Strainer

“ The Strainers are formed of brass or bronze plates, in which are cut a very large number of narrow slits, which gradually widen downward, so as to prevent the pulp from lodging. Each plate has about 510 slits, and several plates, connected together by bolts, constitutes the complete strainer. When in use, the strainer receives a jogging motion, which is communicated to it by means of small ratchet wheels keyed on shafts passing beneath the machine; this causes the fibres to pass more freely through the slits. ”

“ The operation of straining is repeated three or four times, until the liquor is sufficiently clear, and sometimes two strainers are employed, the one to relieve the other. An old strainer is preferred to a new one, from which the acrid quality of the fibre has not been washed by frequent use. ”

“ A convenient article where a ladle and strainer are needed is to swing a cup-shaped strainer under the bowl of a ladle as shown in the illustration. The strainer can be held in place with small bands that fit loosely over the handle. and a small tip soldered to the ladle. These will allow the ladle to be turned, leaving the strainer always in position. A large sized ladle, equipped with a strainer, is just the thing for painters to dip and strain paint, while a small one is of great assistance to the housewife for dipping and straining soups, jellies, etc. ”

“ The strainer plates have an inclination of about 1 inch in the direction of their length, and in those which are nearest to A, where the pulp enters, the slits are wider, the knots being pushed forward by the energy of the flow. The vacuum pumps, D D, are worked from the shaft E. The tubes F F are for supplying water to the plates, by which the coarser particles of the pulp are pushed forward, and the slits are thus kept clean. The strainer will pass from 18 to 20 tons of the finest paper per week. ”

“ One caution in regard to the sink: have the strainer screwed down firm. Anything that will not pass through the strainer should not go into the pipes. The hinged or loose strainer gives but little protection, as the temptation to lift it and let sediment pass through is very great. With an immovable strainer and the use, once a fortnight, of the hot solution of soda described in the chapter on “Care of Utensils,” there will be no trouble with pipes, unless it be caused by wear or freezing. ”

“ Draw a charcoal mark on the back of the strainer vertically through the centre, and mark the proper distance from the top of strainer horizontally where [Pg 45] the top of the head should come. Now move the lantern until you have it the proper distance from the strainer to make the head the size desired, and afterwards focus the features sharp and distinct, using the charcoal marks for the proper place to make the head, the vertical line coming through the centre of the face; then, seated at the end of the table, in front of the strainer, make a charcoal outline as in the former method. ”

“ The float should be so arranged that it is adjustable with reference to the lever that it contacts with.
Sixth. A gauze strainer should be placed at the gasoline inlet, and it is also advisable to have a similar strainer above the mixing chamber, beyond the throttle.
Seventh. There should be no pockets at any point in the body to hold the gasoline which might condense. ”

“ The operation of the manufacture will now be apparent. The pulp flowing from the reservoir into the lifter, and thence through the strainer, passes over a small lip to the continuous wire, being there partially compacted [72] by the shaking motion, more thoroughly so on its passage over the air boxes, receiving any desired marks by means of the dandy roller passing over the continuous felt between the first pressing rollers, then turned over to receive a corresponding pressure on the other side, and from thence off to the drying cylinders, which are heated more or less by injected steam ”

“ Support this upper shelf by screwing the four triangular braces (1” × 21⁄2” × 3”) in the corners of the shelf. Use the 8 1-inch No. 9 screws for this purpose. Saw the lower shelf out 11⁄2” on each corner and screw it on the legs at a distance of 9” from the bottom of the legs. Sandpaper but do not stain. Take a piece of flannel of the desired size and make the jelly bag in the shape of a triangle. Sew a loop of tape at each corner to hang the bag over the posts.
[Pg 24] JELLY STRAINER, NO. 2
While this jelly strainer is unique and useful in its construction it is not adjustable. ”

“ Mr. Ibotson’s improved sieve is employed to strain the paper-stuff previously to its being used in the machine above described. (see its place at B in the vat.) When the strainer is at work, a quick vertical and lateral jogging motion is given to it, by machinery similar to the joggling-screens of corn mills.
Since the lateral shaking motion of the wire-web in the Fourdrinier machine, as originally made, was injurious to the fabric of the paper, by bringing its fibres more closely together breadthwise than lengthwise, thus tending to produce long ribs, or thick streaks in its substance, Mr. ”

“ The practical difference between the two points of view is that in the one case you look for other attributes of the man besides the ability to produce a strain in the bridge, and in the other case you do not look for other attributes. So the strain theory, although not irreconcilable with the atomic hypothesis, was actually antagonistic to it, because it led men to think of the strain as distributed continuously about the surface of the charged body, rather than as radiating from definite spots or centers peppered over the surface of the body. ”

“ To derive the play of internal force, this energy function must be varied with respect to all these independent quantities; the result is elastic tractional stress in the medium across every ideal interface, together with forcive tending to displace each strain-centre, which we can consider either as resisted by extraneous constraint preventing displacement of the strain-centre, or as compensated by the reaction of the inertia of the strain-form against acceleration. ”

“ In such a chain, every strain makes an effort to bring every link into that form which it ought to have had in its first construction: and in proportion as the strain effects this, 80 far the links have been weakened, by having the particles of which they are respectively composed placed in a new order, at the expence of the corpuscular attraction exerted by these particles individually for those to which they are most contiguous. ”

“ He knew that with a little glazier's putty, an air-pump, and a few ounces of nitroglycerine he could in a quarter of an hour have that metal door blown away. Or with a strong enough current he could corrode away its lock bars by electrolysis, or with a forced acetylene flame cut away its lock-dial. But such procedure was not in keeping with either his ends or his aims. He knew that his attack could not be one of force.
He suddenly turned, crossed the studio, and stepped quietly out to the entrance door, making sure that it was locked. ”

“ In treating of the physical properties of a solid, it is necessary to consider its state of strain. A body is said to be strained when the relative position of its parts is altered, and by its state of strain is meant its state in respect to the relative position of its parts. We have hitherto considered the equilibrium of solids only in the case in which their state of strain is determined by pressures having the same values in all directions about any point. ”

“ If it is a loose object the strain will decrease as it nears the surface, but if it be the cable the strain will certainly increase, because its weight will be greater the more of it we lift off the bottom. ”

“ A suitable method depends on the fact that the strain is known round a point when we know the values of the six quantities
at the point. These are called the components of strain at (x, y, z) . The first three are stretches parallel to the axes, the other three are shearing strains. We may get an idea of the nature of these strains from two simple typical cases. 1. Let u = ex, v = 0, w = 0. This makes du/dx = e, and the other five strains zero. But we see that the displacement of every particle is perpendicular to the yz plane, and proportional to its distance from that plane. ”

“ Now in an elastic medium permeated by centres of permanent intrinsic strain, whether it be the rotational æther with its contained electrons, or an ordinary elastic solid permeated by polar strain-nuclei as described above, the specification of the strain-energy of the medium involves a mathematical function, not only of the displacement at each material point of the medium, but also of the positions of these intrinsic strain-centres which can move independently through it. ”

“ The strain-energy-function is a homogeneous quadratic function of the six strain-components, and this function may have as many as 21 independent coefficients, taking the place in the general case of the 2 coefficients which occur when the material is isotropic—a result first obtained by George Green in 1837. The best experimental determinations of the coefficients have been made indirectly by Voigt by means of results obtained in the theories of the torsion and flexure of aeolotropic bars. ”

“ It is well to get a thorough understanding of these two kinds of strains, as they are the principal strains that have to be considered in all bridge-building. There is a point between the top and bot-tom of the beam at which the character of the strain changes from compression into tension, where there is no strain at all, and the amount of strain in the beam decreases from the outside toward the center until this zero-point, or neutral plane, is reached ”

“ The effect of the pressures applied to a piece, consisting of the load and the supporting resistances, is to force the piece into a state of strain or disfigurement, which increases until the elasticity, or resistance to strain, of the material causes it to exert a stress, or effort to recover its figure, equal and opposite to the system of applied pressures. The condition of stiffness is that the strain or disfigurement shall not be greater than is consistent with the purposes of the structure ”

“ The result indicates that, when forces which produce any kind of strain are applied to a solid body and are gradually increased, the strain at any instant increases proportionally to the forces up to a stage beyond that at which, if the forces were removed, the body would completely recover its original size and shape, but that the increase of strain ceases to be proportional to the increase of load when the load surpasses a certain limit. There would thus be, for any type of strain, a limit of linear elasticity, which exceeds the limit of perfect elasticity. ”

“ It is an arbitrary distinction to call a phenomenon either physical or chemical when it happens to be on the common borderland. I have shown that when a substance is molecularly strained by light, its chemical activity is modified in consequence of the physical strain. The acted and the unacted portions will therefore be unequally attacked by a developer. In the case of a compound, the strain produced by light may cause a modification which renders it susceptible to decomposition by the action of a reducing agent. ”

“ In an exactly similar manner, we find that when we have produced an electric strain in a sheet of glass by the application of electromotive force, and if we then remove the electromotive force and connect the two tinfoil or metal surfaces by means of a piece of wire, the electric strain in the glass disappears with a series of electric oscillations; that is to say, the electric strain in the glass does not disappear or die away gradually, but it is alternately reversed, at each reversal the strain becoming less and less in magnitude. ”

“ Then, to make sure of what he had been told, he crossed the room and picked up the bar of steel that had fallen at his feet as he first entered the door. This bar he let fall so that one end would rest on the metal vault-covering and the other on the rail of copper.
There was a report, a sudden leap of flame, and the continued hissing fury of the short-circuited current, until the bar, heated to incandescence, twisted and writhed where it lay like a thing of life. He drew a deep breath, and watched it. ”

“ The condition of strain at a point in an elastic solid, is a complex accident, capable of being completely expressed by six independent accidents, which may be the three elongations of the dimensions, and the three distortions of the faces of a molecule originally cubical, or the lengths and directions of the axes of the ellipsoidal figure assumed by a molecule originally spherical ”

“ Relations between the Strains and the Stresses.—When the strains are known, the stresses can be found from a generalized Hooke's law, which can be deduced from the principle of energy, combined with consideration of symmetry. If the solid is isotropic, i.e. is symmetrical in its elastic properties in all directions round a point, the relations between stress and strain are of the form
the values of the other four components of strain can be written down from symmetry. ”

“ A body which has been strained beyond the limit of linear elasticity is often said to have suffered an “over-strain.” When the load is removed, the set which can be observed is not entirely permanent; but it gradually diminishes with lapse of time. This phenomenon is named “elastic after-working.” If, on the other hand, the load is maintained constant, the strain is gradually increased. This effect indicates a gradual flowing of solid bodies under great stress ”