keep the liquids separate. The two solutions consist of copper sulphate and diluted sulphuric acid, the elements being made of zinc and copper." -Hawkins, 1917

Daniel Cell

"Daniel gravity cell, 'crowfoot' pattern. this is a two fluid cell in which gravity instead of a prous…

A fault is a planar fracture in rock in which the rock on one side of the fracture has moved with respect to the rock on the other side. Here, the arrow indicates the downthrow side.

Gravity Fault

A fault is a planar fracture in rock in which the rock on one side of the fracture has moved with respect…

A fault is a planar fracture in rock in which the rock on one side of the fracture has moved with respect to the rock on the other side. Here, the arrow indicates the downthrow side.

Gravity Fault

A fault is a planar fracture in rock in which the rock on one side of the fracture has moved with respect…

A fault is a planar fracture in rock in which the rock on one side of the fracture has moved with respect to the rock on the other side. Here, the arrow indicates the downthrow side.

Gravity Fault

A fault is a planar fracture in rock in which the rock on one side of the fracture has moved with respect…

A fault is a planar fracture in rock in which the rock on one side of the fracture has moved with respect to the rock on the other side. Here, the arrow indicates the downthrow side.

Gravity Fault

A fault is a planar fracture in rock in which the rock on one side of the fracture has moved with respect…

A fault is a planar fracture in rock in which the rock on one side of the fracture has moved with respect to the rock on the other side. Here, the arrow indicates the downthrow side.

Gravity Fault

A fault is a planar fracture in rock in which the rock on one side of the fracture has moved with respect…

"The electric resistance of the porous cup employed in the Daniel cell, and the local action produced by the material of which is it composed, led to the invention of similar cells in which it is dispensed with, the gravity cell." --Atkinson 1903

Gravity Cell

"The electric resistance of the porous cup employed in the Daniel cell, and the local action produced…

"E represents the scape-wheel turning in a minute, and e its pinion, which is driven by the wheel D having a pinion d driven by the wheel C, which we may suppose to turn in an hour. The arbors of the scape-wheel and hour-wheel are distinct, their pivots-meeting in a bush fixed somewhere between the wheels. The pivots of the wheel, D are set in the frame AP, which rides on the arbors of the hour-wheel and scape-wheel, or on another short arbor between them. The hour-wheel also drives another wheel G, which again drives the pinion f on the arbor which carries the two arms f A, f B; and on the same arbor is set a fly with a ratchet, like a common striking fly, and the numbers of the teeth are so arranged that the fly will turn once for each turn of the scapewheel. The ends of the remontoire arms f A, f B are capable of alternately passing the notches cut half through the arbor of the scape-wheel, as those notches successively come into the proper position at the end of every half minute; as soon as that happens the-hour-wheel raises the movable wheel D and its frame through a small angle; but nevertheless, that wheel keeps pressing on the scape-wheel as if it were not moving, the point of contact of the wheel C and the pinion d being the fulcrum or center of motion of the level A d P." — Encyclopedia Britanica, 1893

Gravity Train Remontoire

"E represents the scape-wheel turning in a minute, and e its pinion, which is driven by the wheel D…

"That the cannon ball is capable of attracting as well as being attracted, may be proved by suspending two balls close to each other by very long cords. In consequence of their attraction, the cords will not hang parallel, but will incline towards each other as they descend...." —Quackenbos 1859

Gravity Proved by Cannon Balls

"That the cannon ball is capable of attracting as well as being attracted, may be proved by suspending…

(1.) The guillotine is an instrument employed for the purpose of decapitation. It was officially introduced into France as the means of inflicting capital punishment in April, 1792. It was named after its reputed inventor, Dr. Joseph Ingace-Guillotin, who, contrary to popular belief, died a natural death, and not a victim of his own invention. The instrument consists of two upright posts held together at the top by a cross beam, the former being perpendicularly so grooved as to allow of the falling in a direct line a broad steel blade, whose edge is cut obliquely. The latter, sometimes weighted with lead, descends upon the neck of the criminal immediately after the cord which holds it up is released by the executioner. (2.) A guillotine is a machine, similar in name and in general construction to the above, employed by bookbinders. It is used for cutting paper and trimming the edges of books after the sheets have been sewn together.

Guillotine

(1.) The guillotine is an instrument employed for the purpose of decapitation. It was officially introduced…

"The Gyroscope is an instrument constructed by M. Foucault to make the rotation of the earth visible. The principle on which it proceeds is this– that, unless gravity intervene, a rotating body will not alter the direction in which its permanent axis points. In the gyroscope there is a rotating metallic disk, the middle point of whose axis is also the center of gravity of the machine. By this device the action of gravity is eliminated."—(Charles Leonard-Stuart, 1911)

Gyroscope

"The Gyroscope is an instrument constructed by M. Foucault to make the rotation of the earth visible.…

"The principle of increased velocity as bodies descend from a height, is curiously illustrated by pouring molasses or thick syrup from an elevation to the ground. The bulky stream, of perhaps two inches in diameter where it leaves the vessel, as it descends, is reduced to the size of a straw, or knitting-needle; but what it wants in bulk is made up in velocity, for the small stream at the ground will fill a vessel just as soon as the large one at the outlet." —Comstock, 1850

Increased Velocity

"The principle of increased velocity as bodies descend from a height, is curiously illustrated by pouring…

"Knight's experiment, substituting centrifugal "force" for gravity" proved that stems do not grow upwards because of sunlight but rather, roots grow downwards because of gravity. -Gager, 1916

Knight's Experiment

"Knight's experiment, substituting centrifugal "force" for gravity" proved that stems do not grow upwards…

"Galactometer. A species of hydrometer for determining the richness of milk by its specific gravity." -Whitney, 1911

Lactometer

"Galactometer. A species of hydrometer for determining the richness of milk by its specific gravity."…

An illustration of Sir Isaac Newton sitting on the ground being hit by an apple falling out of a tree and discovering the law of gravity.

Isaac Newton Discovering Gravity

An illustration of Sir Isaac Newton sitting on the ground being hit by an apple falling out of a tree…

The death mask of Sir Isaac Newton, who discovered the law of gravitation.

Death Mask of Sir Isaac Newton

The death mask of Sir Isaac Newton, who discovered the law of gravitation.

(1642-1727) English natural philosopher, mathematician, and physicist most famous for gravity and his laws of motion.

Sir Isaac Newton

(1642-1727) English natural philosopher, mathematician, and physicist most famous for gravity and his…

"Partz acid gravity cell. In this form of cell, the electrolyte which surrounds the zinc is either magnesium sulphate or common salt. the depolarizer is a bichromate silution which surounds the perforated carbon plate located in the bottom of the jar. A vertical carbon rod fits snugly into the tapered hole in the carbon plate, and extends through the cover forming the positive pole." -Hawkins, 1917

Partz Cell

"Partz acid gravity cell. In this form of cell, the electrolyte which surrounds the zinc is either magnesium…

"When the pendulum is drawn from its vertical position, the force of gravity, MG, is resolved into two components, one of which, MC, produces pressure at the point of support, while the other, MH, acts at right angles to it, producing motion toward N." -Avery 1895

Motion of a Pendulum

"When the pendulum is drawn from its vertical position, the force of gravity, MG, is resolved into two…

"[This illustration] shows the path of a stone thrown obliquely from the hand. The propelling force sends it in a straight line to A, and would take it on in the same direction to B, were it not that, as soon as its velocity becomes sufficiently diminished, gravity and the air's resistance give it a circular motion to C, and finally bring it to the earth at D." —Quackenbos 1859

Projectile Motion of a Stone

"[This illustration] shows the path of a stone thrown obliquely from the hand. The propelling force…

Sprengel's pynkometer, a u-shaped flask.

Sprengel's pyknometer

Sprengel's pynkometer, a u-shaped flask.

"A glass vessel used to separate liquids which differ in specific gravity and are not miscible." -Whitney, 1911

Separator

"A glass vessel used to separate liquids which differ in specific gravity and are not miscible." -Whitney,…

A device used for measuring the specific gravity of an object or substance.

Specific gravity bottle

A device used for measuring the specific gravity of an object or substance.

One of the commonest ways of determining the density of a solid body is to weight it first in air and then in water.

Specific Gravity of Solids

One of the commonest ways of determining the density of a solid body is to weight it first in air and…

"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…

"If a vessel be filled with water, and three apertures be made in its sie at E F G, the fluid will be thrown out in jets, falling to the earth in the curved lines shown." -Comstock 1850

Water Velocity and Gravity

"If a vessel be filled with water, and three apertures be made in its sie at E F G, the fluid will be…