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"Semicircular arch, he center of which is in the same line with its springers." — The Encyclopedia Britannica, 1910

Semicircular Arch

"Semicircular arch, he center of which is in the same line with its springers." — The Encyclopedia…

"Flat arch, where the soffit is horizontal and sometimes slightly cambered (dotted line)." — The Encyclopedia Britannica, 1910

Flat Arch

"Flat arch, where the soffit is horizontal and sometimes slightly cambered (dotted line)." — The…

"a, a, a, represents the water-level of a pond or reservoir upon elevated ground. From this pond a line or pipe is laid, passing over a bridge or viaduct at d, and under a river at c. The fountains, at b, b, show the stream rising to its level in the pond, a, at two points of very different elevation." — Wells, 1857

Water Level

"a, a, a, represents the water-level of a pond or reservoir upon elevated ground. From this pond a line…

"An example of a form of reading lamp is seen here. The lamp is mounted on a standard on which it can be raised or lowered at will, and fixed by a thumb screw. The oil reservoir is in two parts, the upper ac being an inverted flask which fits into bb, from which the burner is directly fed through the tube d; h is an overflow cup for any oil that escapes at the burner, and it is pierced with air-holes for admitting the current of air to the center tube of the Argand burner. The lamp is filled with oil by withdrawing the flask ac, filling it, and inverting it into its place. The under reservoir bb fills from it to the burner level ee, on a line with the mouth of ac. so soon as that level falls below the mouth of ac, a bubble of air gets access to the upper reservoir, and oil again fills up bb to the level ec, and so on it goes as long as combustion continues and the supply of oil in ac endures." —The Encyclopedia Britannica, 1910

Reading Lamp

"An example of a form of reading lamp is seen here. The lamp is mounted on a standard on which it can…

"The hides now come to be trimmed and prepared for tanning in the shape in which they are intended ultimately to be sent into the market. An entire untrimmed hide is termed a crop; a side is half a crop, the dividing line of the two sides being shown at EF; a butt is the back portion ABCD, and a bend is half a butt ABFE. G, G are belly pieces, and H, H the cheeks, both together being the offal. When the shoulder (the upper part of the butt) is removed, what remains is the short butt." —The Encyclopedia Britannica, 1910

Hide Divisions

"The hides now come to be trimmed and prepared for tanning in the shape in which they are intended ultimately…

A man wearing a life jacket with a line in his hand.

Sailor

A man wearing a life jacket with a line in his hand.

A form of pen used for drawing lines of even thickness. It commonly consists of two blades which hold ink between them. The distance apart of the points being adjusted by a screw to conform to the desired width of the line.

Ruling Pen

A form of pen used for drawing lines of even thickness. It commonly consists of two blades which hold…

"System of Wheels.—As the wheel and axle is only a modification of the simple lever, so a system of wheels acting on each other, and transmitting the power to the resistance, is only another form of the compound lever. The first wheel a, by means of the teeth, or cogs, around its axle, moved the second wheel, b, with a force equal to that of a lever, the long arm of which extends from the center to the circumference of the wheel, where the power p is suspended, and the short arm from the same center to the ends of the cogs. The dotted line c, passing through the center of the wheel a, shows the position of the lever, as the wheel now stands." —Comstock, 1850

System of Wheels

"System of Wheels.—As the wheel and axle is only a modification of the simple lever, so a system…

"Suppose a number of vessels, of different shapes and sizes to have a communication between them, by means of a small tube, passing from the one to the other. If, now, one of these vessels be filled with water, or if water be poured into the tube A, all the other vessels will be filled at the same instant, up to the line B C. Therefore, the pressure of the water A, balances that in 1, 2, 3, while the pressure in each of these vessels is equal to that in the other, and so an equilibrium is produced throughout the whole series." —Comstock, 1850

Water Pressure

"Suppose a number of vessels, of different shapes and sizes to have a communication between them, by…

"A mountain and spring, showing how the principle of the syphon operates to produce the effect described. Suppose there is a crevice, or hollow in the rock from a to b, and a narrow fissure leading from it, in the form of the syphon, b c. The water from the rill fe, filling the hollow, up to the line a d, it will then discharge itself through the syphon, and continue to run until the water is exhausted down to the l g of the syphon b, when it will cease. Then the water from the rills continuing to run until the hollow is again filled up to the same line, the syphon again begins to act, and again discharges the contents of the reservoir as before, and thus the spring p, at one moment flows with great violence and the next moment ceases entirely." —Comstock, 1850

Intermitting Spring

"A mountain and spring, showing how the principle of the syphon operates to produce the effect described.…

"The refraction of water is beautifully proved by the following simple experiment. Place an empty cup, with a shilling on the bottom, in such a position that the side of the cup will just hide the piece of money from the eye. Then let another person fill the cup with water, keeping the eye in the same position as before. As the water is poured in, the shilling will be come visible, appearing to rise with the water. The effect of the water is to bend the ray of light coming from the shilling, so as to make it meet the eye below the point where it otherwise would. Thus the eye could not see the shilling in the direction of c, since the line, of vision is towards a, and c is hidden by the side of the cup. But the refraction of the water bends the way downwards, producing the same effect as though the object had been raised upwards, and hence it becomes visible." —Comstock, 1850

Cup and Shilling

"The refraction of water is beautifully proved by the following simple experiment. Place an empty cup,…

"The following description of a section of Lord Rosse's telescope, though not so perfect as could be desired, is the best we could obtain. it exhibits a view of the inside of the eastern wall, with the tube, and machinery by which it is moved. A is the mason-work on the ground; B the universal joint, which allows the tube to turn in all directions; C the speculum in the tube; E the eye-piece through which the observer looks; F a pulley by which the tube is moved; H a chain attached to the pulley, and to the side of the tube; I, a chain running to K, the counterpoise; L, a lever connecting the chain M with the tube; Z another chain which passes from the upper part of the tube over a pulley at W, (not seen) and crosses to the opposite wall; X a railroad on which the speculum is drawn either to or from the tube. The dotted line H, shows the course of the weight R, as the tube rises or falls. The tube is moved from wall to wall by a ratchet wheel at R, which is turned by the lever O, on the circle N, the ends of which are fixed in the two walls." —Comstock, 1850

Telescope

"The following description of a section of Lord Rosse's telescope, though not so perfect as could be…

"The twelve signs of the zodiac, together with the Sun, and the Earth revolving around him. When the Earth is at A, the Sun will appear to be just entering the sign Aries, because then, when seen from the Earth, he ranges towards certain stars at the beginning of that constellation. When the Earth is at C, the Sun will appear in the opposite part of the heavens, and therefore in the beginning of Libra. The middle line, dividing the circle of the zodiac into equal parts, is the line of the ecliptic." —Comstock, 1850

Zodiac Signs

"The twelve signs of the zodiac, together with the Sun, and the Earth revolving around him. When the…

A compass placed in some convenient part of a ship on the midship line and provided with vanes, screws, and other apparatus for observing the bearings of heavenly and terrestrial objects.

Azimuth Compass

A compass placed in some convenient part of a ship on the midship line and provided with vanes, screws,…

"The Earth, whose diameter is 7,912 miles, is represented by the globe, or sphere. The straight line passing through its center, and about which it turns, is called its axis, and the two extremities of the axis are the poles of the Earth, A being the north pole, and B the south pole. The line C D, crossing the axis, passes quite round the Earth, and divides it into two equal parts. This is called the equinoctial line, or the equator. That part of the Earth situated north of this line, is caled the northern hemisphere, and that part south of it, the southern hemisphere. The small circles E F and G H, surrounding or including the poles, are called the polar circles." —Comstock, 1850

Earth Divisions

"The Earth, whose diameter is 7,912 miles, is represented by the globe, or sphere. The straight line…

The bone of the middle line of the back.

Backbone

The bone of the middle line of the back.

"Now it is the inclination of the Earth's axis, as above described, which causes the lengths of the days and nights to differ at the same place at different seasons of the year, for on reviewing the positions of the globe at A, it will be observed that the line formed by the enlightened and dark hemispheres, does not coincide with the line of the axis and the pole, but that the line formed by the darkness and the light, extends obliquely across the line of the Earth's axis, so that the north pole is in the light while the south is in the dark. In the position A, therefore, an observer at the north pole would see the sun constantly, while another at the south pole would not see it at all. Hence those living in the north temperate zone, at the season of the year when the earth is at A, or in the Summer, would have long days and short nights, in proportion as they approached the polar circle; while those who live in the south temperate zone, at the same time, and when it would be Winter there, would have long nights and short days in the same proportion." —Comstock, 1850

Earth Axis

"Now it is the inclination of the Earth's axis, as above described, which causes the lengths of the…

"Now it is the inclination of the Earth's axis, as above described, which causes the lengths of the days and nights to differ at the same place at different seasons of the year, for on reviewing the positions of the globe at A, it will be observed that the line formed by the enlightened and dark hemispheres, does not coincide with the line of the axis and the pole, but that the line formed by the darkness and the light, extends obliquely across the line of the Earth's axis, so that the north pole is in the light while the south is in the dark. In the position A, therefore, an observer at the north pole would see the sun constantly, while another at the south pole would not see it at all. Hence those living in the north temperate zone, at the season of the year when the earth is at A, or in the Summer, would have long days and short nights, in proportion as they approached the polar circle; while those who live in the south temperate zone, at the same time, and when it would be Winter there, would have long nights and short days in the same proportion." —Comstock, 1850

Earth Axis

"Now it is the inclination of the Earth's axis, as above described, which causes the lengths of the…

"The skeleton of the trunk and the limb arches seen from the front. 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." —Martin, 1917

Skeletal Trunk

"The skeleton of the trunk and the limb arches seen from the front. C, clavicle; S, scapula; Oc, innominate…

"The spinal cord and nerve-roots. A, a small portion of the cord seen from the ventral side; B, the same seen laterally; C, a cross-section of the cord; D, the two roots of a spinal nerve; 1, ventral fissure; 2, dorsal fissure; 3, surface groove along the line of attachment of the ventral nerve-roots; 4, line of origin of the dorsal roots; 5, ventral root filaments of spinal nerve; 6, dorsal root filaments; 6', ganglion of the dorsal root; 7, 7', the first two divisions of the nerve-trunk after its formation by the union of the two roots. The grooves are much exaggerated." —Martin, 1917

Nerve Roots

"The spinal cord and nerve-roots. A, a small portion of the cord seen from the ventral side; B, the…

Illustration of the proper position for the horizontal line.

Horizontal Line

Illustration of the proper position for the horizontal line.

In this figure <em>BB</em> is the base line; <em>HH</em> the common horizontal or vanishing line; <em>C</em> the centre of view in that vanishing linel <em>LL</em> the vanishing line of the ascent; and <em>C1</em> the centre of view in that vanishing line.

Horizontal Line Diagram

In this figure BB is the base line; HH the common horizontal or vanishing line; C…

This figure represents the whole of the points and lines requisite for working out a drawing in "parallel perspective." 1) The point of sight; 2)The horizontal line; 3) The point of station; 4) The points of measurement.

Parallel Perspective

This figure represents the whole of the points and lines requisite for working out a drawing in "parallel…

This figure comprises the whole of the points and lines preparatory to beginning a drawing in "angular perspective." 1) The point of sight; 2)The horizontal line; 3) The point of station; 4) The nearest corner of the object to be drawn; 5) The ground line of the building or object, lying on that side, and produced from the nearest corner up to the horizontal line, in order to determine the vanishing point marked 5; 6) A line taken from the vanishing point 5, to the point of station 3; 7) A line drawn at right angles to 6, and extending from the point of station to the horizontal line, at its junction with which the vanishing point, marked 8, is determined; 9) A point of measurement obtained by the use of the vanishing point 8; 10) The other point of measurement, obtained by vanishing point 5; 11) The geometrical scale of the building or object upon a base line drawn through the nearest corner.

Angular Perspective

This figure comprises the whole of the points and lines preparatory to beginning a drawing in "angular…

The perspective shown in this plate is parallel perspective; and the subject here intended to be represented is a flat and perfectly square surface, such as the floor of a room, a chess board, or any other such object. 1) The front edge of the given square; 2) One side of it receding to the vanishing point, which also is the point of sight; 3) The other side receding to the same point; 4) A line taken from one corner of the front edge, to the point of measuremen on the opposite side, and giving the perspective width or depth of the square at the intersection of the line 3; 5) A line drawn at the above intersection, and parallel to the front edge; this will give the back of the square. The lines 1, 2, 3, and 5 may then be strongly marked, and the figure will be thus completed. 6) This line is taken from the corner of the front edge to the opposite point of the measurement, showing how exactly either this line, o that marked 4, will give the perspective width of the square. It serves also to find the centre.

Parallel Perspective

The perspective shown in this plate is parallel perspective; and the subject here intended to be represented…

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…

This figure differs from the others because they are solid cubes. Further, the geometrical scale is used for the two cubes, because, being only two, it will be found in this way that fewer lines will be necessary, leaving the figure less intricate and confused. The two frnt sides of the cubes are produced in the same way as far as line 10, which is the farthest corner line of the second cube. 11) The line is drawn from the extremity of 10 to the vanishing point of 7, the two lines being really parallel. 12) Is drawn from the top of 9 to the vanishing point of line 6, these also being parallel. 13) Is drawn from the top of the upright centre line 8, to the vanishing point of 11 and 7, these being all really parallel to each other. 14) Is the far ground line taken from the lower extremity of 9 to the vanishing point of 1, these lines being also parallel. 15 and 16) Are lines drawn from the corner end of 10 and 8 to the vanishing point of 4, the three lines being really parallel. 17 and 18) Are upright lines raised at the intersection of the lines 16 and 15, with the ground line 14, being the far corners of the cubes; they respectively will meet the intersections of lines 11 and 13 with 12. These lines will complete the figure.

Angular Perspective

This figure differs from the others because they are solid cubes. Further, the geometrical scale is…

"A landscape is supposed to be viewed from the spot marked E; and that the spectator is desirous of representing on the plane of his paper a certain portion of the scene as seen by him fom this point. That portion constitutes his real picture. The distance of this picture,- or distance of the eye from the plane of the picture (which is the same thing), -means the distance intervening between the spectator's position, and that point on the ground directly in front of him, where the picture, which he is about to make, ought properly to commence. Upon the choice of a proper and judicious distance the beauty of his work will in a great measure depend. Suppose the landscape to be viewed from the point E, then that portion of the scene which the eye can easily take in, without moving the head, and without the slightest strain upon the optic nerve, will constitute the picture from that point. Now, under this condition the spectator will find that he does not distinctly see the ground immediately before him, but that he obtains a perfectly easy view of it only at some distance from his position at E. It is the space included between the point E (where he is placed), and the supposed point alluded to, and here marked S, that establishes the required distance of the picture, that is, the distance of the eye from the proposed picture. For instance, let S be that point on the ground immediately in front of the eye, and if through S a straight line be supposed to be drawn, perpendicular to the distance ES, this line will pass through and determine the foremost objects of the proposed picture, and therefore at this line the picture must commence."

Distance

"A landscape is supposed to be viewed from the spot marked E; and that the spectator is desirous of…

That an accurate notion of the vertical line may be obtained, the plane of the picture must be supposed to be perpendicular to the horizontal plane. If a straight line be drawn from the spectator's eye, perpendicular to this plane of the picture, that line will fall upon the plane at a point in the horizontal line directly opposite to the eye. This point, C, is called the centre of the picture, or centre of view. In reference to the eye of the spectator, every straight line perpendicular to the plane of the picture appears to converge towards this point or centre. The line which, drawn from the eye of the spectator, determines this centre C, is called the vertical line. It is a straight line through S, perpendicular to the horizontal line, and the base of the picture; and is represented by the line EC.

Vertical Line

That an accurate notion of the vertical line may be obtained, the plane of the picture must be supposed…

A landscape drawing showing the proper position for the horizontal line.

Horizontal Line

A landscape drawing showing the proper position for the horizontal line.

A drawing of a landscape positioning a horizontal line.

Horizontal Line

A drawing of a landscape positioning a horizontal line.

A landscape illustration demonstrating proper positioning of a horizontal line.

Horizontal Line

A landscape illustration demonstrating proper positioning of a horizontal line.

A drawing of a landscape showing the proper position for the horizontal line.

Horizontal Line

A drawing of a landscape showing the proper position for the horizontal line.

Illustration depicting horizontal landscape.

Horizontal Line

Illustration depicting horizontal landscape.

Setting trees to a line

Tree Planting

Setting trees to a line

Diagrammatic section through an arm of the lophophore of Crania. 1, the lip; 2, the base of a tentacle bisected in the middle line; 3, great arm-sinus; 4, small arm-sinus, containing muscle-fibres; 5, tentacular canal; 6, external tentacular muscle; 7, tentacular blood-vessel arising from the cut arm-vesel in the small arm-sinus; 8, chief arm-nerve; 9, secondary arm-nerve; 10, under arm-nerve.

Brachiopoda

Diagrammatic section through an arm of the lophophore of Crania. 1, the lip; 2, the base of a tentacle…

Stamens of the mint family. Of a Monarda: the two anther-cells with bases divergent so that they are transverse to the filament, and their contiguous tips confluent, so as to form one cell opening by a continuous line. Fig 301; Of a Calamintha: the broad connective separating the two cells. Fig 302; Of a Sage (Salvia Texana; with long and slender connective resembling forks of the filament, one bearing a good anther-cell wholly wanting. Fig 304; Of a White Sage, Audibertia grandiflora; the lower fork of connective a mere vestige. Fig. 305; Of another White Sage (A. stachyoides), the lower fork of connective suppressed.

Stamens

Stamens of the mint family. Of a Monarda: the two anther-cells with bases divergent so that they are…

The shape of the earth is that of a round ball or sphere slightly flattened at two opposite sides. Such a body is termed a <em>spheroid</em>. There are two kinds of spheroids-<em>oblate</em> and <em>prolate</em>; the former as the shape of an orange, the latter that of a lemon. The straight line that runs through the centre of a sphere or spheroid and terminates at the circumference is called the <em>diameter</em>. If the sphere rotates-that is, moves around like a top-the diameter on which it turns is called the <em>axis</em>. In the oblate spheroid the axis is the shorter diameter; in the prolate spheroid the axis is the longer diameter.

Oblate and Prolate Spheroid

The shape of the earth is that of a round ball or sphere slightly flattened at two opposite sides. Such…

This is a line engraving by Sir Anthony Van Dyck. Pictures is Elizabeth, the wife of William Cavendish. The original engraving was done by Pierre Lombard.

Elizabeth, Countess of Devonshire

This is a line engraving by Sir Anthony Van Dyck. Pictures is Elizabeth, the wife of William Cavendish.…

This is a line engraving by Sir Anthony Van Dyck. The picture is one of many done for Charles I. The original picture can be found in the Louvre

Charles I Attended by the Marquis of Hamilton

This is a line engraving by Sir Anthony Van Dyck. The picture is one of many done for Charles I. The…

Section through the Head and Neck on the Median Line. 1. Medulla Oblongata 2. Pons 3. Right lobe of cerebrum 4. Cerebellum in section 5. Blood vessel 6. Corpus Striatum 7. Nasal Passage 8. Nasal bone 9. Soft Palate 10. Hard Palate 11. Tongue 12. Epiglottis 13. Os Hyoides 14. Oesaphagus 15. Spinal 16. Larynx 17. Windpipe

Sectional view of the Head

Section through the Head and Neck on the Median Line. 1. Medulla Oblongata 2. Pons 3. Right lobe of…

During new and full moon, the earth, moon, and sun are all in the same straight line, but, that during the first and last quarters, they are at right angles. The portions of the earth and moon turned toward the sun are illumined, the shaded portions are in the darkness. To an observer on the earth, the moon, at <em>a</em>, appears new, since the dark part is turned toward the person; at <em>b</em>, however, it must appear full, since the illumined portions are toward the person. At <em>c</em>, and <em>d</em>, the positions of the quarters, only one-half of the illumined half, or one quarter, is seen.

Cause of the Phases of the Moon

During new and full moon, the earth, moon, and sun are all in the same straight line, but, that during…

A sailor being tossed a life line after ship wrecked.

Shipwrecked Sailor

A sailor being tossed a life line after ship wrecked.

Diagram of a shoot with its leaves 5-ranked, with a spiral line drawn from the attachment of one leaf to the next, and so only the parts on the side turned from the eye are fainter.

Five-ranked

Diagram of a shoot with its leaves 5-ranked, with a spiral line drawn from the attachment of one leaf…

A ground-plan of the 5-ranked shoot; the section of the leaves; a dotted line drawn from the edge of one leaf to that of the next marks out the spiral.

Five-ranked

A ground-plan of the 5-ranked shoot; the section of the leaves; a dotted line drawn from the edge of…

Diagram of the calyx and corolla, the place for the missing petal marked by a dotted line.

Larkspur

Diagram of the calyx and corolla, the place for the missing petal marked by a dotted line.

Wing of an owlet-moth, with all the markings defined and named.-Right wings: b, basal line; t.a., transverse anterior line; m, median line or shade; t.p., transverse posterior line; st., sub-terminal line; t., terminal line; sm., sub-median vein; apex of hind wing; o.m., outer margin; i.m., inner margin. Left wings: b.d., basal dash; cl., claviform; or., orbicular spot; ren., reniform spot; ap., apical spot; c.m., costal margin; o.m., outer margin; i.m. inner margin; h.a., hind angle; d.s., discal spot; e.l., exterior line; an., anal angle.

Owlet Moth

Wing of an owlet-moth, with all the markings defined and named.-Right wings: b, basal line; t.a., transverse…

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…

A line moves in a plane and it therefore envelopes a plane curve.

Plane Curve

A line moves in a plane and it therefore envelopes a plane curve.

Five points are given, of which not three are in a line, a curve of second order may be drawn through all of them.

Second Order Curve

Five points are given, of which not three are in a line, a curve of second order may be drawn through…

The three points in which any line cuts the sides of a triangle and the projections, from any point in the plane, of the vertices of the triangle on to the same line are six points in involution.

Involution

The three points in which any line cuts the sides of a triangle and the projections, from any point…

The lines which join corresponding points in an involution on a conic all pass through a fixed point; and reciprocally, the points of intersection of conjugate lines in an involution among tangents to a conic lie on a line.

Conic Involution

The lines which join corresponding points in an involution on a conic all pass through a fixed point;…

Two planes lie perpendicular to one another. A line perpendicular to plane 1 and a line perpendicular to plane 2 will meet at a point, A, and form a perpendicular intersection.

Perpendicular Planes

Two planes lie perpendicular to one another. A line perpendicular to plane 1 and a line perpendicular…

To find the projections of a line which joins two points, A, B given by their projections.

Line Projection

To find the projections of a line which joins two points, A, B given by their projections.

The straight line is the simplest type of locus and the simplest first degree equation.

Straight Line

The straight line is the simplest type of locus and the simplest first degree equation.

Illustration 1 of the Dedekind axiom.

Dedekind Property 1

Illustration 1 of the Dedekind axiom.

Illustration 2 of the Dedekind axiom.

Dedekind Property 2

Illustration 2 of the Dedekind axiom.