Category: 19th Century

 

Yeah I don’t know what any of this means:

MANIÈRE D’OPÉRER.

Première préparation de la plaque.

Nota.—Pour être plus court dans la description qui va suivre, j’indiquerai chaque substance en abrégé. Ainsi je dirai, pour désigner la solution aqueuse de bichlorure de mercure, sublimé; pour la solution de cyanure de mercure, cyanure; pour l’huile de pétrole acidulée, huile; pour la dissolution de chlorure d’or et de platine, or et platine; et pour l’oxyde de fer, rouge seulement.

On polit la plaque avec du sublimé et du tripoli d’abord, et ensuite avec du rouge[7], jusqu’à ce qu’on arrive à un beau noir. Puis, on pose la plaque sur le plan horizontal et on y verse la solution de cyanure que l’on chauffe avec la lampe, absolument comme si l’on fixait une épreuve au chlorure d’or. Le mercure se dépose et forme une couche blanchâtre. On laisse un peu refroidir la plaque, et après avoir renversé le liquide, on la sèche en la frottant avec du coton et en la saupoudrant de rouge.

Il s’agit maintenant de polir la couche blanchâtre déposée par le mercure. Avec un tampon de coton imbibé d’huile et de rouge, on frotte cette couche juste assez pour qu’elle devienne d’un beau noir. Ou pourra, en dernier lieu, frotter assez fortement, mais avec du coton seul, pour amincir le plus possible la couche acidulée.

Ensuite on place la plaque sur le plan horizontal et on y verse la dissolution d’or et de platine. On chauffe comme à l’ordinaire; on laisse refroidir et puis on renverse le liquide que l’on sèche, en frottant légèrement avec du coton et du rouge.

Il faut faire cette opération avec soin, surtout lorsqu’on ne doit pas continuer immédiatement l’épreuve; car autrement, on laisserait sur la plaque des lignes de liquide, qu’il est toujours difficile de faire disparaître. Par ce dernier frottage la plaque ne doit être que séchée et non pas polie.

Ici se borne la première préparation de la plaque, celle qui peut être faite longtemps à l’avance.

Seconde préparation.

Nota. Je ne crois pas convenable de mettre entre cette opération et l’iodage de la plaque un intervalle de plus de douze heures.

Nous avons laissé la plaque avec un dépôt d’or et de platine. Pour polir cette couche métallique, il faut prendre avec un tampon de coton de l’huile et du rouge, et frotter jusqu’à ce que la plaque redevienne noire; et puis avec de l’alcool et du coton seulement, on enlève le plus possible cette couche d’huile et de rouge.

Alors on frotte assez fortement, et en repassant plusieurs fois aux mêmes endroits, la plaque avec du coton imprégné de cyanure. Comme cette couche sèche très-promptement, elle pourrait laisser sur la plaque des traces d’inégalité; pour éviter cela, il faut repasser le cyanure, et pendant que la plaque est encore humide, avec un tampon imbibé d’un peu d’huile on s’empresse de frotter sur toute la surface de la plaque, et de mêler ainsi ces deux substances; puis, avec un tampon de coton sec, on frotte pour unir et en même temps pour dessécher la plaque, en ayant soin d’enlever du tampon de coton les parties qui s’humectent de cyanure et d’huile. Enfin, comme le coton laisse encore des traces, on saupoudre également la plaque d’un peu de rouge que l’on fait tomber en frottant légèrement et en rond.

Ensuite, avec un tampon imprégné d’huile seulement, on frotte la plaque également, et de manière à faire revenir le bruni du métal; et puis on saupoudre avec du rouge, et l’on frotte très-légèrement en rond, de manière à faire tomber tout le rouge qui entraîne avec lui la surabondance de la couche acidulée[8].

Enfin, avec un tampon de coton un peu ferme, on frotte fortement pour donner le dernier poli[9].

Il n’est pas nécessaire de renouveler souvent les tampons imbibés d’huile et de rouge; il faut seulement les garantir de la poussière.

J’ai dit plus haut que la première préparation de la plaque peut servir indéfiniment; mais on comprend que la seconde doit être modifiée selon qu’on opère sur une plaque qui a reçu une épreuve fixée ou une non fixée.

Sur l’épreuve fixée.

Il faut enlever les taches laissées par l’eau du lavage, avec l’oxyde rouge et de l’eau faiblement acidulée d’acide nitrique (à 2 degrés dans cette saison, et moins dans l’été).

Ensuite, il faut polir la plaque avec de l’huile et du rouge pour enlever toutes les traces de l’image qu’on efface.

On continue alors l’opération comme je viens de le dire plus haut pour la seconde préparation de la plaque neuve et à partir de l’emploi de l’alcool.

Sur l’épreuve non fixée (mais dont la couche sensible a été enlevée comme à l’ordinaire, dans l’hyposulfite de soude).

D’abord, il faut frotter la plaque avec de l’alcool et du rouge pour enlever les traces de l’huile qui a servi à faire l’épreuve précédente.

On continue ensuite comme il est indiqué plus haut pour la plaque neuve, et à partir de l’emploi de l’alcool.

Here we have the death-defying story of the laying of the Trans-Atlantic telegraph cable! Quite a monument for the technological achievement. Excerpt below:

The landing of the cable took place on Wednesday, the fifth of August, near the hour of sunset. As it was too late to proceed that evening, the ships remained at anchor till the morning. They got under weigh at an early hour, but were soon checked by an accident [Pg 132]which detained them another day. Before they had gone five miles, the heavy shore end of the cable caught in the machinery and parted. The Niagara put back, and the cable was “underrun” the whole distance. At length the end was lifted out of the water and spliced to the gigantic coil, and as it dropped safely to the bottom of the sea, the mighty ship began to stir. At first she moved very slowly, not more than two miles an hour, to avoid the danger of accident; but the feeling that they were at last away was itself a relief. The ships were all in sight, and so near that they could hear each other’s bells. The Niagara, as if knowing that she was bound for the land out of whose forests she came, bowed her head to the waves, as her prow was turned toward her native shores.

Slowly passed the hours of that day. But all went well, and the ships were moving out into the broad Atlantic. At length the sun went down in the west, and stars came out on the face of the deep. But no man slept. A thousand eyes were watching a great experiment as those who have a personal interest in the issue. All through that night, and through the anxious days and nights that followed, there was a feeling in every soul on board, as if some dear friend were at the turning-point of life or death, and they were watching beside him. There was a strange, unnatural silence in the ship. Men paced the deck with soft and muffled tread, speaking only in whispers, [Pg 133]as if a loud voice or a heavy footfall might snap the vital cord. So much had they grown to feel for the enterprise, that the cable seemed to them like a human creature, on whose fate they hung, as if it were to decide their own destiny.

There are some who will never forget that first night at sea. Perhaps the reaction from the excitement on shore made the impression the deeper. There are moments in life when every thing comes back upon us. What memories came up in those long night hours! How many on board that ship, as they stood on the deck and watched that mysterious cord disappearing in the darkness, thought of homes beyond the sea, of absent ones, of the distant and the dead!

But no musings turn them from the work in hand. There are vigilant eyes on deck. Mr. Bright, the engineer of the Company, is there, and Mr. Everett, Mr. De Sauty, the electrician, and Professor Morse. The paying-out machinery does its work, and though it makes a constant rumble in the ship, that dull, heavy sound is music to their ears, as it tells them that all is well. If one should drop to sleep, and wake up at night, he has only to hear the sound of “the old coffee-mill,” and his fears are relieved, and he goes to sleep again.

Saturday was a day of beautiful weather. The ships were getting farther away from land, and began to steam ahead at the rate of four and five miles an [Pg 134]hour. The cable was paid out at a speed a little faster than that of the ship, to allow for any inequalities of surface on the bottom of the sea. While it was thus going overboard, communication was kept up constantly with the land. Every moment the current was passing between ship and shore. The communication was as perfect as between Liverpool and London, or Boston and New York. Not only did the electricians telegraph back to Valentia the progress they were making, but the officers on board sent messages to their friends in America, to go out by the steamers from Liverpool. The heavens seemed to smile on them that day. The coils came up from below the deck without a kink, and unwinding themselves easily, passed over the stern into the sea. Once or twice an alarm was created by the cable being thrown off the wheels. This was owing to the sheaves not being wide enough and deep enough, and being filled with tar, which hardened in the air. This was a great defect of the machinery which was remedied in the later expeditions. Still it worked well, and so long as those terrible brakes kept off their iron gripe, it might work through to the end.

All day Sunday the same favoring fortune continued; and when the officers, who could be spared from the deck, met in the cabin, and Captain Hudson read the service, it was with subdued voices and grateful hearts they responded to the prayers to Him who [Pg 135]spreadeth out the heavens, and ruleth the raging of the sea.

On Monday they were over two hundred miles at sea. They had got far beyond the shallow waters off the coast. They had passed over the submarine mountain which figures on the charts of Dayman and Berryman, and where Mr. Bright’s log gives a descent from five hundred and fifty to seventeen hundred and fifty fathoms within eight miles! Then they came to the deeper waters of the Atlantic, where the cable sank to the awful depth of two thousand fathoms. Still the iron cord buried itself in the waves, and every instant the flash of light in the darkened telegraph room told of the passage of the electric current.

But Monday evening, about nine o’clock, occurred a mysterious interruption, which staggered all on board. Suddenly the electrical continuity was lost. The cable was not broken, but it ceased to work. Here was a mystery. De Sauty tried it, and Professor Morse tried it. But neither could make it work. It seemed that all was over. The electricians gave it up, and the engineers were preparing to cut the cable, and to endeavor to wind it in, when suddenly the electricity came back again. This made the mystery greater than ever. It had been interrupted for two hours and a half. This was a phenomenon which has never been explained. Professor Morse was of opinion that the cable, in getting off the wheels, had been strained so [Pg 136]as to open the gutta-percha, and thus destroy the insulation. If this be the true explanation, it would seem that on reaching the bottom the seam had closed, and thus the continuity had been restored. But it was certainly an untoward incident, which “cast ominous conjecture on the whole success,” as it seemed to indicate that there were at the bottom of the sea causes which were wholly unknown and against which it was impossible to provide.

The return of the current was like life from the dead. Says Mullaly:

“The glad news was soon circulated throughout the ship, and all felt as if they had a new life. A rough, weather-beaten old sailor, who had assisted in coiling many a long mile of it on board the Niagara, and who was among the first to run to the telegraph office to have the news confirmed, said he would have given fifty dollars out of his pay to have saved that cable. ‘I have watched nearly every mile of it,’ he added, ‘as it came over the side, and I would have given fifty dollars, poor as I am, to have saved it, although I don’t expect to make any thing by it when it is laid down.’ In his own simple way he expressed the feelings of every one on board, for all are as much interested in the success of the enterprise as the largest shareholder in the Company. They talked of the cable as they would of a pet child, and never was child treated with deeper solicitude than that with which the cable is watched by them. You could see the tears standing in the eyes of some as they almost cried for joy, and told their messmates that it was all right.”

This classic by Gillette and Hill introduces readers to modern-day (back in the 1800s – haha!) concrete construction. Check out this excerpt:

The derrick buckets by which the concrete was hoisted and handled to the work were of special construction. A bucket was desired which would serve several distinct purposes. It must first be able to hold a full mixer batch of material, since, with the derrick arrangement, economy in hoisting necessitated hoisting in large units and also because storage capacity was required of the bucket for wheelbarrow work. The four derricks did not command the entire area of a floor; there were corners and other irregular areas outside of the circles covered by the several booms over which the concrete must be distributed[Pg 486] by barrows or carts. A bucket large enough to supply the barrows, while a second bucket was being lowered, charged from the mixer and hoisted, was required. In the second place, a bucket was required whose contents could be discharged all at once or in smaller portion at will. Finally a bucket was desired which could be made to distribute its load along a narrow girder form or in a thin sheet for a floor slab.

To meet these requirements the bucket shown in Fig. 222 was designed. It held 42 cu. ft., or about 1.55 cu. yds. of concrete. It had a hopper bottom terminating in a short rectangular discharge spout closed by a lever operated under cut gate, which could be opened as much or as little as desired. To the underside of the bucket there was attached a four-leg frame in which the bucket stood when not suspended. Ordinarily, that is within the circles commanded by the derricks, the buckets were discharged suspended and directly into the forms, the character of the discharge gate permitting a thin sheet to be spread for floor slabs or a narrow girder or wall form to be filled without spilling or shock. For wheelbarrow work outside the reach of the derricks the mode of procedure was as follows: A timber platform about 3 ft. high and having room for standing two buckets was set just on the edge of the circle commanded by the derrick boom. Two buckets were used. A full bucket was hoisted and set on the platform, with its spout overhanging. This bucket served as a storage bin for feeding the wheelbarrows while the second bucket was being lowered, charged and hoisted to take its place on the platform, and serve in turn as a storage hopper.

PLACING AND RAMMING.—A wet concrete is usually used in building work except on occasions, for exterior wall work and except for pitch roof work, where a wet mixture would run down the slope. Placing and tamping are therefore, essentially pouring and puddling operations. The pouring should be done directly from the barrows, carts, or buckets if possible; dumping onto shoveling boards and shoveling makes an extra operation and increases the cost by the wages of the shoveling gang. Where shoveling boards are necessary, take care that they are placed close to the forms being filled, as it is wasteful of time to carry concrete in shovels, even for[Pg 487] a half dozen paces. Before pouring any concrete, the inside of the forms should be wet down thoroughly with a hose or sprinkler, if a hose stream is not available. The final inspection of forms and reinforcement just before concreting will have made certain that they are ready for the concrete, so far as line and level of forms and presence and proper arrangement of the reinforcement are concerned, but the concrete foreman must watch that no displacement occurs in pouring and puddling, and must make certain particularly that the forms are clean.

In pouring columns it is essential that the operation be continuous to the bottom of the beam or girder. It is also advisable to pour columns several hours ahead of the girders. Puddling should be thorough, as its purpose is to work the concrete closely around the reinforcement and into the angles of the mold and to work out air bubbles. A tool resembling a broad chisel is one of the best devices for puddling or slicing. In slab and girder construction, the pouring should be continuous from bottom of girder to top of slab. Work should never be stopped-off at horizontal planes. As in columns, careful puddling is essential in pouring beams. In slab work, the concrete is best compacted by tamping or rolling. A broad faced rammer should be used for tamping wet concrete, or a wooden roller covered with sheet steel, weighing about 250 lbs., and having a 30-in. face.

Theoretically, concreting should be a continuous operation, but practically it cannot be made so. Bonding fresh concrete to concrete that has hardened, though it has been done with great perfection by certain methods as described in Chapter XXIV, must still be held as uncertain. Ordinarily, at least, a plane of weakness exists where the junction is made and in stopping off work it should be done where these planes of weakness will cause the least harm. Experts are by no means agreed on the best location of these planes, but the following is recognized good practice. Work once started, pouring a column, should not be stopped until the column is completed to the bottom of the girder. For beams and girders; stop concrete at center of girder with a vertical face at right angles to the girder, or directly over the center of the columns; in beams connecting with girders, stop concrete at center of[Pg 488] span, or directly over center of connecting girder; stop always with a vertical face and never with a sloping face, and never with a girder partly filled. For slabs; stop concrete at center of span, or directly over middle of supporting girder or beam; stop always with vertical joints. If for any cause work must be stopped at other points, than those stated, the fresh concrete and the hardened concrete must be bonded by one of the methods described in Chapter XXIV.

CONSTRUCTING WALL COLUMNS FOR A BRICK BUILDING.—The columns, 12 in number, were constructed to strengthen the brick walls of a power station and were built as shown by Figs. 223 and 224, one at a time. The staging, 50 ft. high and 4×6 ft. in plan, was erected against the wall which had been shored, a portion of the wall was cut out and forms erected and the concrete column substituted for the section of wall which was removed. The staging was then moved into position for another column.

Wow. How interesting! The amount of technical knowledge present in this 19th Century book!