ClipArt ETC
"The compressed air manometer consists of a strong graduated glass tube of uniform narrow bore, closed at the top and fixed hermetically into the neck of a wide iron cylinder. The tube contains dry air, and its lower end dips below the surface of mercury contained in the cylinder. Attached to the side of the cylinder is a tube A, with a stop-cock, to afford communication with the vessel the pressure in which is to be measured. When the manometer is attached to the vessel containing compressed gas the mercury rises in the glass tube till the pressure of the air confined in the tube plus the height of the mercury column above the level of the mercury in the cylinder is equal to the pressure on the surface of mercury in the cylinder." —The Encyclopedia Britannica, 1903

Compressed Air Manometer

"The compressed air manometer consists of a strong graduated glass tube of uniform narrow bore, closed…

"In this the four lateral planes are rectangular and equal; they may be either oblong or square; in the latter case the form is the cube." —The Encyclopedia Britannica, 1903

Primitive Crystal

"In this the four lateral planes are rectangular and equal; they may be either oblong or square; in…

"When the base is a rhomboid, and the prism stands erect, it is only the opposite laeral faces that can be equal. The form is called a right rhomboidal prism." —The Encyclopedia Britannica, 1903

Primitive Crystal

"When the base is a rhomboid, and the prism stands erect, it is only the opposite laeral faces that…

The perspective in this plate is "angular perspective," and the figure it represents is a flat square surface; its dimensions are supposed to be either twenty feet or twenty inches. 1) Two lines drawn from the nearest corner of theboard, to the horizontal line, and at a distance from each other equal to the thickness of the board; this fixes the vanishing point at 1. 2) A line drawn from the above vanishing point to the point of station. 3) A line taken at right angles to 2, from the point of station, and fixing on the horizontal line the position of the vanishing point 3. 4) Two lines drawn from the nearest corner of the board to the vanishing point 3, similarly to the previously drawn lines 1. 5) One point of measurement, obtained in the usual way, by the distance of 3 from the point of station. 6) The point of measurement. 7) The line of the geometrical scale, being a line drawn across the base of the nearest corner, and marked according to scale, twenty feet or twenty inches. 8,8) Lines taken from either end of the geometrical scale towards the point of measurement, but extending no farther than where they meet the lines 1,1, and 4,4. 9,10) Small perpendicular lines drawn at the above intersections, by which the width of the board is ascertained. 11) The side of the board opposite and really parallel to that marked 4, and therefore tending to the same vanishing point. 12) The back of the board, opposite and parallel to the front marked 1, and consequently tending to the same vanishing point. The lines 1,1; 4,4; 11 and 12, being strongly marked, the figure will be completed.

Angular Perspective

The perspective in this plate is "angular perspective," and the figure it represents is a flat square…

Two upright oblong figures are here represented in parallel perspective. They may be imagined to resemble the sides and fronts of houses, or their blank walls. One of the figures has two others attached to it of equal dimensions; and these additions might be similarly multiplied to any extent, by the numbers, 7, 8, 9 and 10, in the followig rules. 1) Lines forming to complete fronts of two separate and detached oblongs. 2) The geometrical scale at the base, marked twenty feet. 3) The ground lines of the fronts running to the vanishing point. 4) The top lines tending to vanishing point. 5) Lines from the geometrical scale, to the points of measurement, determining the perspective depths of the oblongs. 6) Perpendicular lines raised at the intersection of the lines 3 and 5, and giving the farthest upright corner lines of the oblongs. The two figures will thus be completed. The remaining lines inserted in the figure are intended to give two other oblongs (or rather their retiring sides) attached to the first, and supposed to be of the same dimensions. They are determined first by finding the centre 7 of the near corner line 1. From 7 a line is drawn to the vanishing point. A line marked 8 is then drawn from the near extremity of 1 through 6, where it is cut by 7; at its intersection with the bottom line 3, the perpendicular line 9 is raised, and another oblong front is completed. A line 10 is drawn, and determined as the line 8 was, from the top of 6, and by crossing the lines 7 and 3. The lines 13, 14, and 15, are inserted merely to show the inner side and back of the other oblong, as they would be seen were the object made of glass. Thus 13,13 are lines for the top and bottom of the back; formed by drawing them to the vanishing point; 14,14 are the top and bottom lines of the farthest side, found by straight lines being drawn from both ends of , until they meet 13,13; at which point of meeting the upright corner of the oblong are completed.

Parallel Perspective

Two upright oblong figures are here represented in parallel perspective. They may be imagined to resemble…

This object is a cube, having therefore all its faces of equal dimensions; and as both sides recede, "angular perspective" is employed. The point of sight, horizontal line, and point of station, having been fixed upon, the line A is first to be drawn, touching the bottom of the nearest corner, and is for the geometrical scale or height of the cube, which, in this instance, will be called twelve feet; that is, twelve feet must be marked on the scale from the corner on either side. 1) The ground line of the square, taken from the centre of the geometrical scale line to the horizontal line; by its junction with which is determined the vanishing point or that side. 2) A line drawn from the above vanishing point to the point of station. 3) A line drawn at right angles at the point of station to the line 2, as far as the horizontal line, its intersection with which will give the correct vanishing point to the other side. 4) The ground line of the cube running to the last vanishing point. 5) The nearest corner of the cube, twelve feet in height, being equal to the width. The points of measurement are next to be ascertained, and to be marked in the usual way; and the lines B drawn from the ends of the geometrical scale towards the point of measurement give the perspective width or depth of both sides. This is found at their cutting of the ground lines 1 and 4. The line 6 represents the top line of one side of the cube, and runs from the nearest corner to the vanishing point. 7) The other top line; and it is drawn to the other vanishing point. 8) The far corner line raised vertically from the crossing of the lines B and 1. 9) The other corner line raised vertically from the intersection of the lines B and 4. The lines 1, 4, 5, 6, 7, 8, 9, being strengthened, the figure is complete.

Angular Perspective

This object is a cube, having therefore all its faces of equal dimensions; and as both sides recede,…

This cube has four additional cubes of equal dimensions. This is effected by first drawing the cube in the order and then finding the centre of the upright line 5, that being the nearest corner line of this first cube. The centre being found at 10, take the line 10 to the vanishing point for that side of the cube; this will give the centres of all the other upright lines of that side of all the added cubes. The line 11 is drawn from the top of the corner line 5, through the intersection of 8 and 10, until it meets the ground line 1, at its junction with which the upright line is raised for the far corner line 12 of the second cube. The three other cubes are described precisely in the same manner, being found by the diagonal lines traversing each pair of the cubes, through the intersection of the centre line 10, with each perpendicular line raised from the meeting of the previous diagonal line with the ground line 1. It will be perceived that a further distance of twelve feet is added to one side of the geometrical scale, and marked A. This is done merely to prove the correctness of the first diagonal line 11, passing through the centre line 10, to determine the perspective depth of the second cube. For if a line be taken from the end of the geometrical scale A to the point of measurement on the horizontal line, it will be found to meet the ground line 1 at exactly the same point; thus proving the truth of both modes of drawing. The former mode, however, is more convenient where a number of cubes are to be drawn; as the geometrical scale might extend far beyond the limits of the paper, and consequently give much more trouble.

Angular Perspective

This cube has four additional cubes of equal dimensions. This is effected by first drawing the cube…

Thread like antenna when the joints are nearly even throughout, cylindrical, tolerably equal in length, and similar in general appearance.

Filiform antenna

Thread like antenna when the joints are nearly even throughout, cylindrical, tolerably equal in length,…

Diagram of the topography of the main groups of foci in the motor field of chimpanzee

Brain

Diagram of the topography of the main groups of foci in the motor field of chimpanzee

A Great Circle is one which would be formed on the earth's surface by a plane passing through the earth's centre, hence dividing it into two equal parts. All great circles, therefore, divide the earth into two hemispheres.

Great Circle

A Great Circle is one which would be formed on the earth's surface by a plane passing through the earth's…

A small circle is one formed by a plane which does not cut the earth into two equal parts. The small circles are the <em>parallels</em>.

Small Circle

A small circle is one formed by a plane which does not cut the earth into two equal parts. The small…

The Meridian of any given place is that half of the meridian circle which passes through that place and both poles. A meridian of any place reaches from that place to both poles, and therefore is equal to one-half of a great circle, and, with the meridian directly opposite to it, forms a great circle called a meridian circle. There are as many meridians as there are places on the equator or on any parallel. Parallels are small circles which pass around the earth parallel to the equator.

Meridians and Parallels

The Meridian of any given place is that half of the meridian circle which passes through that place…

These animalcule are so small that 1,000,000 are equal in bulk to only one cubic inch. They appear to live in the layers of water near the surface, and after death to fall gradually to the bottom of the sea.

Foraminifera

These animalcule are so small that 1,000,000 are equal in bulk to only one cubic inch. They appear to…

Bread-Fruit is the pulpy fruit of a tree which grows only in the tropics. The tree yields fruit during most of the year, and is said to be a native of the South Sea Islands, though it is now quite common in the Friendly and Society groups, and in many of the neighboring islands.

Bread Fruit

Bread-Fruit is the pulpy fruit of a tree which grows only in the tropics. The tree yields fruit during…

Fur Seals make up one of the two distinct groups of mammals called "seals". Both the fur seals and the true seals are members of the Pinnipedia, which is usually regarded as a suborder of the order Carnivora but sometimes as an independent order. However, the fur seals, like their close relatives the sea lions, retain some ability to walk on land as their hind limbs can be brought forward under the body to bear the animal's weight, and retain small but visible external ears.

Seals and Walrus

Fur Seals make up one of the two distinct groups of mammals called "seals". Both the fur seals and the…

Phylloxera Vastatrix- a, an unaffected rootlet of grape; b, rootlets with newly-formed galls; c, same, with old and dried-up tissue; dd, groups of the lice on roots and rootlets.

Phylloxera Vastatr

Phylloxera Vastatrix- a, an unaffected rootlet of grape; b, rootlets with newly-formed galls; c, same,…

The cross-ratio of four points in a line is equal to the cross-ratio of their projections on any other line which lies in the same plane with it.

Cross-Ratio Four Points

The cross-ratio of four points in a line is equal to the cross-ratio of their projections on any other…

All triangles formed by a tangent and the asymptotes of an hyperbola are equal in area.

Hyperbola Tangent Triangles

All triangles formed by a tangent and the asymptotes of an hyperbola are equal in area.

The segments between the point of intersection of two tangents to a conic and their points of contact are seen from a focus under equal angles. the ratio of the distances of any point on a conic from a focus and the corresponding directrix is constant.

Parabola Foci Properties

The segments between the point of intersection of two tangents to a conic and their points of contact…

Generating a hyperbola from two equal and parallel circular disks.

Generate Hyperbola

Generating a hyperbola from two equal and parallel circular disks.

A square divided into equal squares, like a chessboard, in each of which is placed one of a series of consecutive numbers from 1 up to the square of the number of cells in a side, in such a manner that the sum of the numbers in each row or column and in each diagonal is constant.

Magic Square

A square divided into equal squares, like a chessboard, in each of which is placed one of a series of…

The lines of contact are equal, but the axes are neither parallel to each other, or the line of contact.

Lateral Sliding Contact

The lines of contact are equal, but the axes are neither parallel to each other, or the line of contact.

Method to bisect an angle

Bisect An Angle

Method to bisect an angle

Method to construct an isosceles triangle

Construct Isosceles Triangle

Method to construct an isosceles triangle

Six equal circles tangent to each other and to the sides of the triangle

Circle Triangle Tangents

Six equal circles tangent to each other and to the sides of the triangle

Equal circles inside and tangent to the outside circle, also tangent to each other

Circle to Circle Tangents

Equal circles inside and tangent to the outside circle, also tangent to each other

"Hydrochloric acid...is placed in the tubes a. The threeway stopcocks b are turned so that there is a passage from c to d and a saturated solution of sodium chloride is drawn from the dishes i into the collecting tubes e until they are filled. The stopcocks are then tunred so that there is a passage from f to d. The current is turned on, and as soon as the hydrochloric acid above the anode is saturated with chlorine, the stopcocks are turned so that the hydrogen and chlorine will pass into the collecting tubes e. When the upper surfaces of the sodium chloride solution are just above the support g, it is inclined, if need be, so as to mark the relative height of the solution in the collecting tubes. the lower support h is then made parallel with g. The solution between g and h is displaced in the same time, showing that equal volumes of hydrogen and chlorine are obtained by the electrolysis of hydrochloric acid." -Brownlee 1907

Electrolysis of Hydrochloric Acid

"Hydrochloric acid...is placed in the tubes a. The threeway stopcocks b are turned so that there is…

"Suppose our volume of hydrogen to unite with the volume of chlorine; if one particle of hydrogen combines with one particle of chlorine, it is evident that we should have four pairs; that is four particles of hydrogen chloride. These four particles of hydrogen chloride would occupy the same volume as four particles of hydrogen, or of chlorine, since dqual numbers of particles of gases occupy equal spaces. We should then expect one volume of hydrogen chloride to be formed." -Brownlee 1907

Combinational Volume

"Suppose our volume of hydrogen to unite with the volume of chlorine; if one particle of hydrogen combines…

Represents the combination of a cube and an octahedron, with both faces being equal.

Cubo-octahedron

Represents the combination of a cube and an octahedron, with both faces being equal.

"This is a double wedge-shaped solid bounded by four equal isosceles triangles." -The Encyclopedia Britannica 1910

Tetragonal Bishenoids

"This is a double wedge-shaped solid bounded by four equal isosceles triangles." -The Encyclopedia Britannica…

"...consisting of six rhomb-shaped faces with the edges all of the equal lengths: the faces are perpendicular to the planes of symmetry." -The Encyclopedia Britannica 1910

Direct Rhombohedra

"...consisting of six rhomb-shaped faces with the edges all of the equal lengths: the faces are perpendicular…

"...consisting of six rhomb-shaped faces with the edges all of the equal lengths: the faces are perpendicular to the planes of symmetry." -The Encyclopedia Britannica 1910

Indirect Rhombohedra

"...consisting of six rhomb-shaped faces with the edges all of the equal lengths: the faces are perpendicular…

"Lines of force of a charged sphere and a conductor under induction. The negative electrification on the end a of the cylinder indicates that an equal number of lines set out from that end." -Hawkins, 1917

Lines of Force under Induction

"Lines of force of a charged sphere and a conductor under induction. The negative electrification on…

"Diagram of a multiple or parallel connection. When connected in this manner the voltage of the battery is the same as that of a single cell, but the current is equal to the amperage of a single cell multiplied by the number of cells." -Hawkins, 1917

Parallel Connection

"Diagram of a multiple or parallel connection. When connected in this manner the voltage of the battery…

"This will be understood, when we consider that the reaction of b is just equal to the action of a, and that each of the other balls, in lke manner, ac, and react, o n the other, until the motion of a arrives at f, which, having no impediment, or nothing to act upon, is itself ut in motion." -Comstock 1850

Action and Reaction

"This will be understood, when we consider that the reaction of b is just equal to the action of a,…

"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,…

"Suppose the weight, B to be sixteen pounds and suppose the fulrum to be placed so near it, as to be raised by the power A, of four pounds hanging equally distant from the fulcrum and the end of the lever. If now the power A be removed, and another of two pounds, C, be placed at te end of the lever, its force will be just equal to A, placed at the middle of the lever." -Comstock 1850

Simple Lever System

"Suppose the weight, B to be sixteen pounds and suppose the fulrum to be placed so near it, as to be…

"In order that the successive wheels should revolve in the same time, and their circumfrences should be just equal to the length of rope passing between them...By this construction, although the length of rope passing over each was different, yet their revolutions are equal, both with respect to time and number." -Comstock 1850

White's Pulley

"In order that the successive wheels should revolve in the same time, and their circumfrences should…

"Therefore, the small quantity in the spout balances the large quantity in the pot, or presses with the same force downwards, as that in the body of the pot presses upwards." -Comstock 1850

Water Pressure

"Therefore, the small quantity in the spout balances the large quantity in the pot, or presses with…

"The fire engine is a modification of the forcing pump. It consists of two such pumps, the pistons of which are moved by a lever whith equal arms, the common fulcrum being at C." -Comstock 1850

Fire Engine

"The fire engine is a modification of the forcing pump. It consists of two such pumps, the pistons of…

"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…

"Suppose the mirror, a b, to be placed on the side of a room, and a lamp to be set in antoher room, but so situated as that its light would shine upon the glass. The lamp itself could not be seen by the eye placed at e, because the partition d is between them; but its image would be visible at e, beacuse the angle of the incident ray, coming from the light, and that of the reflected ray which reaches the eye, are equal." -Comstock 1850

Plane Mirror

"Suppose the mirror, a b, to be placed on the side of a room, and a lamp to be set in antoher room,…

"The incident rays, a and b, being parallel before they reach the reflectors, are thrown off at unequal angles in respect to each other, for b fallson the mirror more obliquely than a, and consequently is thrown off more obliquely in a contraty direction, therefore, then angles of reflection being equal to those of incidence, the two rays meet at c." -Comstock 1850

Plane Inclined Mirrors

"The incident rays, a and b, being parallel before they reach the reflectors, are thrown off at unequal…

The base of the skull. "The lower jaw has been removed. At the lower part of the figure is the hard palate forming the roof of the mouth and surrounded by the upper set of teeth. Above this are the paired opening of the posterior nares, and a short way above the middle of the figure is the large median foramen magnum, with the bony convexities (or occipital condyles) which articular with the atlas, on its sides. It will be seen that the part of the skull behind the occipital condyles is about equal in size to that in front of them; in an ape the portion in front of the occipital condyles would be much larger than that behind them." &mdash;Newell, 1900

Base of the Skull

The base of the skull. "The lower jaw has been removed. At the lower part of the figure is the hard…

"When a feather and a cent are dropped from the same height, the cent reaches jthe ground first. this is not because the cent is heavier, bu because the feather meets with more resistance from the air in proportion to its mass. If this resistance can be removed or equalized, the two bodies will fall equal distances in equal times, or with the same velocity. The resistance may be avoided by dropping them in a glass tube from which the air has been removed. The resistances may be nearly equalized by making the two falling bodies of the same size and shape bu of different weights, as in the preceding experiment." -Avery 1895

Velocities of Falling Bodies

"When a feather and a cent are dropped from the same height, the cent reaches jthe ground first. this…

"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…

"...the mechanical advantage of this machine (wheel and axle) equal the ratio between the radii, diameters, or circumferences of the wheel and of the axle." -Avery 1895

Wheel and Axle with Rope and Bucket

"...the mechanical advantage of this machine (wheel and axle) equal the ratio between the radii, diameters,…

"Pressure exerted anywhere upon a liquid inclosed in a vessel is transmitted undiminished in all direction, and acts with the same force upon all equal surfaces, and in a direction at right angles to those surfaces." -Avery 1895

Pascal's Law

"Pressure exerted anywhere upon a liquid inclosed in a vessel is transmitted undiminished in all direction,…

"Get a lamp-chimney, preferably cylindrical. With a diamond or a steel glass-cutter, cut a disk of window glass a little larger than the cross-section of the lamp-chimney. Pour some fine emery powder on the disk, and rub one end of the chimney upon it, thus grinding them until they fit accurately...place [the chimney] under the water as shown. the upward pressure of the water will hold the disk in place. Pour water carefully into the tube; the disk will fall as soon as the weight of the water in the chimney plus the weight of th disk, exceeds the upward pressure of the water." -Avery 1895

Water Pressure Experiment

"Get a lamp-chimney, preferably cylindrical. With a diamond or a steel glass-cutter, cut a disk of window…

"It is evident that, when a solid is immersed in a fluid, it will displace exactly its own volume of the fluid. Immerse a solid cube one centimeter on each edge in water, so that its upper face shall be level and one centimeter below the surface of the liquid, as shown. The lateral pressures upon any two opposite vertical surfaces of the cube, as a and b, are clearly equal and opposite." -Avery 1895

Archimedies Principle

"It is evident that, when a solid is immersed in a fluid, it will displace exactly its own volume of…

"...represents two sets of sound waves with like periods and phases but different amplitudes." -Avery 1895

Waves with Different Amplitudes with Equal Periods

"...represents two sets of sound waves with like periods and phases but different amplitudes." -Avery…

"...represents two wave systems of equal periods and amplitudes but of opposite phases." -Avery 1895

Waves with Equal Periods and Opposite Amplitudes

"...represents two wave systems of equal periods and amplitudes but of opposite phases." -Avery 1895

"The apparatus shown is used to prove that incident rays and reflected rays are equal." -Avery 1895

Reflected Light

"The apparatus shown is used to prove that incident rays and reflected rays are equal." -Avery 1895

"When radiant energy passes through a medium bounded by parallel planes, the refractions at the two surfaces are equal and contrary in direction. The direction after passing through the plate is parallel to the direction before entereing the plate; the rays merely suffer lateral aberration." -Avery 1895

Refraction by Plates

"When radiant energy passes through a medium bounded by parallel planes, the refractions at the two…

"Coil some No. 12 copper wire throuh holes in a board, as shown, and pass a strong current through it. Sprinkle iron filling as before and note the effect. Such a coil of conducting wire, wound so as to afford a number of equal and parallel circular electric circuits arranged upon a common axis, is called a solenoid." -Avery 1895

Solenoid

"Coil some No. 12 copper wire throuh holes in a board, as shown, and pass a strong current through it.…

"A cube is a prism whose faces are ends are squares. All the faces of a cube are equal." &mdash;Hallock 1905

Cube

"A cube is a prism whose faces are ends are squares. All the faces of a cube are equal." —Hallock…

"From on pan suspend a hollow cylinder of metal t, and below that a solid cylinder a of the same size as the hollow part of the upper cylinder. Put two weights in the other scale pan until they sxactly balance the two cylinders. If a be immersed in water, te scale pan containing the weights will descend, showing that a has lost some of its weight. Now fill t with water, and the volume of water that can be poured into t will equal that displaced by a. The scale pan that contains the weights will gradually rise until t is filled, when the scales will balance again." —Hallock 1905

Archimedes Principle

"From on pan suspend a hollow cylinder of metal t, and below that a solid cylinder a of the same size…

"The maximum safe load in pounds that should be allowed at the end of any cylindrical cantilever is equal to the cube of its diameter in inches multiplied by .6 of the constant given in the tale, and the product divided by its length in feet." &mdash;Hallock 1905

Cylindrical Cantilever

"The maximum safe load in pounds that should be allowed at the end of any cylindrical cantilever is…