Chapter 2

All these devices, however, are not of permanent utility; they are only temporarily required (i.e., up to the time that the beton has become hard and formed a permanent traverse tie between the two faces of the wall), for it is manifest that the ultimate object of all slab concrete construction is: (a) To retain and to mould the plastic concrete used in forming the wall; (b) to key or fix the slabs to the mass which they themselves have moulded; and (c) to form a facing to the wall. When these objects shall have been accomplished, there is no further need of any tie whatever beyond that which naturally obtains in a concrete wall. In West's system, however, where the slabs are keyed course to course, any kind of transverse tie to be used during the process of construction, except that used in the starting course, is entirely dispensed with, and the courses of slabs above depend solely upon the courses of slabs below them for their stability and rigidity up to the time that the plastic filling-in has been deposited and become hard between both faces of the wall.

There is, however, a more decided difference between West's system and those previously in use, for it is marked by the fact that the slabs composing the shell of the whole structure in many cases may be built up before the filling-in is deposited between the slabs, and in none of the other cases can this be done. In fact, only in the first two cases before mentioned can more than one course of slabs be laid before filling-in of some kind must be done. Compared with the ordinary method of building in concrete, this system avoids: 1. The charge for use and waste of wood casings; 2. finishing the face of the work (both inside and outside) after the structure is raised, and, therefore, the bursting-off of the finished face; and 3. the difficulties encountered in working mouldings and other ornaments on the face of the work by the ordinary plasterer's methods. It also provides a face of any of the usual colors that may be obtained in concrete, besides a facing of any other material, such as marble, etc., and produces better and more durable work, at the same time showing a saving in cost, especially in the better classes of work; all of which is effected with less plant than ordinarily required. For engineering work, such as sea walls, the hexagonal slabs, made of greater thickness than those employed for ordinary walling, will answer admirably, especially if the grooves be made proportionately larger. By the use of these slabs the work may be built up with great rapidity. For small domestic work, such as the dwellings of artisans, these slabs; which are of such a form as to render them easy of transport, may be supplied to the workmen themselves in order that they may erect their own dwellings, as, on account of the simplicity of this system and the absence of need of plant, any intelligent mechanic can do the work.

Any arrangement of independent scaffolding may be employed for this system, but that invented specially for the purpose by Mr. Frank West, as shown in Fig. 26 of our engravings, is to be preferred. It not only supplies the necessary scaffold, but also the necessary arrangements for hoisting the slabs, as well as for raising the liquid concrete and depositing it behind the slabs. It is really an independent scaffold, and may be used wherever a light tramway of contractor's rails can be laid, which in crowded thoroughfares would of necessity be upon a staging erected over the footway. The under frame is carried upon two bogie frames running upon the contractor's rail, by which means it is enabled to turn sharp curves, a guide plate inside the inner rail being provided at the curves for this purpose. The scaffold itself consists of a climbing platform made to travel up or down by means of four posts which have racks attached to their faces, and which are fixed to the under frame and securely braced to resist racking strains. A worm gearing, actuated by a wheel on the upper side of the scaffold, causes the scaffold to ascend or descend. A railgrip, made to act at the curves as well as on the straight portions of the rail by being attached to a radial arm fixed to the under frame, assists the stability of the scaffold where required, but the gauge of the rails is altered to render the scaffold more or less stable according to its height. Combined with the same machine, and traveling up and down one of the same posts used for the scaffold, is an improved crane. Its action depends upon the proposition in geometry that if the length of the base of a triangle be altered, its angles, and therefore its altitude, are altered. A portion of the vertical post up and down which the crane climbs forms the base of a triangle, and a portion of the jib, together with the stay, forms the remaining two sides. Hence, by causing the foot of one or the other to travel upward, by means of the worm gearing, the upper end of the jib is either elevated or depressed.

The concrete elevator, which is also combined with the scaffold, consists of a series of buckets carried upon two parallel endless chains passing over two pairs of wheels. On the under frame is fixed a hopper, into which is thrown, either by hand or from a concrete mixer running upon the rails, the material to be hoisted, and from which it gravitates into a narrow channel, through which pass the buckets (attached to the chain) with a shovel-like action. The buckets, a motor being applied to one pair of wheels, thus automatically fill themselves, and on arriving at top are made to tip their contents, and jar themselves, automatically into a hopper by means of a small pinion, keyed to the shaft by which they are attached to the endless chain, becoming engaged in a small rack fixed for that purpose. From the upper hopper the material is taken away to the required destination by means of a worm working in a tube. For varying heights, extra lengths of chain and buckets are inserted and secured by a bolt passed through each end link, and secured by a nut. By using this scaffold, a saving in plant, cartage, and labor is effected. The elevator may also be used for raising any other material besides concrete.

Such is the new system of concrete construction and scaffolding of Messrs. West, which appears to be based on sound and reasonable principles, and to have been thoughtfully and carefully worked out, and which moreover gives promise of success in the future. We may add in conclusion that specimens of the work and a model of a scaffold are shown by Messrs. West at their stand in the Inventions Exhibition.--_Iron_.

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THE BLUE PRINT PROCESS.

R.W. JONES.

1. Cover a flat board, the size of the drawing to be copied, with two or three thicknesses of common blanket or its equivalent.

2. Upon this place the prepared paper, sensitive side uppermost.

3. Press the tracing firmly and smoothly upon this paper, by means of a plate of clear glass, laid over both and clamped to the board.

4. Expose the whole--in a clear sunlight--from 4 to 6 minutes. In a winter's sun, from 6 to 10 minutes. In a clear sky, from 20 to 30 minutes.

5. Remove the prepared paper and pour clear water on it for one or two minutes, saturating it thoroughly, and hang up to dry.

The sensitive paper may be readily prepared, the only requisite quality in the _paper_ itself being its ability to stand washing.

Cover the surface evenly with the following solution, using such a brush as is generally employed for the letter-press: 1 part soluble citrate of iron (or citrate of iron and ammonia), 1 part red prussiate of potash, and dissolve in 10 parts of water.

The solution must be kept carefully protected from light, and better results are obtained by not mixing the ingredients until immediately required. After being coated with the solution, the paper must be laid away to dry in a dark place, and must be shielded entirely from light until used. When dry, the paper is of a yellow and bronze color. After exposure the surface becomes darker, with the lines of the tracing still darker. Upon washing, the characteristic blue tint appears, with the lines of the tracing in vivid contrast. Excellent results have been obtained from glass negatives by this process.--_Proc. Eng. Club, Phila._

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REPRODUCTION OF DRAWINGS IN BLUE LINES ON WHITE GROUND.

A.H. HAIG.

The following process for making photographic copies of drawings in blue lines on white background was invented by H. Pellet, and is based on the property of perchloride of iron of being converted into protochloride on exposure to light. Prussiate of potash when brought into contact with the perchloride of iron immediately turns the latter blue, but it does not affect the protochloride.

A bath is first prepared consisting of ten parts perchloride of iron, five parts oxalic or some other vegetable acid, and one hundred parts water. Should the paper to be used not be sufficiently sized, dextrine, gelatine, isinglass, or some similar substance must be added to the solution. The paper is sensitized by dipping in this solution and then dried in the dark, and may be kept for some length of time. To take a copy of a drawing made on cloth or transparent paper, it is laid on a sheet of the sensitive paper, and exposed to light in a printing frame or under a sheet of glass. The length of exposure varies with the state of the weather from 15 to 30 seconds in summer to from 40 to 70 seconds in winter, in full sunlight. In the shade, in clear weather, 2 to 6 minutes, and in cloudy weather, 15 to 40 minutes may be necessary. The printing may also be done by electric light. The print is now immersed in a bath consisting of 15 to 18 parts of prussiate of potash per 100 parts of water. Those parts protected from the light by the lines of the drawing immediately turn blue, while the rest of the paper, where the coating has been converted into protochloride by the effects of light, will remain white. Next, the image is freely washed in water, and then passed through a bath consisting of 8 to 10 parts of hydrochloric acid to 100 parts of water, for the purpose of removing protoxide of iron salt.

It is now again washed well in clean water and finally dried, when the drawing will appear in blue on a white background.--_Proc. Eng. Club, Phila._

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[PROCEEDINGS OF THE ENGINEERS' CLUB OF PHILADELPHIA.]

RELATIVE COSTS OF FLUID AND SOLID FUELS.

[Footnote: Read June 20, 1885.]

By JAMES BEATTY, JR., Member of the Club.

During the past twenty-five years there have been numerous efforts to introduce fluid fuels as substitutes for coal, for the evaporation of water in boilers, metallurgical operations, and, on a small scale, for domestic purposes.

The advantages claimed for these fuels are: Reduction in the number of stokers, one man being able to do the work of four using solid fuel. Reduction in weight, amounting to one-half with the better classes. Reduction in bulk; for petroleum amounting to about thirty-six per cent., and with the gases, depending on the amount of compression. Ease of kindling and extinguishing fires, and of regulation of temperature. Almost perfect combustion and cleanliness.

Siemens used gas, distilled from coal and burnt in his well known regenerative furnace.

Deville experimented with petroleum on two locomotives running on the Paris and Strassburg Railroad.

Selwyn experimented with creosote in a small steam yacht, and under the boilers of steamship Oberlin.

Holland experimented with water-gas in the furnace of a locomotive running on the Long Island Railroad.

Isherwood experimented with petroleum under the boilers of United States steamers.

Three railroads in Russia are using naphtha in their locomotives, and steamers on the Volga are using the same fuel.

Wurtz experimented with crude petroleum in a reheating furnace at Jersey City.

Dowson, Strong, Lowe, and others have devised systems for the production of water gas.

These experiments, in general, have produced excellent results when considered merely in the light of heat production, but, in advocating their systems, the inventors seem to have overlooked the all-important item of cost.

It is the object of this paper to show the impracticability of such systems when considered from a commercial standpoint, so long as the supply of coal lasts, and prices keep within reasonable limits.

In many cases, authors on the subject have given purely theoretical results, without allowing for losses in the furnace.

The fuels to be considered are anthracite and bituminous coals, crude petroleum, and coal, generator and water gases.

The average compositions of these fuels (considering only the heating agents), as deduced from the analysis of eminent chemists, are:

PERCENTAGE BY WEIGHT.

________________________________________________________ | C | H | O | CO |CH_{4}|C_{2}H_{4} +----+-----+---+----+------+---------- Anthracite |87.7| 3.3 |3.2| | | Bituminous |80.8| 5.0 |8.2| | | Petroleum |84.8|13.1 |1.5| | | Coal gas | | 6.5 | |14.3| 52.4 | 14.8 Generator gas | | 1.98| |35.5| 1.46| Water gas | | 6.3 |0.6|87.8| 1.2 | ------------------+----+-----+---+----+------+----------

We will employ the formula of Dulong--

h = 14,500 C + 62,000 (H - O/8)

to compute the theoretical heating powers of these fuels. In the case of methane, CH_{4}, the formula is not true, but the error is not great enough to seriously affect the result. This gives for the combustion of one pound of:

Anthracite 14,500 Br. Heat Units. Bituminous 14,200 " " " Petroleum 20,300 " " " Coal gas 20,200 " " " Generator gas 3,100 " " " Water gas 8,500 " " "

Reducing the above to terms of pounds of water evaporated from 212° F., we have:

POUNDS OF WATER EVAPORATED FROM 212° F.

Anthracite 15.023 Bituminous 14.69 Petroleum 21.00 Coal gas 20.87 Generator gas 3.21 Water gas 8.7

The results of experiments show the efficiency of fluid-burning furnaces to be about ninety per cent., while with coal sixty per cent. may be taken as a good figure. The great difference in the efficiencies is due to the fact that fluid fuels require for combustion very little air above the theoretical quantity, while with the solid fuels fully twice the theoretical quantity must be admitted to dilute the products of combustion.

Correcting our previous results for these efficiencies, we have:

POUNDS OF WATER ACTUALLY EVAPORATED FROM 212° F., PER POUND OF FUEL.

Anthracite 9.0 Bituminous 8.8 Petroleum 18.9 Coal gas 18.8 Generator gas 2.9 Water gas 7.8

These figures agree closely with the results of experiments.

We will now consider the subject of cost.

The following cities have been selected, as manufacturing centers, termini of railroads, or fueling ports for steamers.

In the case of petroleum, as it is rarely shipped in the crude state, an approximation is made by adding to the cost at the nearest shipping port the freight charged on refined petroleum, and ten per cent. to cover duties and other charges.

Owing to the difficulty of obtaining prices, in some of the cities, there may be some errors.

COSTS. MARCH, 1884.

Anthracite Bituminous Coal gas per ton of per ton of per 1,000 2,240 lb. 2,240 lb. cubic feet.

New York $4 00 $4 25 $1 75 Chicago 5 00 3 50 1 25 New Orleans 6 00 3 50 3 00 San Francisco 12 00 7 50 3 00 London 5 00 3 00 0 75 Port Natal 12 50 11 00 Sydney 12 00 7 00 Valpariso 11 50 7 50

Generator Crude Water gas gas per 1,000 Petroleum per per 1,000 cubic feet. bbl. of 42 gal. cubic feet.

New York $0 45 $1 80 $0 50 Chicago 45 2 00 50 New Orleans 45 2 50 60 San Francisco 55 2 00 60 London 43 2 70 45 Port Natal Ap- 4 00 Ap- Sydney proxi- 4 50 proxi- Valparaiso mation. 3 00 mation.

In calculating the following table the specific gravity of coal gas is taken at 0.4; generator gas at 0.44; water gas at 0.48; petroleum, 0.8.

POUNDS OF FUEL FOR $1.00. MARCH, 1884.

Anthracite. Bituminous. Petroleum. Coal Water Generator gas gas. gas.

New York 560 527 156 18 74 76 Chicago 448 640 142 24 74 76 New Orleans 374 640 114 10 74 76 San Francisco 187 299 142 10 62 62 London 448 747 104 40 82 79 Port Natal 179 204 71 Ap- Ap- Sydney 187 320 63 proxi- proxi- Valparaiso 195 299 94 mate. mate.

These figures, multiplied by the actual evaporative powers as calculated, give:

POUNDS OF WATER EVAPORATED FROM 212° F. FOR $1.

Anthracite. Bituminous. Petroleum. Coal Generator Water gas gas. gas.

New York 5040 4643 2948 338 220 577 Chicago 4032 5638 2684 451 220 577 New Orleans 3366 5638 2155 188 220 577 San Francisco 1683 2634 2684 188 179 484 London 4032 6581 1966 751 228 640 Port Natal 1611 1797 1342 Ap- Ap- Sydney 1683 2819 1191 proxi- proxi- Valparaiso 1755 2634 1776 mate. mate.

RELATIVE COSTS.

Anthracite. Bituminous. Petroleum. Coal Generator Water gas gas. gas.

New York $1 00 $1 08 $1 71 $14 92 $22 90 $8 70 Chicago 1 00 71 1 50 8 72 18 30 7 00 New Orleans 1 00 59 1 56 17 90 15 30 5 80 San Francisco 1 00 64 1 50 8 75 9 40 3 50 London 1 00 61 2 05 7 16 17 70 6 30 Port Natal 1 00 90 1 21 Sydney 1 00 34 1 39 Valparaiso 1 00 44 1 03

These figures are very much against the fluid fuels, but there may be circumstances in which the benefits to be derived from their use will exceed the additional cost. It is difficult to make a comparison without considering particular cases, but for intermittent heating petroleum would probably be more economical, though for a steady fire coal holds its own.

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THE MANUFACTURE OF STEEL CASTINGS.

At the opening meeting for the winter session of the Iron and Steel Works Managers' Institute, held at Dudley on September 12, Mr. R. Smith-Casson in the chair, Mr. B.F. McCallem, of Glasgow, read a paper on "Steel Castings," which developed an interesting discussion upon steel casting practice. Mr. McCallem said that it was thirty years since the first crucible steel castings were made in Sheffield in the general way, and with one exception the method of manufacture was pretty much the same now as at that early date. The improvement was the employment of gas furnaces instead of the old coke holes for melting. Important economies had resulted from this introduction. Where before it required 3 tons of coke to melt 1 ton of steel, the same thing was now done with 35 cwt. of very poor slack. Though it was apparently easy to make crucible steel castings, it was not in reality easy to make a true steel, that was to say, to make a metal that contained only the correct proportions of carbon and silicon and manganese. The only real way to make crucible castings of true steel was to melt the proper proportions of cast steel scrap with the proper amounts of silicon and manganese to produce that chemical composition which was known to be necessary in best castings. It was in consequence of this difficulty that many makers resorted to the addition of hematite pigs. The Bessemer process was used much more extensively upon the Continent than in this country in the manufacture of castings. It seemed likely that Mr. Allen's agitator for agitating the steel in the ladle so as to remove the gases would be taken up largely for open-hearth castings and open-hearth mild steel, as it had a wonderful effect. The Wilson gas producer, working in conjunction with the open-hearth furnace, had recently produced some extremely wonderful results. In some large works, steel was by its aid being melted from slack which was previously absolutely a waste product. The method of making open-hearth steel castings might be varied greatly. The ordinary method generally practiced in this country was a modification of the Terre Noire process. The moulds employed were only of secondary importance to the making of the steel itself. Unless the mould was good, no matter how good the steel was, the casing was spoiled. The best composition which had been found for moulds was that of a large firm in Sheffield, but unfortunately it was rather expensive. A good steel casting ought to contain about 0.3 per cent. carbon and 0.3 per cent. of silicon and from 0.6 to 1 per cent. of manganese. Such a casting, if free from other impurities, would have a strength of between 30 and 40 tons, and on an 8 inch specimen would give an elongation of 20 per cent. or even more. It was possible by the Terre Noire process to produce by casting as good a piece of steel as could be made by any amount of rolling and hammering.

The chairman said that, as they had so high an authority as Mr. McCallem present, Staffordshire men would like to know his opinion upon the open hearth basic system, in which they were greatly interested.

Mr. McCallem said that he believed that the basic process would be worked successfully in this country in the open-hearth furnace before it would be in the converter. At the Brymbo Works, in Wales, he had seen the basic process worked very successfully in the open-hearth furnace; and he was recently informed by the manager that he was producing ingots at the remarkably low sum of 65s. per ton.

The chairman said that some samples which had been sent into Staffordshire from Brymbo for rolling into sheets had behaved admirably. He thought that the Patent Shaft and Axletree Company, at Wednesbury, were at the present moment putting down an open-hearth furnace on the basic process.