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"Lines of force in a circular loop. If the loop pass through a piece of cardboard at right angles to its plane, and the curent flow as indicated, the dotted lines on the cardboard will represent the direction of the lines of force in the plane of the cardboard." -Hawkins, 1917

Lines of Force

"Lines of force in a circular loop. If the loop pass through a piece of cardboard at right angles to…

"Experiment illustrating the molecular theory of magnetism. Coarse steel filings are placed inside a small glass tube and the contents magnetized. It will be found that filing which at first had no definite arrangement will rearrange themselves under the influence of magnetic force, and assume symmetrical position, each one lying in line with, or parallel to its neighbor, as shown in the lower figure." -Hawkins, 1917

Magnetism

"Experiment illustrating the molecular theory of magnetism. Coarse steel filings are placed inside a…

Subcutaneous areolar tissue from a young rabbit, highly magnified. The white fibers are in wavy bundles, the elastic fibers form an open network. Labels: p, p, vacuolated cells; g, granular cells; c, c, branching lamellar cells; c', a flattened cells, of which only the nucleus and some scattered granules are visible; f, fibrillated cell. "If we make a cut through the skin of some part of the body where there is no subcutaneous fat, as in the upper eyelid, and proceed to raise it from the parts lying beneath, we observe that it is loosely connected to them by a soft filmy substance of considerable tenacity and elasticity. This is areolar tissue. It is also found, in like manner, under the serous and mucous membranes, and serves to attach them to the parts which they line or cover. Proceeding further, we find this areolar tissue lying between the muscles, the blood-vessels, and other deep-seated parts; also forming investing sheaths for the muscles, the nerves, the blood-vessels, and other parts. It both connects and insulates entire organs, and, in addition, performs the same office for the finer parts of which these organs are made up. It is thus one of the most general and most extensively distributed of the tissues." —Kimber, 1907

Subcutaneous Areolar Tissue from a Young Rabbit

Subcutaneous areolar tissue from a young rabbit, highly magnified. The white fibers are in wavy bundles,…

"Suppose a, b, to be a marble floor, and c, to be an ivory ball, which has be thrown towards the floor in the direction of the line c e; it will rebound in the direction of the line e d, thus making the two angles f and g exactly equal." -Comstock 1850

Reflected Motion

"Suppose a, b, to be a marble floor, and c, to be an ivory ball, which has be thrown towards the floor…

"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,…

"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…

"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…

"To change the direction, it is only necessary that the rope by which the weight is to be raised, should be carried in a line perpendicular to the axis of the machine, sto the place below where the weight lies, and there be let fall over a pulley." -Comstock 1850

Wheel and Axle

"To change the direction, it is only necessary that the rope by which the weight is to be raised, should…

"Although a ray of light will pass in a straight line, when not interrupted, yet when it passes obliquely from one transparent body into another, of a different density, it leaves its linear direction, and is bent, or refracted more or less, out of its former course." -Comstock 1850

Refraction of Light

"Although a ray of light will pass in a straight line, when not interrupted, yet when it passes obliquely…

"Let the medium b be glass, and the medium c, water. The ray a, as it falls upon the medium b, is refracted towards the perpendicular line e d; but when it enters the water, whose refractive power is less than that of glass, it is not bent so near the perpendicular as before, and hence it is refracted from, instead of towards the perpendicular line, and approaches the originial direction of the ray a g, when passing through the air." -Comstock 1850

Refraction, glass and water

"Let the medium b be glass, and the medium c, water. The ray a, as it falls upon the medium b, is refracted…

"Let a ray pass towards a mirror in the line a, c, it will be reflected off in the direction of c, d, making the angles 1 and 2 exactly equal." -Comstock 1850

Reflecion of Light

"Let a ray pass towards a mirror in the line a, c, it will be reflected off in the direction of c, d,…

"The ray a, c, is the ray of incidence, and that from c, to d, is the ray or reflection. The angles which a, c, make with the perpendicular line, and with the plane of the mirror, is exactly equal to those made by c, d, with the same perpendicular, and the same plane surface." -Comstock 1850

Reflection of Light

"The ray a, c, is the ray of incidence, and that from c, to d, is the ray or reflection. The angles…

"This will be understood [here] where the ray of light A B, proceeding from the eye, falls perpendicularly on the plane mirror B D. will be reflected back in the same line; but the ray C D coming from the feet, which falls obliquely on the mirror, will be reflected back under the same angle in the line D A; and since we see objects in the direction of the reflected rays, and the image appears at the same distance behind the mirror that is object is before it, we must continue the line A D to the feet, E, and for the same reason, the rays A B, from the eye, must be prolonged to F, as far behind the mirror as the line E extends, where the whole image will be represented." -Comstock 1850

Mirror Half the Length of the Object

"This will be understood [here] where the ray of light A B, proceeding from the eye, falls perpendicularly…

"...if the object is placed more remote from the mirror than the principal focus, and between the focus and the centre of the sphere of which the reflector is a part, then the image will appear inverted on the contrary side of the centre, and farter from the mirror than the object; thus, if a lamp be placed obliquely before a concave mirror, its image will be seem inverted in the air, on the contrary side of a perpendicular line through the centre of the mirror." -Comstock 1850

Object Beyond the Focus in a Concave Mirror

"...if the object is placed more remote from the mirror than the principal focus, and between the focus…

The skeleton of the trunk and the limb arches seen from the front. Labels: c, clavicle; S, scapula; Oc, innominate bone attached to the side of the sacrum dorsally and meeting its fellow at the pubic symphysis in the ventral median line.

Skeleton of Trunk

The skeleton of the trunk and the limb arches seen from the front. Labels: c, clavicle; S, scapula;…

"Let any irregularly shpaed body, as a stone or chair, be suspended so as to move freely. Drop a plumb line from the point of the suspendsion, and make it fast or mark its direction. The center of mass will lie in this line. From a second point, not in the line already determined, suspend the body; let it fall a plumb line as before. The center of mass will lie in this line also. But to lie in both lines, it must lie at their intersection." -Avery 1895

Finding the Center of Mass

"Let any irregularly shpaed body, as a stone or chair, be suspended so as to move freely. Drop a plumb…

"The Nicholson hydrometer of constant volume is a hollow cylinder carrying at its lower end a basket, d, heavy enough to keep the apparatus upright in water. At the top of the cylinder is a vertical rod carrying a pan, a, for holding weights, etc. The whole apparatus must be lighter than water, so that a certain weight (W) must be put into the pan to sink the apparatus to a fixed point marked on the rod (as c). The given body, which must weigh less than W, is placed in the pan, and enought weights (w) added to sink the point c, to the water line It is evident that the weight of the given body is W-w." -Avery 1895

Nicholson Hydrometer

"The Nicholson hydrometer of constant volume is a hollow cylinder carrying at its lower end a basket,…

"Tie one end of a soft cotton rope about 20 feet long to a fixed support, and hold the other end in the hand. Move the hand up and down with a quick, sudden motion, so as to set up a series of waves in the rope, as shown, in which each curved line may be considered an instantaneous photograph of a rope thus shaken." -Avery 1895

Form of Waves

"Tie one end of a soft cotton rope about 20 feet long to a fixed support, and hold the other end in…

"Fill with carbon dioxide a large rubber toy balloon or other double-convex lens having easily flexible walls. Suspend a watch, and place yourself so that you can just hear its ticking. Have the gas-filled lens moved back and forth in the line between watch and and ear until the ticking is much more plainly heard. Use a glass funnel as an ear-trumpet." -Avery 1895

Sound Refraction

"Fill with carbon dioxide a large rubber toy balloon or other double-convex lens having easily flexible…

"Consider a beam of light as made up of a number of ehter waves moving forward in air and side by side, as represented by the rays A, B, C. Imagine a plane, MN, normal to these yars, attached to the waves and moving forward in a straight line. As the wave front advances beyond MN, the ray, A, strikes the reflecting surface, RS, and is turned back into the air in accordance with the law just given." -Avery 1895

Explanation of Reflection

"Consider a beam of light as made up of a number of ehter waves moving forward in air and side by side,…

"Thus, when erher waves that constitute light are transmitted through glass, they are hindered by the molecules of the glass, and impart some of their motion to those molecules' i.e., a part of the light is absorbed. When a beam of light, as represented by ABC moves forward in the air, the wave-front, MN, continues parallel to itself and moves forward in a straight line. As the wave front advances, A strikes the glass first, and is retarted, the retardation of B and C later change the direction of the rays." -Avery 1895

Explanation of Refraction

"Thus, when erher waves that constitute light are transmitted through glass, they are hindered by the…

"The double convex lens may be described as the part common to two spheres that intersect each other. The centers of the limiting spherical surfaces, as c and C, are the centers of curvature. The straight line, XY, passing through the centers of curvature is the principal axis of the lens." -Avery 1895

Double Convex Lens

"The double convex lens may be described as the part common to two spheres that intersect each other.…

"An electric bell consists mainly of an electromagnet, E, and a vibrating armature that carries a hammer, H, that strikes a bell. One terminal of the magnet coils is connected to the binding-post, and the other terminal to the flexible support of the armature. The armature carries a spring that rests lightly against the tip of an adjustable screw at C. This screw is connected to the other binding-post. The bell is connected to a battery of 2 or 3 cells in series, a key, a push-button, P, or some other device for closing the circuit being placed in the line." -Avery 1895

Electric Bell

"An electric bell consists mainly of an electromagnet, E, and a vibrating armature that carries a hammer,…

"A transmitter or key is a current interrupter manipulated by the operator. It consists essentially of a metal layer, L, pivoted at aa, and conneted to the line by the screw at m which is insultated from the base, and the screw at n which is connected to the base and lever." -Avery 1895

Telegraph Transmitter

"A transmitter or key is a current interrupter manipulated by the operator. It consists essentially…

"With a long main-line and many instruments in circuit, the resistance may be so great as to render the main-battery current so feeble that it cannot operate the sounder with sufficient energy to render the signals distinctly audible. This difficulty is met by introducing a 'local battery,' and a 'relay' at each station on the line." -Avery 1895

Telegraph Relay

"With a long main-line and many instruments in circuit, the resistance may be so great as to render…

"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…

"If a body be fastened to a string and whirled, so as to give it a circular motion, there will be a pull on the string that will be greater or less according as the velocity increases or decreases... If the string were cut, the pulling force that drew it away from the straight line would be removed, and the body would then fly off at a tangent; that is, it would move in a straight line tangent to the circle, as shown in Fig. 9." —Hallock 1905

Centrifugal Force

"If a body be fastened to a string and whirled, so as to give it a circular motion, there will be a…

"An inclined plane is a slope, or flat surface, making an angle with a horizontal line...the force acts parallel to the plane." —Hallock 1905

Inclined Plane with the Force Acting Parallel to the Plane

"An inclined plane is a slope, or flat surface, making an angle with a horizontal line...the force acts…

"An inclined plane is a slope, or flat surface, making an angle with a horizontal line...the force acts parallel to the base." —Hallock 1905

Inclined Plane with the Force Acting Parallel to the Base

"An inclined plane is a slope, or flat surface, making an angle with a horizontal line...the force acts…

"An inclined plane is a slope, or a flat surface, making an angle with a horizontal line...the force acts at an angle to the plane or to the base." —Hallock 1905

Inclined Plane with Force at an Angle to Plane and Base

"An inclined plane is a slope, or a flat surface, making an angle with a horizontal line...the force…

"Path of current through person receiving a shock from the fame of a machine insulated from ground. (There is an accidental tree ground on the line and a accidental ground in the winding of the machine.)." —Croft 1920

Electric Shock

"Path of current through person receiving a shock from the fame of a machine insulated from ground.…

"So a hare, in making for cover, often escapes a hound by making a number of quick turns. The greater inertia of the hound carries him to far, and thus obliges him to pass over a greater space, as seen [here], in which the continuous line shows the hare's path and the dotted line the hound's." —Quackenbos 1859

Inertia Demonstration

"So a hare, in making for cover, often escapes a hound by making a number of quick turns. The greater…

"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…

"Attach a ball, for instance, to a cord; and , fastening the end of the cord at a point, O, give a quick impulse to the ball. It will be found to move in a circle, ABCD, because the cord keeps it within a certain distance of the centre (sic). Were it not for this, it would move in a straight line." —Quackenbos 1859

Centrifugal Force

"Attach a ball, for instance, to a cord; and , fastening the end of the cord at a point, O, give a quick…

"... if a ball be thrown from F against the surface B C so as to strike it perpendicularly at A, it will return in the line A F. If thrown from D however, it will glance off on the other side of the perpendicular, at the same angle, to E." —Quackenbos 1859

Reflected Motion

"... if a ball be thrown from F against the surface B C so as to strike it perpendicularly at A, it…

"[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…

"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…

"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,…

Straight line

Straight Line

Straight line

Curved line

Curved Line

Curved line

Broken line

Broken Line

Broken line

Parallel lines

Parallel Lines

Parallel lines

Parallel lines

Parallel Lines

Parallel lines

Parallel lines

Parallel Lines

Parallel lines

Right angle at perpendicular lines demonstrated by string on plumb line.

Perpendicular Lines

Right angle at perpendicular lines demonstrated by string on plumb line.

Illustration of point of tangency (line and circle).

Point of Tangency

Illustration of point of tangency (line and circle).

Illustration of radius drawn to point of contact of a tangent.

Point of Tangency

Illustration of radius drawn to point of contact of a tangent.

Illustration of circle with segments labeled and arch.

Segments of Circle and Arch

Illustration of circle with segments labeled and arch.

Illustration of circle with sector and segment used to find area.

Circle With Sector and Segment labeled

Illustration of circle with sector and segment used to find area.

Illustration of partial circle with sector and segment used to find area.

Circle With Sector and Segment labeled

Illustration of partial circle with sector and segment used to find area.

Illustration of circle with diameter and segment used to find area.

Circle With Diameter and Segment labeled

Illustration of circle with diameter and segment used to find area.

A line which is divided into seven equal parts, shown by construction.

Construction of Dividing Lines

A line which is divided into seven equal parts, shown by construction.

A line which is divided into equal parts, shown by construction and square.

Construction of Dividing Lines

A line which is divided into equal parts, shown by construction and square.

Illustration of of construction of an arc when the chord and height of the segment are given.

Construction of Arc When Given the Chord and Height of the Segment

Illustration of of construction of an arc when the chord and height of the segment are given.

An illustration of a zone of a sphere. A zone occurs when a sphere is cut by parallel planes that are equal distances apart. This illustration is the segment of one base.

Zones or Segments of Spheres

An illustration of a zone of a sphere. A zone occurs when a sphere is cut by parallel planes that are…

An illustration of a zone of a sphere. A zone occurs when a sphere is cut by parallel planes that are equal distances apart. This illustration is the segment of two bases.

Zones or Segments of Spheres

An illustration of a zone of a sphere. A zone occurs when a sphere is cut by parallel planes that are…

An 8-inch sphere cut by parallel planes, one 2 inches from center and the other 6 inches from center. This illustration can be used to find the area of the zone and the volume of the segments.

Sphere With 8-inch Diameter Cut by Planes

An 8-inch sphere cut by parallel planes, one 2 inches from center and the other 6 inches from center.…

An illustration of a flanged spherical segment with a diameter of 10 inches. Illustration could be used to find the area.

Flanged Spherical Segment

An illustration of a flanged spherical segment with a diameter of 10 inches. Illustration could be used…

A perpendicular line drawn from point P to straight line RS.

Perpendicular Line Drawn From Point P to Line RS

A perpendicular line drawn from point P to straight line RS.

CD is the projection of AB upon OX. In each case AE=CD and AE=ABcos theta.

Projection of a Line Segment

CD is the projection of AB upon OX. In each case AE=CD and AE=ABcos theta.