A Book of Exposition Part 2

[Ill.u.s.tration: Fig. 7.]

As the matrices approach the line, their upper ends are carried over a spring _g3_, projecting through the a.s.sembler face-plate from the rear, as shown in Fig. 7, its purpose being to hold the matrices forward and prevent them from falling back in such a manner that succeeding matrices and s.p.a.ces or justifiers will pa.s.s improperly ahead of them.

The descending matrices also pa.s.s beneath a long depending spring _g4_, which should be so adjusted as barely to permit the pa.s.sage of the thickest matrix.

[Ill.u.s.tration: Fig. 8.]

[Ill.u.s.tration: Fig. 9.]

After the composition of the line is completed in the a.s.sembling elevator _G_, as shown in Fig. 8, the elevator is raised as shown in Fig. 9, so as to present the line between the depending fingers of the transfer-carriage _N_, which then moves to the left to the position shown by dotted lines in Fig. 9, thereby bringing the line into the first elevator _O_, which then descends, carrying the line of matrices downwards, as shown in Fig. 10, to its position in front of the mold and between the confining jaws _P_, _P_, mounted in the main frame, which determine the length of the line.

Figs. 11 and 12 show the casting mechanism in vertical section from front to rear. When the first elevator _O_ lowers the line, as just described, the mold and the pot _M_ stand in their rearward positions, as shown in Fig. 11.

[Ill.u.s.tration: Fig. 10.]

[Ill.u.s.tration: Fig. 11.]

The mold-carrying wheel is sustained by a horizontal slide, and as soon as the matrix line is lowered to the casting position, a cam at the rear pushes the slide and mold wheel forward until the front face of the mold is closed tightly against the rear face of the matrix line, as shown in Fig. 12.

[Ill.u.s.tration: Fig. 12.]

While this is taking place, the pot, having its supporting legs mounted on a horizontal shaft, swings forward until its mouth is closed tightly against the back of the mold, as shown in Fig. 12. While the parts are in this position, the justifying bar _Q_ is driven up and pushes the s.p.a.ces or justifiers upward through the line of matrices until the line is expanded or elongated to fill completely the gap between jaws _P_, _P_.

In order to secure exact alignment of the matrices vertically and horizontally, the bar _Q_ acts repeatedly on the s.p.a.ces, and the line is slightly unlocked endwise and relocked. This is done that the matrices may be temporarily released to facilitate the accurate adjustment demanded. While the justified line is locked fast between the jaws, the elevator, and the mold, the plunger _m2_ in the pot descends and drives the molten metal before it through the spout or mouth of the pot into the mold, which is filled under pressure, so that a solid slug is produced against the matrices. The pot then retreats, and its mouth breaks away from the back of the slug in the mold, while, at the same time, the mold retreats to draw the type-characters on the contained slug out of the matrices. The mold wheel now revolves, carrying the rear edge of the slug past a stationary tr.i.m.m.i.n.g-knife, not shown, and around to the position in front of the ejector, as previously described and shown in Fig. 4, whereupon the ejector advances and drives the slug between two side tr.i.m.m.i.n.g-knives into the galley at the front.

DISTRIBUTION

After the casting action the first elevator _O_ rises and carries the matrix line above the original or composing level, as shown in Fig. 13.

The line is then drawn horizontally to the right until the teeth of the matrices engage the toothed elevator bar _R_, which swings upward with the matrices, thus separating the matrices from the s.p.a.ces or justifiers _I_, which remain suspended in the frame, so that they may be pushed to the right, as indicated by the arrow, into their magazine.

[Ill.u.s.tration: Fig. 13.]

[Ill.u.s.tration: Fig. 14.]

When the line of matrices is raised to the distributor, it is necessary that the matrices shall be separated and presented one at a time to the distributor bar, between the threads of the horizontal carrier-screws.

This is accomplished as shown in Figs. 14 and 15. A horizontal pusher or line-shifter _S_ carries the line of matrices forward from the elevator bar _R_ into the so-called distributor box, containing at its opposite sides two rails _u_, having near their forward ends shoulders _u2_, against which the forward matrix abuts so as to prevent further advance of the line, which is urged constantly forward by the follower or line-shifter _S_. A vertically reciprocating lifting finger _V_ has its upper end shouldered to engage beneath the foremost matrix, so as to push it upward until its upper ears are lifted above the detaining shoulder _u2_, so that they may ride forward on the upwardly inclined inner ends of the rails, as shown in Fig. 14. The matrices thus lifted are engaged by the screws and carried forward, and, as they move forward, they are gradually raised by the rails until the teeth finally engage themselves on the distributor bar _T_, from which they are suspended as they are carried forward, over the mouth of the magazine, until they fall into their respective channels, as shown in Fig. 15.

The distributor box also contains on opposite sides shorter rails, _u4_, adapted to engage the lower ends of the matrices, to hold them in position as they are lifted. The lifting finger _V_ is mounted on a horizontal pivot in one end of an elbow lever mounted on pivot _v2_ and actuated by a cam on the end of one of the carrier-screws, as shown in Figs. 2 and 15.

Tr.i.m.m.i.n.g-KNIVES

In practice there is occasionally found a slight irregularity in the thickness of slugs, and thin fins are sometimes cast around the forward edges. For the purpose of reducing them to a uniform thickness, they are driven on their way to the galley between two vertical knives, as shown in Figs. 4 and 16. The inner knife is stationary, but the outer knife is adjustable in order that it may accommodate slugs of different thicknesses. This adjustment is made by the knife being seated at its outer edge against a supporting bar or wedge, having at opposite ends two inclined surfaces seated against supporting screws in the knife-block. A lever engages a pin on the wedge for the purpose of moving it endwise; when moving in one direction, it forces the knife inward toward the stationary knife, and when moved in the other direction, it forces it to retreat under the influence of a spring seated in the block. The wedge is provided with a series of teeth engaged by a spring-actuated pin or dog, whereby the wedge and the knife are stopped in proper positions to insure the exact s.p.a.ce required between the two knives.

[Ill.u.s.tration: Fig. 15.]

The back knife, secured to the frame for tr.i.m.m.i.n.g the base of the slug as it is carried past by the revolving wheel, should be kept moderately sharp and adjusted so as to fit closely against the back of the pa.s.sing mold. Particular attention should be paid to this feature. The edge of the knife must bear uniformly across the face of the mold.

[Ill.u.s.tration: Fig. 16.]

The front knives, between which the slug is ejected, should not be made too sharp. After being sharpened, the thin edge can be advantageously removed by the use of a thin oilstone applied against the side face; that is, against the face past which the slug is carried.

The stationary or left-hand knife should be so adjusted as to align exactly with the inner side of the mold. Under proper conditions this knife does not trim the side face of the slug, but acts only to remove any slight fins or projections at the front edge.

The right-hand knife, adjustable by means of a wedge and lever, should stand exactly parallel with the stationary knife. It trims the side of the slug on which the ribs are formed, and it serves to bring the slug to the exact thickness required.

FOOTNOTES:

[Footnote 2: From Theodore L. De Vinne's _Modern Methods of Book Composition_, pp. 403-425. The Century Company, New York, 1904.]

THE EXPOSITION OF A PROCESS IN NATURE

THE PEA WEEVIL[3]

_Jean Henri Fabre_

Peas are held in high esteem by mankind. From remote ages man has endeavored, by careful culture, to produce larger, tenderer, and sweeter varieties. Of an adaptable character, under careful treatment the plant has evolved in a docile fashion, and has ended by giving us what the ambition of the gardener desired. To-day we have gone far beyond the yield of the Varrons and Columelles, and further still beyond the original pea; from the wild seeds confided to the soil by the first man who thought to scratch up the surface of the earth, perhaps with the half-jaw of a cave-bear, whose powerful canine tooth would serve him as a ploughshare!

Where is it, this original pea, in the world of spontaneous vegetation?

Our own country has nothing resembling it. Is it to be found elsewhere?

On this point botany is silent, or replies only with vague probabilities.

We find the same ignorance elsewhere on the subject of the majority of our alimentary vegetables. Whence comes wheat, the blessed grain which gives us bread? No one knows. You will not find it here, except in the care of man; nor will you find it abroad. In the East, the birthplace of agriculture, no botanist has ever encountered the sacred ear growing of itself on unbroken soil.

Barley, oats, and rye, the turnip and the beet, the beetroot, the carrot, the pumpkin, and so many other vegetable products, leave us in the same perplexity; their point of departure is unknown to us, or at most suspected behind the impenetrable cloud of the centuries. Nature delivered them to us in the full vigor of the thing untamed, when their value as food was indifferent, as to-day she offers us the sloe, the bullace, the blackberry, the crab; she gave them to us in the state of imperfect sketches, for us to fill out and complete; it was for our skill and our labor patiently to induce the nourishing pulp which was the earliest form of capital, whose interest is always increasing in the primordial bank of the tiller of the soil.

As storehouses of food the cereal and the vegetable are, for the greater part, the work of man. The fundamental species, a poor resource in their original state, we borrowed as they were from the natural treasury of the vegetable world; the perfected race, rich in alimentary materials, is the result of our art.

If wheat, peas, and all the rest are indispensable to us, our care, by a just return, is absolutely necessary to them. Such as our needs have made them, incapable of resistance in the bitter struggle for survival, these vegetables, left to themselves without culture, would rapidly disappear, despite the numerical abundance of their seeds, as the foolish sheep would disappear were there no more sheep-folds.

They are our work, but not always our exclusive property. Wherever food is ama.s.sed, the consumers collect from the four corners of the sky; they invite themselves to the feast of abundance, and the richer the food the greater their numbers. Man, who alone is capable of inducing agrarian abundance, is by that very fact the giver of an immense banquet at which legions of feasters take their place. By creating more juicy and more generous fruits, he calls to his enclosures, despite himself, thousands and thousands of hungry creatures, against whose appet.i.tes his prohibitions are helpless. The more he produces, the larger is the tribute demanded of him. Wholesale agriculture and vegetable abundance favor our rival, the insect.

This is the immanent law. Nature, with an equal zeal, offers her mighty breast to all her nurslings alike; to those who live by the goods of others no less than to the producers. For us, who plough, sow, and reap, and weary ourselves with labor, she ripens the wheat; she ripens it also for the little Calender-beetle, which, although exempted from the labor of the fields, enters our granaries none the less, and there, with its pointed beak, nibbles our wheat, grain by grain, to the husk.

For us, who dig, weed, and water, bent with fatigue and burned by the sun, she swells the pods of the pea; she swells them also for the weevil, which does no gardener's work, yet takes its share of the harvest at its own hour, when the earth is joyful with the new life of spring.

Let us follow the manoeuvres of this insect which takes its t.i.the of the green pea. I, a benevolent rate-payer, will allow it to take its dues; it is precisely to benefit it that I have sown a few rows of the beloved plant in a corner of my garden. Without other invitation on my part than this modest expenditure of seed-peas, it arrives punctually during the month of May. It has learned that this stony soil, rebellious at the culture of the kitchen-gardener, is bearing peas for the first time. In all haste therefore it has hurried, an agent of the entomological revenue system, to demand its dues.

Whence does it come? It is impossible to say precisely. It has come from some shelter, somewhere, in which it has pa.s.sed the winter in a state of torpor. The plane-tree, which sheds its rind during the heats of the summer, furnishes an excellent refuge for homeless insects under its partly detached sheets of bark.

I have often found our weevil in such a winter refuge. Sheltered under the dead covering of the plane, or otherwise protected while the winter lasts, it awakens from its torpor at the first touch of a kindly sun.

The almanac of the instincts has aroused it; it knows as well as the gardener when the pea-vines are in flower, and seeks its favorite plant, journeying thither from every side, running with quick, short steps, or nimbly flying.

A small head, a fine snout, a costume of ashen grey sprinkled with brown, flattened wing-covers, a dumpy, compact body, with two large black dots on the rear segment--such is the summary portrait of my visitor. The middle of May approaches, and with it the van of the invasion.