The irregularity of spacing has thus the effect of a convex lens, which accelerates the marginal relatively to the central rays.
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.
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.
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.
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.
Convex spectacles were invented towards the end of the 13th century.
32), are a large family of beetles, well known by their rounded convex bodies, usually shining and hairless.
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.
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 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.
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.
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.
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.
He described the reflecting goniometer in 1809 and the camera lucida in 1812, provided microscopists with the "Wollaston doublet," and applied concavo-convex lenses to the purposes of the oculist.
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.
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.
The white perianth is six-parted, the outer three segments being larger and more convex than the inner series.
If the trapezette, as seen from above, is everywhere convex or everywhere concave, the true area lies between C 1 and T1.
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.
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.
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.
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.
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.
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.
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 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.
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.
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.
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.
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.
- Biconcave, biconvex and concavo-convex (meniscus) lenses are employed in ophthalmic practice in the treatment of errors of refraction.
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.
Ehrenberg), a genus of lobose Rhizopoda, characterized by a chitinous plano-convex shell, the circular aperture central on the fiat ventral face, and more than one nucleus and contractile vacuole.
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.
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.
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.
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.
The Notonectidae, or " water-boatmen " (q.v.) have convex ovoid bodies admirably adapted for aquatic life.