Chapter 6

This latter one, in contracting the bay, would contribute to increase the force of the current, which, throwing back at the ocean its mud and pebbles, would give us the depths of 15 and 20 meters indicated on the map of Beautemps-Beaupre.

This year, again, two projects have arisen; one of them due to Mr. Thuillard-Froideville, and the other to Mr. Hersent.

According to Mr. Hersent, it would be necessary to surround the Little Roadstead with an insubmersible dike built upon the rocky shoals, which would begin at Cape Heve (which it would consolidate) and end opposite the entrance to the port at 1,600 meters from the jetties. Through it there would be five passages. Afterward another dike would be constructed, starting from the shore and running to meet the jetty designed to inclose the Little Roadstead. On turning the angle at which it met the jetty it would be continued as far as to Berville. Finally, a third dike, running from Honfleur to Berville, would complete the system.

Mr. Hersent's project, which is one of the most remarkable of those that have been proposed, has one fault, and that is that it would require twelve years of work, and cost 158 million francs.

Mr. Thuillard-Froideville, completely renouncing masonry dikes as being too costly and taking too long to construct, proposes to inclose the Havre roadstead by means of floating breakwaters. As we have already seen, the use of these between Cape Heve and the Eclat shoals had already been proposed in 1845. As the project was abandoned, the models of these breakwaters are rare.

In Bouniceau's "Marine Constructions" we find a curious figure, a sort of open framework of clumsy form anchored in a singular manner, and surmounted by rooms for watchmen, semaphores, posts for the shipwrecked, etc. It is, indeed, the most complicated and most impracticable type that could be imagined.

Mr. Lewis' model, which was exhibited last year at the International Fisheries Exhibition, was, on the contrary, one of the simplest. It consisted of a strong piece of wood of nearly triangular section, the sharpest angle of which, being turned oceanward, was designed to cut the waves and cause them to break over it (Fig. 2). If, by favor of divine Providence, this breakwater, which presents absolutely plane surfaces to the shock and pressure of the waves, is not broken to fragments in the first tempest, it will certainly acquit itself of the _role_ for which the inventor destined it. When we have a system of resistance to the sea, anchored and facing a certain direction, and consequently not being able to revolve around its axis as vessels do, care must be taken not to give it entire surfaces.

Mr. Froideville's breakwater consists of a framework 25 meters in length, and 9 in height and width, and having the form of an irregular 5-sided prism (Fig. 3). The smallest side of the prism is designed to serve as a flat keel. The axis is formed of a metallic float, from whence start radii that form the skeleton of the framework, and that are designed for connecting the center with five long spruce beams that form the angles of the prism. To these beams are affixed the cross pieces that form the openwork sides. Five long pieces of wood parallel with the beams, but not so strong as they, protect the cross pieces and secure them against breakage in the middle. All the angles of the breakwater and all points of juncture of the pieces are protected with iron, and it is in order to counterbalance the weight of all this iron that the central float is used. Parallel with this first breakwater, there are two other and smaller ones, which are designed for reducing the effect of rolling as much as possible. Reduced to a single float, the breakwater might remain under the waves too long, but, owing to the two others, it rights itself, warps around, and always presents the spur of its sharp roof to the wave.

In order to prevent the breakwaters from clashing against each other, they are united end to end in a very simple and ingenious manner. From each of them there starts a deeply inserted iron bar which terminates in a journal that permits the breakwater to oscillate. Between these two bars there is a sort of swivel, whose pieces, in playing upon one another, give the breakwaters elasticity, while always holding them apart (Fig. 4). From each side of the swivel start the branches of a stirrup iron to which the anchorage chain is attached. This latter is of steel, without solderings, and it is so perfectly constructed that no breakage need be feared. To the other extremity of the chain is attached an anchor having two flukes, which both engage with the bottom.

Mr. Froideville proposes to set up two lines of these breakwaters, for a length of about 7½ kilometers, starting at the north from Cape Heve, taking in depths of 15 meters (the best that are found in the Little Roadstead), passing in front of the Eclat shoal and the heights, and ending opposite the entrance of the present port.

The first row is designed for breaking the force of the waves, and the second for lending its aid in times of high tempests, and stopping the surge that has escaped from the first.

The extreme simplicity of this project has permitted its promoter to affirm that in a few months, and with nine millions, he can inclose the Havre roadstead.

The Little Roadstead, being thenceforward protected, will become an excellent port of refuge in bad weather. In addition, a system of lighters, or, better, a few floats connected with the shore and forming a rock, will permit vessels to take on their cargoes with great rapidity.

Mr. Froideville's project presents the further advantage of rendering it easier to put the port of Havre quickly in defense. A certain number of floating batteries, anchored behind the breakwaters and protecting the advances of torpedo boats by means of their firing, would make a formidable defense. Not having to perform any evolutions, they might without danger be invested with armor plate thicker than that of ordinary ironclads. In order to complete the system, there might be erected upon the Eclat shoal an ironclad fort like that which defends the entrance of Portsmouth.

An English chronicler of the fourteenth century, in speaking of his country, places it above all others, and declares that men are handsomer, whiter, and purer blooded there than elsewhere, and he says that this is so "because it is so." We would not like to imitate his naive reasoning, and yet, for defending the very original system proposed by Mr. Froideville, we have only our conviction, which we share, moreover, with a large number of sea-faring men and engineers. Mathematics are powerless to predict to us with accuracy the manner in which the floating breakwaters will behave, but experiment remains. Let the promoter of the project, then, be given authority to inclose a few hundred meters, and if, as we suppose, the breakwaters shall remain immovable in a northwester, a maritime revolution will have been brought about.--_La Nature._

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IMPROVED CATCH BASIN.

In 1882, M. Bacle published in _Le Génie Civil_ a study of the sewer systems in some of the large foreign cities. There may be found there a description of the Liernur system at Amsterdam, Leyden, and Dordrecht, in Holland, and in certain cities of Germany and the United States.

This system consists in the employment of two distinct systems of ducts, one for the discharges from water-closets and the other for household wastes, rain water, and the discharges from factories when sufficiently purified. This arrangement allows the employment of sewers of small section, provided that it shall be unnecessary to enter them for the purpose of cleansing them. It has been necessary, therefore, to provide inlets with a separating apparatus called "gully" or "catch basin," which retains as completely as possible all solid matter, mud, excrement, and _debris_ of every kind which maybe floated in by street washing or by rain-water, and which may be capable of causing stoppages in the sewers, the choking up being followed by fermentation and the emanation of noxious vapors.

M.C. Pieper of Berlin suggests a device for a catch basin, which appears to meet the requirements. It is in the form of a cylindrical metal box, enlarged in its upper section to receive a filtering cylinder of perforated sheet iron, which occupies almost the upper half of the device and rests upon the smaller lower part. The entire apparatus is covered by a movable funnel, through which enter water and any rubbish which it may carry with it. From one side a tube allows the liquid to be discharged, while a siphon placed on the opposite side serves the same purpose under certain circumstances, as will be explained.

Figure 1 represents the apparatus discharging under normal conditions. The heavy matter, sand, stones, etc., falls to the bottom into a receptacle which can be lifted out from time to time and emptied. The lighter buoyant matters, straw, vegetable _debris_, paper, etc., remain at the surface, and are retained by the filter; the water passing through the holes in the sheet iron rushes in a filtered condition through the annular space which exists in the upper part between the two cylinders, and escapes by the waste-pipe when the water reaches a proper level. If at a given moment the quantity of water flowing in is too much to be discharged through this waste-pipe, the level of the water mounts in the cylinder until it reaches the top of the siphon. Immediately the siphon comes into play and empties the upper part of the apparatus, and the filtered water contained in the annular space already mentioned quickly re-enters the cylinder through the perforated sheet iron, and in so doing cleans out the perforations with considerable energy. This second period is represented in the second figure.

The mouth of the siphon being placed above the movable basket, the heavy matters contained in the latter are not in the least disturbed, and the metallic screen placed over the mouth prevents the entrance of any floating matters. When siphonic action ceases, the water in the short arm of the siphon empties itself into the main receptacle, and by so doing cleanses the screen. During a rain or the washing of the streets, the siphon can work in concurrence with the ordinary discharge-pipe. It is evident of course that these two--pipes can be placed on the same side of the apparatus, if this prove the most convenient arrangement.

We will add that this apparatus can be applied not only to the Liernur system, but also can be used for preventing the entrance of obstructions into sewers of the ordinary type, where the grade is small or where the quantity of water is insufficient; and if we adopt the system of "everything to the sewer," can we not find in the employment of this apparatus an element for the realization of the famous formula, "Always in circulation, and never in stagnation?"--_Le Génie Civil._

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[Concluded from SUPPLEMENT No. 454, page 7249.]

WATER-POWER WITH HIGH PRESSURES AND WROUGHT-IRON WATER-PIPE.

By HAMILTON SMITH, JR., M. Am. Soc. C.E.

METHODS OF CONDUCTING WATER AND TRANSMITTING POWER.

A description of the mode of using water-power for driving the North Bloomfield tunnel in California, some years since, will give a good illustration of some of the advantages of the hurdy-gurdy. This tunnel was originally about 8,000 feet long, through a slate highly metamorphosed, with its general line passing under a good-sized stream, at a depth of about 190 feet. There were eight working-shafts, each about 200 feet deep, which, with the lower entrance or portal, gave sixteen working faces. Diamond drills were used at the lower heading requiring power; the other fifteen headings were driven by hand-work. It was uncertain how much water would be encountered; but from the location, it was evident that a large quantity might be struck in any shaft, and hence it became necessary to have ample power at hand at each opening, in readiness for such an emergency. A pipe main was laid along the general line of the tunnel, with its pen-stock 285 feet vertical above the surface at the upper shaft, and 549 feet above the lowest shaft. It was made of single riveted sheet-iron, of No. 14 (Birmingham) gauge, in lengths of 20 feet, put together stove-pipe fashion, with the joints made tight by cloth tarred strips and pine wedges. This pipe had a diameter of 15 inches at the pen-stock, diminishing from this to 13, 11, and 7 inches at its lower end. From it, short branches, 7 inches in diameter, were extended to the several shafts. It was in one place carried across the stream by a light suspension bridge, some 150 feet long, the trunk of a tree on each side forming a convenient tower. The aggregate length of the main and branches was 9,960 feet, with some 2,500 feet additional, for the branch to the diamond drills. The pipe was laid on the surface of the ground, its only protection being in places a couple of 1½-inch planks tacked together, and placed over it; the range of temperature was from 10 degrees to 107 degrees Fahr. (in the shade). It was inspected by the foreman of the tunnel-work as he daily walked over the line; besides the occasional driving of a few wedges and putting on a band or two, it gave no trouble from leakage, which probably for its entire length did not amount to more than an average of 3 or 4 cubic feet a minute; from time to time, a little sawdust was put into the pen-stock. Three stop-gates were placed on the main, and a separate stop-gate at each shaft, operated by a fine-threaded screw, so that the water could be cut off when desired.

Fig. 13 shows the arrangement of the machinery for hoisting and pumping, which was identical at the several shafts, except that the hurdy-gurdies varied from 16½ feet in diameter at the upper shaft to 21 feet at the lowest shaft. The water-wheel moved only in one direction; the pinion on the wheel-shaft drove the spur-wheel, to which the pitman of the pump-bob was attached. On the spur-wheel shaft was a friction-gear, driving the hoisting-reel; this reel was mounted on sliding blocks, so that hoisting was done by putting it in gear, the empty load being dropped by a friction-band. Changing the size of the water-wheel as the pressure increased permitted the use of the same pattern of machinery at the different shafts. The water was brought to the wheel by a discharge-pipe, some nine feet long, having a vertical movement by ball-and-socket joint, so that at pleasure, by dropping the pipe, the machinery could be run at various speeds, or entirely stopped. At the end of this discharge-pipe was a cast tapered nozzle, about 3½ inches in diameter, in which was inserted a ring of saw-plate steel having the desired diameter, and which was held in place by an annular screw-cap. By changing the ring, which only required a few moments' time, any desired amount of water, up to 3 or 4 cubic feet a second, could be discharged against the wheel. The stop-gate was left wide open while the machinery was running. The pumping was done by eighteen pumps, of Cornish pattern; the largest amount of water pumped from any one shaft was something over 30 cubic feet a minute; the power at hand, however, was ample to pump more than twice that quantity. It was rather curious at, this shaft to see more water coming from the pumps than was used on the wheel. The two diamond drills were driven by a small hurdy-gurdy set on the rear of the drill carriage. This, but at another tunnel, was afterward modified by placing a separate hurdy-gurdy on a sleeve on each drill-rod; the advance movement of the drill being given by hydrostatic pressure on an annular piston, thus doing away with all gearing. These eight sets of machinery were run for nearly 2½ years' time; the only break being that of a spur-wheel, doubtless caused by the careless dropping of a steel bar between it and its pinion. Aside from this accident, practically not a dollar was spent for repairs, and the machinery, including the pipe, was in about as good order when the tunnel was finished as when it was first erected. One man, on a twelve hour shift, operated the machinery at each shaft, besides dumping the cars; two men kept the 18 pumps on the line in order, the principal work being in keeping the suction-pipes for the down-grade headings tight; thus a force of 18 men was only required for the eight shafts. The cost of the pipe, gates, etc., when put in place, was $14,631, and of the machinery about $60,000.

At the Idaho gold quartz mine, situated near Grass Valley, California, water-power has been introduced during the past year (1883), taking the place of steam. The supply main is of wrought-iron, 22 inches in diameter, 8,764 feet long, buried in the ground below frost-line. The joints, as a rule, are riveted together, with occasional lead joints to admit of slight movements in the pipe.[4] The pipe was coated by placing each joint in a bath of boiling tar and asphaltum; to insure the most thorough coating, it is necessary to keep the pipe for ten or fifteen minutes in the boiling mixture. A cast-iron stop-gate is placed at the lower end of the main, and also one at each of the branches. Cast-iron man-holes are attached to the main, which, although they have given no trouble in this particular case, are very objectionable for high pressures, as it is difficult to avoid ruptures with cast and wrought-iron combined, owing to the great difference in the elasticity of the two metals. The long seams of this pipe are double-riveted, and the round seams single riveted; at the lower end, iron of No. 6 gauge is used. From the end of the main, the water is led to the several wheels by branches of smaller diameter.

[Footnote 4: With buried wrought-iron pipe this precaution is unnecessary, as the elasticity of the iron will admit of the movement due to changes of temperature, without injury to the rivets.]

The water is delivered at the hoisting-wheel with a total head of 542.6 feet. For power and for mill uses, etc., the required supply is about 8 cubic feet a second; this draught reduces the effective head to say 523 feet.

The work done consists in driving the following described machinery:

A large air-compressor--2 cylinders, double acting, air compressed to 75 pounds--requiring about 140 horse-power.

A line of Cornish pumps, forcing the water from a depth of 1,450 feet vertical; 12-inch plungers for upper 800 feet, 6-inch plungers for lower 650 feet, with 6-foot stroke, requiring from 55 to 70 horse-power.

Hoisting from a double-compartment shaft--two connected winding reels, moving separate cages--requiring 35 horse-power, or more.

A few small machine-tools and smithy forges, requiring 3 or 4 horse-power.

A 35-stamp mill, with concentrating apparatus, etc., requiring about 70 horse-power.

The total amount of power required being say 320 horse-power, for which seven Pelton hurdy-gurdy wheels are employed.

The power in all cases is transmitted by systems of Manila rope belting; the rope is 2 inches in diameter; the grooves in the sheaves or pulleys are slightly oval, so that the rope does not go quite to the bottom; the ropes are horizontal, and run very slack (no tighteners), with no appreciable slip; the splices are made very long, to obtain uniformity in diameter.

This method of transmitting power appears to work most perfectly and has given excellent satisfaction. It is thought, at the Idaho, to be greatly preferable to the gearing formerly in use when the works were driven by steam (for such work as pumping or hoisting, leather or rubber belting is never used), besides being much cheaper in first cost.

The wheel driving the air-compressor is 6 feet in diameter, running 300 turns[5] per minute, with 1-15/18-inch nozzle; three ropes are used from the wheel shaft to the counter-shaft, and six ropes from the latter to the fly-wheel shaft.

[Footnote 5: The revolutions per minute, of these wheels, as here given, are only approximate, as the design was to have the bucket speed=½ 2(gh)^{½}.]

For driving the pumps, there are two water-wheels, set on the same shaft, one 5 feet and the other 7 feet in diameter, either of which can be used at will, thus permitting different rates of speed; two nozzles are placed on each wheel, so that if necessary the power can at any time be doubled. The smaller wheel has a 1-1/4 inch nozzle, and runs 360 turns a minute; the larger has 1-1/8-inch nozzle, and makes 270 turns a minute. There are two ropes from the wheel-shaft to a counter-shaft, and four ropes to the fly-wheel shaft, on which is the pinion driving the spur-wheel attached to the pitman of the pump-bob. Hoisting is done by two wheels placed side by side on the same shaft, the buckets and nozzle of each wheel being placed in opposite directions. Both wheels are 8 feet in diameter, with 15/16-inch nozzles, and make at full speed about 225 turns a minute. Reversing the movement of the shaft is done by shutting off water from one wheel, and turning water on the other wheel; the two water-gates for these nozzles are quickly opened or closed by hydrostatic pressure, afforded from the water main. In addition to the usual brakes on the winding-reels, a brake is placed on the wheel-shaft, so that it can be stopped in a very short period of time.

The shock to the pipe by the almost instantaneous cutting off the water at these hoisting-wheels (nearly one cubic foot per second) has not apparently had any injurious, effect. To lessen this shock, a compensating balance was designed, but which is not now in use. A wheel, of small diameter, is used for the smithy, etc., running at a very high velocity. The wheel driving the stamp-mill is 6 feet in diameter, makes 300 revolutions a minute, and is supplied through a 1-3/16 inch nozzle. The head of water at this point is a few feet greater than at the other wheels. Power is transmitted from the hoisting and mill-wheel shafts by two and four ropes, the same as with the pumping rig. The amount of work done, or of water used, has not been carefully determined; judging from the indicator cards taken from the old steam-engines, the managers of the Idaho believe that an efficiency of fully 80 per cent. of the theoretic power of the water is obtained on the main driving-shafts of the machinery. The substitution of water for steam-power has resulted in a large saving of expense. Although the hills near by are covered with fine forests, thus making wood cheap, and although a round price is charged for water by the company furnishing it, the cost of the water is considerably less than that of the wood formerly used as fuel. The cost of attendance is altogether in favor of the water-wheels, which hardly require any attention. The cost of the change from steam to water-power was $46,496.32.

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TEXAS CREEK PIPE AND AQUEDUCT.