The irregularity of spacing has thus the effect of a convex lens, which accelerates the marginal relatively to the central rays.
Convex spectacles were invented towards the end of the 13th century.
in diameter, sessile, and generally in pairs, and are made up of large angular scales, slightly convex exteriorly, and with a sharp point in the centre.
Most of the permeability-temperature curves were more or less convex towards the axis of temperature, and in all the experiments except those with annealed iron and steel wire, the permeability was greatest at the lowest temperature.
When kept in non-metallic vessels they take the shape of a convex meniscus.
In the disk plough, which is built both as a riding and a walking plough, the essential feature is the substitution of a concavo convex disk, pivoted on the plough beam, for the mould-board and share of the ordinary plough.
The convex side rests upon the duchy of Coburg and is in part bounded by Bavaria, while the concave side, turned towards the north, contains portions of four other Thuringian states and Prussia between its horns, which are 46 m.
32), are a large family of beetles, well known by their rounded convex bodies, usually shining and hairless.
1, A), are usually convex above, with straight hind margins (dorsa); when the elytra are closed, the two hind margins come together along the mid-dorsal line of the body, forming a suture.
It may be applied to the end of a tube much shorter than its focal distance, by having another convex glass within the tube, to shorten the focal distance of that which is cut in two.
A third type of musk-ox skull is, however, known from North America, namely one from the celebrated Big-Bone Lick, Kentucky, on which the genus and species Bootherium bombifrons was established, which differs from all the others by its small size, convex forehead and rounded horn-cores, the latter being very widely separated, and arising from the sides of the skull.
Most of the Chrysomelidae are metallic in colour and convex in form; in some the head is concealed beneath the prothorax, and the so-called "tortoise" beetles (Cassidinae) have the elytra raised into a prominent median ridge.
At one end of it paper was stretched, and at the other a convex lens was fitted in a hole, the image being viewed through an aperture at the top of the box.
It has, however, been shown that, if the magnetizing force is carried far enough, the curve always becomes convex to the axis instead of meeting it.
The prothorax is convex in front, and is usually drawn out behind into a prominent process on either side, while the elytra are elongate and tapering.
This was done in 1612 by Christoph Scheiner, who fully described his method of solar observation in the Rosa Ursina (1630), demonstrating very clearly and practically the advantages and disadvantages of using the camera, without a lens, with a single convex lens, and with a telescopic combination of convex object-glass and concave enlarging lens, the last arrangement being mounted with an adjustable screen or tablet on an equatorial stand.
The white perianth is six-parted, the outer three segments being larger and more convex than the inner series.
8) or saddle-shaped; the anterior surface is concave in a transverse, but convex in a vertical direction, which on posterior surface shows the conditions reversed.
The communication with the atrium is guarded by a valvula cardiaca dextra, which only in function represents the mammalian tricuspid; it consists of an oblique reduplication of the muscular fibres together with the endocardiac lining of the right ventricle, while the opposite wall is convex and forms neither a velum nor papillary muscles, nor chordae tendineae.
deep. They run in strings irregularly from east to west, corresponding in this with their individual direction, the convex face of the falk being towards the west, i.e.
The delicately carved convex roof, composed of a single block, was surmounted by the tripod.
A map of Italy in the baptistery of St Peter at Rome has occasionally been described as a relief, though it is merely a rude outline map of Italy, by Carlo Fontana (1698), carved into a convex surface.
The typical Egyptian obelisk is an upright monolith of nearly square section, generally to diameters in height, the sides slightly convex, tapering upwards very gradually and evenly, and terminated by a pyramidion whose faces are inclined at an angle of 60°.
The convex slopes falling from the Prussian position towards Metz gave plenty of cover to the French, and the setting sun shone full in the faces of the Prussian artillerymen.
If the trapezette, as seen from above, is everywhere convex or everywhere concave, the true area lies between C 1 and T1.
The arches bear on the convex outer side the delicate arborescent gills, and on the concave inner side develop a membranous septum with vermicular perforations, a special sifting or filtering contrivance through which the water absorbed by the mouth has to pass before reaching the respiratory organs of the branchial apparatus.
The sand usually forms isolated hillocks, called medanos, of a half-moon shape, having their convex sides towards the tradewind.
He also had some knowledge of the properties of concave and convex lenses and mirrors in forming images.
In an Italian translation of Euclid's Optica, with commentary, Egnacio Danti (1573), after discussing the effects of plane, convex and concave reflectors, fully describes the method of showing reversed images passing through an aperture in a darkened room, and shows how, by placing a mirror behind the aperture, unreversed images might be obtained, both effects being illustrated by diagrams. F.
Some excellent instruments of the second type were subsequently made by Dollond's eldest son Peter, in which for the " convex glass within the tube " was substituted an achromatic object-glass, and outside that a divided negative achromatic combination of long focus.
CAMERA OBSCURA, an optical apparatus consisting of a darkened chamber (for which its name is the Latin rendering) at the top of which is placed a box or lantern containing a convex lens and sloping mirror, or a prism combining the lens and mirror.
The eyepiece ab consists of two plano-convex lenses a, b, of nearly the same focal length, and with the two convex sides facing each other.
The mouth of the pitcher has a corrugated rim (peristome) formed by incurving of the margin, the convex surface of which is firm and shining.
vulgaris) is brown in colour, and produces a bun-shaped egg, spiky on the convex surface, and attached to a water-weed or some object by its flattened side.
20), for example - are specialized for an aquatic life, the body being convex and smooth as in the Dyticidae, and the intermediate and hind-legs fringed for swimming.
On either side a variable amount of convex area is occupied by the compound eye; in many insects of acute sense and accurate flight these eyes are very large and sub-globular, almost meeting on the middle line of the head.
Erben is the author of a rough relief on a convex surface (1842), but the finest example of this description is a relief of Italy, by Cesar Pomba and H.
The great bulk of the silver work is in the form of bowls of different sizes, in shape something like the lower half of a barrel, only more convex, of betel boxes, cups and small boxes for lime.
The second edition, in which he in the same words discloses the use of a convex lens in the aperture as a secret he had intended to keep, was not published till 1589, thirty-one years after the first.
The lens used by Barbaro was an ordinary convex or old man's spectacle-glass; concave, he says, will not do.
He also demonstrates how enlarged images can be produced and projected on paper by using a concave lens at a suitable distance behind the convex, as in modern telephotographic lenses.
Trans., 1668, 3, p. 741) a camera lucida on the principle of the magic lantern, in which the images of illuminated and inverted objects were projected on any desired scale by means of a broad convex lens through an aperture into a room where they were viewed by the spectators.
One was a wooden box with a projecting tube in which a combination of a concave with a convex lens was fitted, for throwing an enlarged image upon the focusing screen, which in its proportions and application is very similar to our modern telephotographic objectives.
Sir Isaac Newton, in his Opticks (1704), explains the principle of the camera obscura with single convex lens and its analogy with vision in illustration of his seventh axiom, which aptly embodies the correct solution of Aristotle's old problem.
The vapour pressure composition curve will be convex to the axis of compositions, the maximum vapour pressures corresponding to pure A and pure B, and the minimum to some mixture of A and B.
Such cases should be treated with convex lenses, which should be theoretically of such a strength as to fully correct the hypermetropia.
becomes impossible, convex lenses should be used for reading of such a strength as to enable the eye to see clearly about 8 in.
Rhinophis sanguineus lives in southern India; it is black above with a bluish gloss, the belly is bright red with black spots, like the convex tail-shield.
focal length, composed of a double concave flint lens and a double convex crown.
More or less nearly related to the saiga is the chiru, Pantholops hodgsoni, of Tibet, characterized by the long upright black horns of the bucks, and the less convex nose, in which the nostrils open anteriorly instead of downwards.
In the Diversarum Speculationum Mathematicarum et Physicarum (1585), by the Venetian Giovanni Battista Benedetti, there is a letter in which he discusses the simple camera obscura and mentions the improvement some one had made in it by the use of a double convex lens in the aperture; he also says that the images could be made erect by reflection from any plane mirror.
The use of the convex lens, which is given as a great secret, in place of the concave speculum of the first edition, is not so clearly described as by Barbaro; the addition of the concave speculum is proposed for making the images larger and clearer, and also for making them erect, but no details are given.
In his later book, Dioptrice (1611), he fully discusses refraction and the use of lenses, showing the action of the double convex lens in the camera obscura, with the principles which regulate its use and the reason of the reversal of the image.
The Notonectidae, or " water-boatmen " (q.v.) have convex ovoid bodies admirably adapted for aquatic life.
dogs, wolves, jackals, &c., which constitute the genus Canis in its more restricted sense, foxes are best distinguished by the circumstance that in the skull the (postorbital) projection immediately behind the socket for the eye has its upper surface concave, with a raised ridge in front, in place of regularly convex.
convex glass lens (for which the velocity of light is less than for the air), so sound ought to be made to converge by passing.
through a convex lens formed of carbonic acid gas.
The pillars composing it are close-fitting and for the most part somewhat irregular hexagons, made up of articulated portions varying from a few inches to some feet in depth, and concave or convex at the upper and lower surfaces.
The " knoppern " galls of Cynips polycera, Gir., are cones having the broad, slightly convex upper surface surrounded with a toothed ridge.
Thus the body becomes umbrellashaped, the concave side representing the peristome, and the convex side the column, of the polyp. Hence the tentacles are found at the edge of the umbrella, and the hypostome forms usually a projecting tube, with the mouth at the extremity, forming the manubrium or handle of the umbrella.
The direction of the folds in the older series is in Iviza nearly west to east, in Majorca south-west to north-east, and in Minorca south to north, thus forming an arc convex towards the south-east.
The umbrella-like body bears a circle of tentacles at the edge, whereby the body can be divided into a convex exumbrella or exumbral surface and a concave subumbrella or subumbral surface.
This head-shield is succeeded by a varying number of free segments, each of which consists of a medium convex tergal piece and a pair of arched lateral plates, the pleura, of which there is one on each side.
One flagellum is entirely free and directed forwards; the other at once turns backwards and is attached to the convex or dorsal side of the body for the greater part of its length.
One of its peculiarities is the convex profile of the face, the forehead being prominent and the nostrils sunk in, the nose itself extremely small, and the lower lip projecting from the upper.
The cuesta would be straight from east and west if the slant of the strata were uniformly to the south; but the strata are somewhat warped, and hence the course of the cuesta is strongly convex to the north in the middle, gently convex to the south at either end.
The morainic belts are arranged in groups of concentric loops, convex southward, because the ice sheets advanced in lobes along the lowlands of the Great Lakes; neighboring morainic loops join each other in re-entrants (north-pointing cusps), where two adjacent glacial lobes came together and formed their moraines in largest volume.
Flanking strata are even better exhibited in the Bighorn Mountains, the front range of northern Wyoming, crescentic in outline and convex to the northeast, like the Laramie Range, but much higher; here heavy sheets of limestone arch far up towards the range crest, and are deeply notched where consequent streams have cut down their gorges.
As a result, the isotherms of July are strongly convex poleward as they cross the United States, the isotherm of 70 Sweeping up to the northern boundary in the north-west, and the heat equator leaping to the overheated deserts of the south-west, where the July mean is over 90.
Conversely, the isotherms of January are convex southward, with a monthly mean below 32 in the northern third of the interior, and of zero on the mid-northern boundary.
Cyrtodontidae.-Extinct; shell equivalve and inequilateral, short, convex.
3, e) and the outer lobe is convex and soft.
Some of the slightly cloudy Ceylon sapphires, usually of greyish-blue colour, display when cut with a convex face a chatoyant luminosity, sometimes forming a luminous star of six rays, whence they are called "star sapphires".
The upper half or body of the uterus is somewhat triangular with its base upward, and has an anterior surface which is moderately flat, and a posterior convex.
is represented in all the three great continents of the Old World, and extends as far east as Flores and Celebes, the skull is swollen and convex, the spines are cylindrical, and the tail is short and covered with spines and slender-stalked open quills.
The most remarkable feature of the genus is, however, the extraordinary development of the zygomatic arches of the skull, which are enormously expanded vertically, forming great convex bony capsules on the sides of the face, enclosing on each side a large cavity lined with mucous membrane internally, and communicating by a small opening with the mouth.
He now compared the spiritual and bodily sides of a man to the concave and convex sides of a circle, as inner and outer sides of the same process, which is psychical as viewed from within and physical as viewed from without.
d 4 L, on both sides, KuprO, convex) or cissoidal (Gr.
This, between the Dauphine and the borders of Hungary, forms a broad band convex towards the north, while most of the valleys lie between the directions west to east and south-west to north-east.
From the above account it will at once appear that between the convex and the concave margins of the Alpine chain there is a striking difference.
The ground should be excavated to the depth of a foot or more - the bottom being made firm and slightly concave, so that it may slope to the centre, where a drain should be introduced; or the bottom may be made convex and the water allowed to drain away at the sides.
The bottom crock is made from a piece of a broken garden pot, and is laid with the convex side upwards; then comes a layer of irregular pieces of crock of various sizes, about i in.
Another simple case is where the plane or slightly convex surface of the stroma rises at its margins and overgrows the sporogenous hyphal ends, so that the spores, asci, &c., come to lie in the depression of a cavity - e.g.
Sometimes they are nearly in a circle at the same level, remaining flat or only slightly convex externally, and placed so as to touch each other by their edges, thus giving rise to valvate vernation.
The numerous stamens surround the ovary, which is composed of 4 to 16 carpels and is surmounted by a flat or convex rayed disk bearing the stigmas.
The Canary Islands resemble a roughly-drawn semicircle, with its convex side facing southwards, and with the island of Hierro detached on the south-west.
The result is that the object assumes a smooth concave and convex shape, without the thickness of the metal becoming reduced.
Giambattista della Porta, in his Magia Naturalis, printed in 558, makes the following remarkable statement: "If you do but know how to join the two (viz.,'the concave and the convex glasses) rightly together, you will see both remote and near objects larger than they otherwise appear, and withal very distinct."
Kepler, who examined Porta's account of his concave and convex lenses by desire of his patron the emperor Rudolph, declared that it was perfectly unintelligible.
chap. 21) of Leonard Digges 1 (originally published by his son Thomas in 1571, and again in 1591): - "Marvellous are the conclusions that may be performed by glasses concave and convex, of circular and parabolic forms, using for multiplication of beams sometime the aid of glasses transparent, which, by fraction, should unite or dissipate the images or figures presented by the reflection of other."
All the original Dutch telescopes were composed of a convex and a concave lens, and telescopes so constructed do not invert.
The inverting telescope, composed of two, convex lenses, was a later invention; still it is not impossible that the original experiment was made with two convex lenses.
In his Saggiatore Galileo states that he solved the problem of the construction of a telescope the first night after his return to Padua from Venice, and made his first telescope next day by fitting a convex lens in one extremity of a.
Kepler first explained the theory and some of the practical advantages of a telescope constructed of two convex lenses in his Catoptrics (1611).
The triple object-glass, consisting of a combination of two convex lenses of crown glass with a concave flint lens between them, was introduced in 1765 by Peter, son of John Dollond, and many excellent telescopes of this kind were made by him.
of an eye-lens, concave or convex, by which the image so formed.
r shows the course of the rays when the eye-lens is convex (or positive), fig.
The substitution of a positive or negative eye-piece for the simple convex or concave eye-lens, and of an achromatic object-glass for the simple object-lens, transforms these, early forms into the modern achromatic telescope.
The Cassegrain telescope differs from the Gregorian only in the substitution of a convex hyperboloidal mirror for a concave ellipsoidal mirror as the small speculum.
21 (d); in this case a convex mirror of different curvature is employed, the equivalent focus of the combination being 80 ft.
Again, the locus of G is an arc of an ellipse whose centre is in the intersection of the planes; since this arc is convex upwards the equilibrium is unstable.
Further, it is known from the theory of roulettes that the locus of G will be concave or convex upwards according as cos 4, 1 i ~p~p (8)
For a smaller pitch-circle the flanks would be convex and in- curved or under-cut, which would be inconvenient; therefore the C smallest wheel of a set should FIG.
Nearly Epicycloidal Teeth: Williss Method.To facilitate the drawing of epicycloidal teeth in practice, Willis showed how to approximate to their figure by means of two circular arcsone concave, for the flank, and the other convex, for the faceand each having for its radius the mean radius of curvature of the epicycloidal arc. \Villiss formulae are founded on the following properties of epicycloids Let R be the radius of the pitch-circle; r that of the describing circle; 8 the angle made by the normal TI to the epicycloid at a given point T, with a tangent-to the circle at Ithat is, the obliquity of the action at T.
Screws.The figure of a screw is that of a convex or concave cylinder, with one or more helical projections, called threads, winding round it.
Convex and concave screws are distinguished technically by the respective names of male and female; a short concave screw is called a nut; and when a screw is spoken of without qualification a convex screw is usually understood.
A pair of convex screws, each rotating about its axis, are used as an elementary combination to transmit motion by the sliding contact of their threads.
Between the concave spherical surfaces of those cups is placed a steel 0 ball, being either a complete sphere or a lens having convex surfaces of a somewhat less radius p i than the concave surfaces of the cups.
The ventral side of the body in the atrial region is broad and convex, so that the body presents the appearance of a spherical triangle in transverse section, the apex being formed by the dorsal fin and the angles bordered by two hollow folds, the metapleural folds, each of which contains a continuous longitudinal lymph-space, the metapleural canal.
The two valves of the shell are unequal in size, and of different shape; the left valve is larger, thicker and more convex, and on it the animal rests in its natural state.
It is also practically independent of the curvature of the surface, although it appears from the mathematical theory that there is a slight increase of tension where the mean curvature of the surface is concave, and a slight diminution where it is convex.
When the surface is curved, the effect of the surface-tension is to make the pressure on the concave side exceed the pressure on the convex side by T (1 /R I i /R 2), where T is the intensity of the surface-tension and R 1, R2 are the radii of curvature of any two sections normal to the surface and to each other.
The film will swell out into the convex part of an unduloid, having its largest section midway between the disks, and we have to determine whether the internal pressure will be greater or less than before.
The mean curvature of these surfaces is therefore convex towards the axis.
If the mean curvature is convex towards the axis the film will move from the axis.
He solved the problem of finding the point in a convex mirror at which a ray coming from one given point shall be reflected to another given point.
As the down and up strokes run into each other, and the convex surface of the wing is always directed upwards and the concave surface downwards, it follows that the upper surface of the wing evades in a great measure the upper air, while the under surface seizes the nether air.
During the up stroke of the piston the wing is very decidedly convex on its upper surface (a b c d, A A'); its under surface (e f g h, A A') being deeply concave and inclined obliquely upwards and forwards.
His aeroplanes were variously shaped, and were, as a rule, concavo-convex, the convex surface being directed upwards.
Its general form is that of a wide crescent convex towards the north, but its shores are more irregular in outline than those of the other lakes.
Any object viewed across such an area is seen by two sets of rays: one set passing near the earth and assuming a curved path convex to the horizon, the second set more remote from the earth and concave to the horizon.
Surface drainage is usually effected by ploughing the land into convex ridges off which the water runs into intervening furrows and is conveyed into ditches.
In the Himalayan and Indian hunia sheep, the rams of which are specially trained for fighting, and have highly convex foreheads, the tail is short at birth.
A re-entrant branch not cutting itself may be everywhere convex, and it is then properly said to be an oval; but the term oval may be used more generally for any re-entrant branch not cutting itself; and we may thus speak of a once indented, twice indented oval, &c., or even of a cuspidate oval.
There are two non-singular kinds, the one with, the other without, an oval, but each of them has an infinite (as Newton describes it) campaniform branch; this cuts the axis at right angles, being at first concave, but ultimately convex, towards the axis, the two legs continually tending to become at right angles to the axis.
The Caribbean coast-line is concave, the Pacific deeply convex.
The postseptal coelom is partially divided by a ventral mesentery which is attached along the entire length of the convex.
A cissoid angle is the angle included between the concave sides of two intersecting curves; the convex sides include the sistroid angle.
The capsule opens transversely by a convex lid and contains numerous seeds.
We shall merely note some points which are frequently overlooked: (i) the crescent phase of the moon is shown only when the moon is less than 90° from the sun; (2) the bright convex outline of the crescent is then on the side toward the sun, and that the moon is seen full only when in opposition to the sun, and therefore rising about the time of sunset.
The fracture is perfectly conchoidal, so that blows with a hammer detach flakes which have convex, slightly undulating surfaces.
On its outer or convex side the folded belt is clearly defined by a depression which is generally filled by modern deposits.
If the figure be entirely to one side of any face the polyhedron is said to be " convex, " and it is obvious that the faces enwrap the centre once; if, on the other hand, the figure is to both sides of every face it is said to be concave, " and the centre is multiply enwrapped by the faces.
Light from an extended source passes after polarization through two convex systems of lenses, between which the crystalline plate is placed, and is then received in an eyepiece furnished with an analyser.
The glenoid surface for the articulation of the mandible is greatly extended transversely, concave from side to side, convex from before backwards in front, and hollow behind, and is bounded posteriorly at its inner part by a prominent post-glenoid process.
The condyle is greatly elevated above the alveolar border; its articular surface is very wide transversely, and narrow and convex from before backwards.
The bodies of the cervical vertebrae are elongated, strongly keeled, and markedly opisthocoelous, or concave behind and convex in front.
They have their convex edge directed forwards, and their concave, or cutting edge, turned backwards.
These observations show that the outline on that portion of the light commonly seen in the morning or evening is concave instead of convex, as it would be were the cloud strictly lenticular.
Again if a small hole be made in a thin plate of metal, and a minute drop of water be inserted in it, this drop, having two convex surfaces, will serve as a still more powerful magnifier.
There is reason to believe that the magnifying power of transparent media with convex surfaces was very early known.
A convex lens of rockcrystal was found by Layard among the ruins of the palace of Nimrud; Seneca describes hollow spheres of glass filled with water as being commonly used as magnifiers.
Convex glass lenses were first generally used to assist ordinary vision as " spectacles "; and not only were spectacle-makers the first to produce glass magnifiers (or simple microscopes), but by them also the telescope and the compound microscope were first invented.
If the ordinary convex lens be employed as magnifying glass, great aberrations occur even in medium magnifications.
Thus it is possible to correct a system by combining a convex and a concave lens, if both have aberrations of the same amount but of opposite signs.
If there are numerous flowers on a flattened, convex or slightly concave receptacle, having either very short pedicels or none, a a (From Strasburger's Lehrbuch der Botanik, by permission of Gustav Fischer.) FIG.
In the American button-bush the heads are globular, in some species of teazel elliptical, while in scabious and in composite plants, as sunflower, dandelion, thistle, centaury and marigold, they are somewhat hemispherical, with a flattened, slightly hollowed, or convex disk.
Application of configuration spaces to the theory of convex billiards: 4. Farber, Michael Topology of billiard problems.
boletus edulis is brown with a convex to shield shaped cap 8-20cm across and the stem is bulbous at the base.
concave on one side and convex on the other.
At other times the path is either concave or convex to the solar equator.
convergest familiar lens is the magnifying glass which is an example of a convex or converging lens.
The convex hull is the minimum area convex polygon which will entirely contain the set.
The convex hull is the minimal convex hull is the minimal convex covering of an object.
convex lens has a focal length of 150 mm.
The artist has painted himself in a convex mirror on a specially prepared convex mirror on a specially prepared convex panel.
convex subset of R n.
Upper surface dark gray, nearly black in places, slightly convex, nearly flat near the margin.
A strongly convex cone is one which contains no lines through the origin.
If the egg yolk is not convex and firm, don't consume the egg.
The domed disk is plano-convex, (sometimes double convex, (sometimes double convex) with a smaller radius bulge atop the convex side.
Varied Carpet beetles and Wooly bears The adult varied Carpet Beetle is between 2 to 4mm long with a highly convex body.
convex in shape like many cases out there.
A convex lens has a focal length of 150 mm.
The convex hull is the minimal convex covering of an object.
The M2 mirror is a convex hyperbolic mirror with an external diameter slightly in excess of 1 meter.
mouldingthe very edge face of the bench end is a half-round convex molding.
About the " flat " description, I thought this to mean not oblong or convex in shape like many cases out there.
How would you set about deciding whether they defined a convex polygon?
In origami this term is often misused to mean any star-like form produced by adding pyramids to the faces of a convex polyhedron.
To see this let B be a convex subset of R n.
The conventional domed tweeter is convex, with a voice coil of the same diameter.
inner lobe of large and convex; three ocelli ' left maxilla).
Every bowl must have a certain amount of bias, which was formerly obtained by loading one side with lead, but is now imparted by the turner making one side more convex than the other, the bulge showing the side of the bias.
The body is sub-cylindrical or somewhat convex above, flatter below, broad and oval in front and narrowed and elongate behind.
The island is long and narrow, somewhat in the form of an irregular crescent, convex toward the N.
The typical Egyptian obelisk is an upright monolith of nearly square section, generally to diameters in height, the sides slightly convex, tapering upwards very gradually and evenly, and terminated by a pyramidion whose faces are inclined at an angle of 60Ã‚°.
In the first half of the 18th century a plough with a short convex mould-board of wood was introduced from the Netherlands into England and, as improved at Rotherham in Yorkshire, became known as the Rotherham plough and enjoyed considerable vogue.
Rays from external objects are first refracted at the convex surface a b, then totally reflected at the plane surface a c, and finally refracted at the concave surface b c (fig.
From Hooke's Posthumous Works (1705), p. 127, we find that in one of the Cutlerian lectures on Light delivered in 1680, he illustrated the phenomena of vision by a darkened room, or perspective box, of a peculiar pattern, the back part, with a concave white screen at the end of it, being cylindrical and capable of being moved in and out, while the fore part was conical, a double convex lens being fixed in a hole in front.
Again, to obviate the necessity for excessive convergence of the eyes so common in hypermetropia, the centre of the pupil should be placed outside the centre of the corrective convex lenses; these will then act as prisms with their bases inwards.
Convex spectacles were invented (see Light) towards the end of the 13th century, perhaps by Roger Bacon.
Valz pointed out that the other optical conditions could be equally satisfied if the divided lens were made concave instead of convex, with the advantage of giving a larger field of view (Monthly Notices, vol.
Some of the slightlycloudy Ceylon sapphires, usually of greyish-blue colour, display when cut with a convex face a chatoyant luminosity, sometimes forming a luminous star of six rays, whence they are called "starsapphires" (see Asteria).
For spectroscopic purposes the Cassegrain form has peculiar advantages, because in consequence of the less rapid convergence of the rays after reflection from the convex hyperboloidal mirror, the equivalent focus can be made very great in comparison with the length of the tube.
The catenaries which lie between the two whose direction coincides with the axis of revolution generate surfaces whose radius of curvature convex towards the axis in the meridian plane is less than the radius of concave curvature.
The catenaries which lie beyond the two generate surfaces whose radius of curvature convex towards the axis in the meridian plane is greater than the radius of concave curvature.
We shall merely note some points which are frequently overlooked: (i) the crescent phase of the moon is shown only when the moon is less than 90Ã‚° from the sun; (2) the bright convex outline of the crescent is then on the side toward the sun, and that the moon is seen full only when in opposition to the sun, and therefore rising about the time of sunset.
Any solid or liquid transparent medium of lenticular form, having either one convex and one flat surface or two convex surfaces whose axes are coincident, may serve as a " magnifier," the essential condition being that it shall refract the rays which pass through it so as to cause widely diverging rays to become either parallel or but slightly divergent.
The floral axis may be shortened, assuming a flattened, convex or concave form, and bearing numerous flowers, as in the arti choke, daisy and fig (fig.
In the more primitive types of flowers the torus is more or less convex, and the series of organs follow in regular succession, culminating in the carpels, in the formation of which the growth of the axis is closed (fig.
In many of the flowers described by Mr Wieland the structure is identical in essential features with that of the female flowers of Bennettites Gibsonianus described by Carruthers and by Solms-Laubach, and with that of a French Liassic species described by Lignier: the whole consists of a convex receptacle bearing mature seeds at the tips of pedicels associated with interseminal scales (fig.
The Carnival logo is a simple reverse C character, with a white reverse C framed with blue on the concave (left) side and red on the convex (right) side.
He also wrote down information about looking through a transparent surface with the convex side toward the eye.
Prior to his invention around 1760, the convex and concave lenses (farsighted and nearsighted lenses respectively) were worn separately.
In fact, convex lenses used to correct farsightedness came along nearly 300 years before the concave lenses to correct nearsightedness did.
These glasses contained convex lenses (lenses that bend outwards) that could correct farsightedness and the worsening of vision often seen as individuals age.
You won't miss a moment with features like Luminescent Hour-Markers And Hand-Applied 12 Numeral, unique Convex Scratch-Resistant Sapphire Crystal, and modern Tachometer.
The Convex scratch-resistant sapphire crystal Case cut from a solid steel block magnificently designed, Unidirectional turning bezel with fluted rim, in fine-brushed or polished steel with engraved dive-time scale gives a suave look.
This Convex Grid watche by Cartier is highly modern in style and functionality.
They also feature a polished stainless steel face with convex beveled grids, luminous hands and markers, a Cabochon crown, unidirectional bezel and a calendar.
Color the convex (back) side of a paper plate with the orange and yellow crayons.
The basement storey has the same number of faces formed into convex flutes which are alternately angular and semicircular.
The word usage examples above have been gathered from various sources to reflect current and historial usage. They do not represent the opinions of YourDictionary.com.