If one end is sharply pressed in, a compression can be seen running along the spring.
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 compression members are of timber, except the struts and bottom chord panels next the river piers, which are of steel.
The concrete not only affords much of the strength to resist compression, but effectively protects the steel from corrosion.
If A t A, are the cross sections of the tension and compression flanges or chords, and h the distance between their mass centres, then on the assumption that they resist all the direct horizontal forces the total stress on each flange is Ht=H,=M/h and the intensity of stress of tension or compression is f t = M/Ath, f c = M/Ach.
The fact that a solid body in its natural state is capable both of compression and of dilatation indicates that the molecules of the body must not be supposed to be fixed rigidly in position relative to one another; the further fact that a motion of either compression or of dilatation is opposed by forces which are brought into play in the interior of the solid suggests that the position of rest is one in which the molecules are in stable equilibrium under their mutual forces.
Thus a push or a compression of the X air is transmitted onwards in the direction OX.
The term Pv/V added up for a complete wave vanishes, for P/V is constant and Zv=o, since on the whole the compression equals the extension.
20 shows a Fink truss, a characteristic early American type, with cast iron compression and wrought iron tension members.
Hard steel, if used at all, is used only for compression members, in which there is less risk of flaws extending than in tension members.
For compression members the shearing area of rivets in butt-joints was made half the useful section of plate in compression.
For practical purposes it is accurate enough to consider the booms or chords as carrying exclusively the horizontal tension and compression and the web as resisting the whole of the vertical and, in a plate web, the equal horizontal shearing forces.
The compression members being generally of timber and the tension members of steel.
Thayer, with other essays, 1889), originally a lecture, and in spite of the compression due to its form, up to that time probably the ablest defence, based on external evidence, of the Johannine authorship, and certainly the completest treatment of the relation of Justin Martyr to this gospel.
The device employed for this purpose is known as the water-packer, and consists in its simplest form of an india-rubber ring, which is applied between the tubing and the well-casing, so that upon compression it makes a tight joint.
From his views on centrifugal force he deduced the oblate figure of the earth, estimating its compression, however, at little more than one-half its actual amount.
The specific gravity of cast gold varies from 18.29 to 19.37, and by compression between dies the specific gravity may be raised from 19.37 to 19.41; by annealing, however, the previous density is to some extent recovered, as it is then found to be 19.40.
Transmitted onwards following the compression which has already gone out.
Or we may take it as representing the pressure - excess over the normal pressure in compression, defect from it in extension.
The consequence is that the compression travels rather faster, and the extension rather slower, than at the speed found above.
In both England and America in early braced bridges cast iron, generally in the form of tubes circular or octagonal in section, was used for compression members, and wrought iron for the tension members.
In compression boom, 7 o tons in tension boom, 5 o tons in vertical struts, 6.5 tons in diagonal ties, 8 o tons in wind bracing, and 6.5 tons in cross and rail girders.
The value of H is equal to the maximum tension on the bottom flange, or compression on the top flange, of a girder of equal span, equally and similarly loaded, and having a depth equal to the dip of the suspension bridge.
The principal differences are the complication of the ciliated band, the absence of the excretory organ, the great lateral compression of the body, the possession of a pair of shells protecting the sides, the presence of an organ known as the "pyriform organ," and the occurrence of a sucker in a position corresponding with the depression seen between (m) and (a) in fig.
The opposite axes are connected with springs which are kept in compression by tension of the rope in drawing but come into action when the pull is released, the side axes then biting into wooden guides or gripping those of steel bars or ropes.
The brine is cooled in a tank filled with spiral pipes, in which anhydrous ammonia, previously liquefied by compression, is vaporized in vacuo at the atmospheric temperature by the sensible heat of the returncurrent of brine, whose temperature has been slightly raised in its passage through the circulating tubes.
For masonry, brick or concrete the arch subjected throughout to compression is the most natural form.
The function of the flanges is to resist a horizontal tension and compression distributed practically uniformly on their cross sections.
In such rolling operations the girder is subjected to straining actions different from those which it is intended to resist, and parts intended for tension may be in compression; hence it may need to be stiffened by timber during rolling.
Then dp/dz=kdp/dz = P, = Poe ik, p - po= kpo(ez Ik -1); (16) and if the liquid was incompressible, the depth at pressure p would be (p - po) 1po, so that the lowering of the surface due to compression is ke h I k -k -z= 1z 2 /k, when k is large.
O tons in verticals and long compression members.
The weight load was pushing downwards, causing pressure on the strut.
Jupiter was measured on eleven nights in the months of June and July 1794; from these measures Schur derives the values 35"39 and 37".94 for the polar and equatorial diameter respectively, at mean distance, corresponding with a compression 1/14.44.
Since the forces called into play by an extension or compression of the material are proportional to the cross-section, it follows that if we consider any case and then another case in which, with the same longitudinal disturbance, the cross-section is doubled, the force in the second case is doubled as well as the mass to be moved.
The suspension bridge dispenses with the compression member required in girders and with a good deal of the stiffening required in metal arches.
Of the internal stresses, which balance the external forces, shows that most of the material should be arranged in a top flange, boom or chord, subjected to compression, and a bottom flange Or chord, subjected to tension.
In this category may be placed head-deformation, which reached its extreme development among the Indians of North-West America and the ancient Peruvians; foot-constriction as practised by the Chinese; tooth-chipping among many African tribes; and waist-compression common in Europe at the present day.
BENZENE, C 6 H 6, a hydrocarbon discovered in 1825 by Faraday in the liquid produced in the compression of the illuminating gas obtained by distilling certain oils and fats.
The figure shows that when the curve of displacement slopes down in the direction of propagation there is compression, and the pressure is above the normal, and that when it slopes up there is extension, and the pressure is below the normal.
It is obvious that the nodes are alternately in compression and extension, or vice versa, and that for 4X on each side of a node the motion is either to it on both sides or from it on both sides.
Bridges may be classed as arched bridges, in which the principal members are in compression; suspension bridges, in which the principal members are in tension; and girder bridges, in which half the components of the principal members are in compression and half in tension.
In the iron cylinder and ovoid, which expanded when magnetized, compression caused a diminution of magnetization; in the nickel rod, which contracted when magnetized, pressure was attended by an increase of magnetization.
Ewing has also examined the effects produced by longitudinal compression upon the susceptibility and retentiveness of nickel, and found, as was to be expected, that both were greatly increased by pressure.
In the Greek school at Alexandria, which flourished under the auspices of the Ptolemies, the first attempts were made at the construction of hydraulic machinery, and about 120 B.C. the fountain of compression, the siphon, and the forcing-pump were invented by Ctesibius and Hero.
(3) Expansion or compression at constant temperature, represented by curves called Isothermals, such as BC, AD, the form of which depends on the nature of the working sub stance.
Whilst alcohol is applied in motor engines in a similar manner to petrol, its vapour mixed with a proper proportion of air being drawn into the cylinder where it is compressed and ignited, it cannot be used with maximum efficiency by itself in engines such as are fitted to modern motors because it requires a higher degree of compression than petrol engines are usually designed to stand, and also because, unless special arrangements are made, a motor engine will not start readily from the cold with alcohol alone.
When the value of dyldx is not very small E is no longer constant, but is rather greater in compression and rather less in extension than -yP. This can be seen by considering that the relation between p and is given by a curve and not by a straight line.
Effects Of Mechanical Stress Upon Magnetization The effects of traction, compression and torsion in relation to magnetism have formed the subject of much patient investigation, especially at the hands of J.
In China his mention of Canton by the name of Censcolam or Censcolam (Chin-Kalan), and his descriptions of the custom of fishing with tame cormorants, of the habit of letting the finger-nails grow extravagantly, and of the compression of women's feet, are peculiar to him among the travellers of that age; Marco Polo omits them all.
(4) Expansion or compression under the condition of heat-insulation, represented by curves called Adiabatics, such as BAZ or CDZ', which are necessarily steeper than the isothermals.