How to use Concave in a sentence
Concave Lenses are used in the treatment of myopia or shortsight.
He refers to Maurolycus' work with concave specula.
Rayleigh points out that this clinging of the sound to the surface of a concave wall does not depend on the exactness of the spherical form.
The facial line is concave.
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.Advertisement
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.
The dried insect has the form of irregular, fluted and concave grains, of which about 70,000 go to a pound.
A marine inlet where the coastline usually follows a concave curve between rocky headlands.
The concave dorsal fin begins above the base of the ventral fins.
Others look best when the blush is applied just under the apples of their cheeks, in the concave of the cheekbone.Advertisement
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.
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.
Franklin just took the two, almost 200 years after the concave lenses were designed for near vision, and created an eyeglass that housed both types.
The use of concave lenses (lenses that depress inward) to correct nearsightedness is attributed to Nicholas of Cusa and the thought that specific lenses were required to ease various problems with vision prevailed for centuries.Advertisement
Fingernails may be small and concave with pitting, ridges, splits, and/or discoloration.
These are also called concave, angle, stacked, and wedge bobs.
To make a valley fold, you should fold one section of the paper up and over the other section - creating a concave crease.
The theater is also much different than a standard theater, where the screen is actually slightly concave.
It is common for people with scoliosis to take in less air on the concave side of the spine.Advertisement
By focusing on the breath and directing it into the concave side of the spine, the muscles stretch and increase lung capacity.
On the concave, or front, side of the paper plate, arrange the handprints in a circle with the fingers pointing out, like rays of sunshine.
On the other hand, to produce convergence with water or hydrogen gas, in both which the velocity of sound exceeds its rate in air, the lens ought to be concave.
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.Advertisement
Usually the under or concave edge of the arc is the more clearly defined, and adjacent to it the sky often seems darker than elsewhere.
If an object has to be beaten into concave form from a flat thin sheet, the outer portions must be hammered until they occupy smaller dimensions than on the flat sheet.
The result is that the object assumes a smooth concave and convex shape, without the thickness of the metal becoming reduced.
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.
All the original Dutch telescopes were composed of a convex and a concave lens, and telescopes so constructed do not invert.
James Gregory, in his Optica Promota (1663), discusses the forms of images and objects produced by lenses and mirrors, and shows that when the surfaces of the lenses or mirrors are portions of spheres the images are curves concave towards the objective, but if the curves of the surfaces are conic sections the spherical aberration is corrected.
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.
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.
A A and B B are concave mirrors having a common axis and their concavities facing each other.
A A is a concave mirror whose axis is a a.
Both mirrors are usually concave; if plane, a concave lens is placed immediately before them.
In the rat-kangaroos, or kangaroo-rats, as they are called in Australia, constituting the sub-family Potoroinae, the first upper incisor is narrow, curved, and much exceeds the others in length; the upper canines are persistent, flattened, blunt and slightly curved, and the first two premolars of both jaws have large, simple, compressed crowns, with a nearly straight or slightly concave free cutting-edge, and both outer and inner surfaces usually marked by a series of parallel, vertical grooves and ridges.
He did not, however, enter into the explanation of particular phenomena, as this had been done already by Laplace, but he pointed out to physicists the advantages of the method of Segner and Gay Lussac, afterwards carried out by Quincke, of measuring the dimensions of large drops of mercury on a horizontal or slightly concave surface, and those of large bubbles of air in transparent liquids resting against the under side of a horizontal plate of a substance wetted by the liquid.
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 mean curvature of these surfaces is, therefore, concave towards the axis.
If the mean curvature is concave towards the axis the film will tend to approach the axis.
So closely allied are these two fishes that their distinctness can be proved only by an examination of the gill-apparatus, the allis shad having from sixty to eighty very fine and long gill-rakers along the concave edge of the first branchial arch, whilst the twaite shad possesses from twenty-one to twenty-seven stout and stiff gill-rakers only.
That which flows from the lower incisions is often collected on tiles or on a concave piece of the prickly pear (Opuntia), but is less crystalline and more glutinous, and is less esteemed.
The muscular system of the Scyphomedusae is developed on the subumbral surface as a system of circularly disposed fibres which by their contraction make the umbrella more concave and diminish its FIG.
It is, as a rule, deeply concave on its FIG.
It only remains to be stated that the wing acts as a true kite, during both the down and the up strokes, its under concave or biting surface, in virtue of the forward travel communicated to it by the body of the flying creature, being closely applied to the air, during both its ascent and its descent.
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.
This is due to a stratum of hot air at some distance above the sea level, the rays of light near the horizon being practically horizontal, while those at greater elevations are fairly concave.
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 anterior part of the palate is composed of mucous membrane tightly stretched over the flat or slightly concave bony layer which separates the mouth from the nasal passages, and is generally raised into a series of transverse ridges, which sometimes, as in ruminants, attain a considerable development.
The arc being struck in the usual way between two carbons, a concave mirror, placed close behind it, caused a large part of the radiation to be directed through an aperture in the camera and concentrated to a focus outside.
The Caribbean coast-line is concave, the Pacific deeply convex.
A cissoid angle is the angle included between the concave sides of two intersecting curves; the convex sides include the sistroid angle.
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.
When the rings are coloured symmetrically with respect to two perpendicular lines the acute bisectrix and the plane of the optic axes are the same for all frequencies, and the colour for which the separation of the axes is the least is that on the concave side of the summit of the hyperbolic brushes.
With a biaxal plate perpendicular to the optic axis in the diagonal position, the hyperbolic brush becomes an hyperbolic line and the rings are expanded or contracted on its concave side, with a positive plate, according as the plane of the optic axes is parallel or perpendicular to the axis of the quarter-wave plate, the reverse being the case with a negative plate.
In the greater part of the Ebro basin the heat of summer is even more intense, The treeless mostly steppe-like valley with a brightcoloured soil acts like a concave mirror in reflecting the suns rays and, moreover, the mountains and highlands by which the valley is enclosed prevent to a large extent the access of winds.
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 bodies of the cervical vertebrae are elongated, strongly keeled, and markedly opisthocoelous, or concave behind and convex in front.
The bones of the legs should be short, flat, clean and hard; the feet large, with hoofs deep and concave below.
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.
Descartes (Dioptrique, 1637) describes microscopes wherein a concave mirror, with its concavity towards the object, is used, in conjunction with a lens, for illuminating the object, which is mounted on a point fixing it at the focus of the mirror.
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.
The possibilities of illuminating with a concave mirror seem a little more favourable.
As a rule a concave mirror of similar aperture is fitted on the other side of the plane mirror.
With the concave mirror an image of the source of light can be thrown upon the object.
The distance of the concave mirror from the stage plate is about equal to its focal length.
This was a concave mirror, pierced in the middle, fixed to the objective, and directed towards the object and with such a FIG.
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.
If the margins of such a receptacle be developed upwards, the centre not developing, a concave receptacle is formed, which may partially or completely enclose a number of flowers that are generally unisexual.
The limb of the petal may be flat or concave, or hollowed like a boat.
He was little more than five feet high; his breast was almost concave, and, like Schleiermacher, he was deformed in the right shoulder.
On less well finished, slightly concave side are remains of c.
If the neck is too concave (action too high ), turn the truss rod nut clockwise to remove excess relief.
The core plug was positioned in its hole and flattened out - not concave - with a dolly about 1.5 " diameter.
At other times the path is either concave or convex to the solar equator.
At last the world seemed no longer a sphere but flat, and then concave.
Clearly as society gets bigger - the ppf gets further out - and, in general, becomes more smoothly concave.
The flukes are broad, do not have a median notch, and have concave trailing edges.
These changes have been described as follows " right bundle branch block with J point elevation and concave st elevation " .
For effective examination it is necessary for the oil to form a concave meniscus on the surface of the hole to be examined.
Tail flukes are pointed at the tips with a concave trailing edge and a deep median notch.
In both species. the male can be recognized by the longer, narrower and more pointed tail some males have a concave plastron.
This was cut by 423, a smaller, round, steep-sided posthole with a concave base.
The ship on the left has a concave prow with a projecting forefoot.
The radiation passing out from an opening in the furnace falls upon a concave mirror in a telescope and is focused upon a thermoelectric couple.
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.
By introducing the concave grating which (see Diffraction Of Light, § 8) allows US to dispense with all lenses, Rowland produced a revolution in spectroscopic measurement.
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.
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.
There is usually a short gap between the canine and first premolar; the upper molars are short-crowned and transitional between the bunodont (tubercular) and selenodont (crescentic) types, with two outer concave tubercles and two inner conical ones; while the lower molars are crescentic, with three lobes in the last of the series..
Nearly related is the extinct family Lophiodontidae (inclusive of the American Helaletidae), in which both the upper and lower first premolar may be absent, while the upper molars present a more rhinoceros-like form, owing to the lateral compression and consequent lengthening of the outer columns, of which the hinder is bent somewhat inwards and is more or less concave externally, thus forming a more complete outer wall.
The flowers have a hollow tube at the base bearing at its free edge five sepals, an equal number of petals, usually concave or spoon-shaped, pink or white, and a great number of stamens.
Rowland to his brilliant invention of concave gratings, by which spectra can be photographed without any further optical appliance.
In Rowland's dividing engine the screws were prepared by a special process devised by him, and the resulting gratings, plane and concave, have supplied the means for much of the best modern optical work.
The slopes of the position towards the Austrians now took on the usual concave section, and from the crest of the ridge every movement could be seen for miles.
Subsequently the digging plough came into vogue; the share being wider, a wider furrow is cut, while the slice is inverted by a short concave mould-board with a sharp turn which at the same time breaks up and pulverizes the soil after the fashion of a spade.
He seems to have been well acquainted with the projection of images of objects through small apertures, and to have been the first to show that the arrival of the image of an object at the concave surface of the common nerve - or the retina - corresponds with the passage of light from an object through an aperture in a darkened place, from which it falls upon a surface facing the aperture.
He also had some knowledge of the properties of concave and convex lenses and mirrors in forming images.
His arrangement of concave and plane mirrors, by which the realistic images of objects inside the house or in the street could be rendered visible though intangible, there alluded to, may apply to a camera on Cardan's principle or to a method of aerial projection by means of concave mirrors, which Bacon was quite familiar with, and indeed was known long before his time.
The account is not very clear, but seems to imply the use of a concave mirror rather than a lens, which might be suggested by the word orbem.
He discloses as a great secret the use of a concave speculum in front of the aperture, to collect the rays passing through it, when the images will be seen reversed, but by prolonging them beyond the centre they would be seen larger and unreversed.
The lens used by Barbaro was an ordinary convex or old man's spectacle-glass; concave, he says, will not do.
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.
He describes some entertaining peep-show arrangements, possibly similar to Alberti's, and indicates how the dark chamber with a concave speculum can be used for observing eclipses.
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.
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.
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.
The vapour pressure-composition curve will now be concave to the axis of composition, the minima corresponding to the pure components.
These prisms may be combined with concave lenses, which correct the myopia, or, since a concave lens may be considered as composed of two prisms united at their apices, the same effect may be obtained by making the distance between the centres of the concave lenses greater than that between the centres of the pupils.
All objects, therefore, which lie beyond a certain point (the conjugate focus of the dioptric system of the eye, the far point) are indistinctly seen; rays from them have not the necessary divergence to be focused in the retina, but may obtain it by the interposition of suitable concave lenses.
Concave lenses should never be used for work within the far point; but they may be used in all cases to improve distant vision, and in very short-sighted persons to remove the far point so as to enable fine work such as sewing or reading to be done at a convenient distance.
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 swiftest current te,-ids, by reason of centrifugal force, to follow the outer side of every significant curve in the channel; hence the concave bank, against which the rapid current sweeps, is worn away; thus any chance irregularity is exaggerated, and in time a series of large serpentines or meanders is developed,, the most-symmetrical examples at present being those near Greenville, Miss.
Elsewhere moderate re-entrants between the ranges have a continuous beach, concave seaward; such re-entrants afford imperfect harbourage for vessels; Monterey Bay is the most pronounced example of this kind.
In grating spectroscopes both plane and concave gratings are employed in connexion with a collimator and observing telescope.
The earliest age of civilization, which we may designate as the clay age, is marked by rude, hand-made pottery and thumb-marked bricks, flat on one side, concave on the other, gradually developing through several fairly marked stages.
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.
In most cases the surface is concave towards the system.
If the trapezette, as seen from above, is everywhere convex or everywhere concave, the true area lies between C 1 and T1.
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.
Concave glasses were introduced soon afterwards.
The forms of roof are various, but mostly they commence in a steep slope at the top, gradually flattening towards the eaves so as to produce a slightly concave appearance, this concavity being rendered more emphatic by the tilt which is given to the eaves at the four corners.
Another character by which the European domesticated pig differs from any of the wild species is the concave outline of the frontal region of the skull.
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.
The magnetic needle may be cemented horizontally across the back of a little plane or concave mirror, about or $ in.
South of this point the coast curves outwards and is broken by peninsulas and indentations; to the north it is concave and bordered in many places by dunes and lagoons.
The weakest pair of concave lenses with which one can read clearly test types at a distance of 18 ft.
For instance, a ticking watch may be put at the focus of a large concave metallic mirror, which sends a parallel " beam " of sound to a second concave mirror facing the first.
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 shell-gland, as development proceeds, extends from its point of origin as an ectodermic thickening, which may be only slightly concave or may be deeply invaginated and then evaginated.
Lyman more recently has been able to obtain photographs as far down as 1030 A with the help of a concave grating placed in vacuo.
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.
Coelopeltis, with concave, or grooved scales; C. lacertina s.