DR. POTTS'S PATENT IMPROVEMENTS IN HYDRAULIC ARCHITECTURE. [Patentee, Laurence Holker Potts, M.D. Patent dated, December 5, 1843; Specification enrolled, June 5, 1844.] ENGINEERS generally may not be pleased, perhaps, to be taught by a gentleman not of their own profession, so valuable a lesson in their art as that which forms the subject of the present patent; any more than the Judges and Bishops were wont to be pleased, when the late ingenious but eccentric Lord Stanhope boasted so often of teaching the one law, and the other divinity. But there are some, and these not the least eminent amongst them, who have not been slow to acknowledge that Dr. Potts has indeed taught them something worth knowing respecting the laying of submarine foundations,-something which they had no idea of before-and which they make no question may be turned to excellent practical account. Dr. Potts having been examined a week or two ago on the subject before the Harbour of Refuge Commission, Mr. Walker, the President of the Institution of Civil Engineers, who is a member of the Commission, with a candour and promptitude which do him infinite honour, avowed at once a most favourable opinion of the invention. He had seen with surprise the results of an experimental demonstration of Dr. Potts's method of sinking piles through sand-considered it very ingenious-and thought it might be tried with advantage in the construction of all piers and breakwaters not erected on hard or rocky bottoms. [The Commission not having yet made their Report, or published any of the evidence taken before them, we cannot quote Mr. Walker's precise words; but we give what we know to have been the substance of them.] Mr. Gordon, also, of whose ability as a light-house engineer our readers have had lately some striking proofs, has expressed himself on the subject in these terms :— "So confident am I of the economy, efficiency, and durability of the foundations which can be made by this invention, that I would undertake to adopt them in and through any sand banks, such as the Goodwin, and erect thereon such a light-house as I erected for the Light-house Commissioners of Jamaica, 115 feet high, by 19 feet base, or such as Her Majesty's Government employed me for, 140 feet high, by 25 feet base, for Bermuda," The peculiarity of the mode of construction ushered into the world under these favourable auspices, consists in a singularly felicitous application of pneumatic power to the sinking of the piles necessary for the erection of hydraulic structures. Instead of using solid piles, and driving them down by main force, as has been hitherto the usual practice, Dr. Potts makes use of hollow piles, and sinks them by means of atmospheric pressure that is to say, by pumping up from within each pile the sand, or other soft soil, of the included area, and producing a vacuum, which the pile instantly descends to occupy. Having witnessed, as Mr. Walker did, an actual trial of this mode of sinking piles, our surprise was not less than his at the ease and celerity with which the thing is accomplished. Compared with the old system of monkey driving, it has-if we may so speak—all the air of enchantment. Certainly there have not been many cleverer engineering feats than this accomplished, for many a day. The following details of the process we extract from the inventor's specification:- "Fig. 1 of the accompanying engravings represents the sinking of one of a series of hollow piles into a bank of sand covered with water. The pile A, which is open at the bottom, instead of being closed as in the case of a pile to be rammed, is first placed on end over the spot where it is to be fixed, and being allowed to drop through the water into the sand, the entrance of any air at the bottom is thereby effectually excluded. The top of the pile has then an air-tight cap, B, fitted upon it, and this cap is connected by means of a flexible tube, or hose, C, to a receiver D. E is a three-barrelled air-pump, which is connected by another flexible hose, to the receiver D, on the opposite side. The air-pumps being now set to work, as the air within the receiver and the hollow pile, and the intermediate connecting tube becomes exhausted or attenuated, a semiliquid mixture of sand and water flows up into the receiver, and as often as the receiver is filled, the contents are drawn off through a trap valve F at the bottom. As the sand is thus pumped up the pile descends by its own weight and by the pressure of the atmosphere to occupy the place of the solid materials removed. The air-pump is made introduced. This cap is kept tight in its seat by the pressure of the atmosphere with the help of an interposed gasket, or leather washer. To accelerate the descent of the pile, weights, H H, may be temporarily placed upon, or attached to the top of the cap. Should any stratum be encountered of too hard a nature to be penetrated by the above means, then boring tools, such as are used in the sinking of artesian wells, may be had recourse to, to break it up; and for the sake of greater facility in working these tools, the cap may be removed altogether during the operation. If one length of pile is not sufficient, two or more lengths may be made use of by screwing or otherwise joining them endwise together." Dr. Potts proceeds to observe that, though the preceding arrangements are "well-adapted for sinking piles of moderate diameter or section, and where the flow of water and sand, or other materials, from the exterior to the interior of the pile is free; but (that) when the sand or other material has such a consistency that the connexion between the interior and exterior is not free, or when the water has not an uninterrupted passage into the hollow pile, or when, from other causes, it may be expedient to use piles of such magnitude that the exhaustion of them would be a matter of difficulty, the process of excavation may nevertheless be effected on precisely the same principle,' in the following manner; that is to say, 44 By connecting a moveable tube of small size (which I call an elephant or operating trunk) to the exhausting apparatus, and passing it down through the then open pile or case, as represented on the right-hand side of fig. 1, but in this case the tube need not have any stuffing-box at top, as the stirring tools can be introduced when required through the open head of the pile or case. When extraordinary expedition is called for, there may be two or more such operating trunks employed at the same time, each trunk being connected by a separate flexible hose with the exhausting apparatus. And if the interior of the pile is large enough, persons may be sent down into it to guide the flexible shifting tube or tubes to all parts of the included area. In some cases it will be proper to provide the workmen with a tub or cobble, as represented in the figure to afford them a sure footing, and also to keep them afloat in the event of any rush upwards, or 'blowing up,' as it is termed of the sand or soil.' Fig. 2 exhibits both of the preceding plans applied in combination at a distance from the shore, the exhausting apparatus and workmen having been floated in a barge to the spot : "A is the smaller tubular pile, which is by the process of exhaustion to be itself permanently sunk into the sand. A2, the large open pile with the small operating trunk, I, applied inside of it, and a workman, K, to guide it. When the depth of a large open-topped pile, or series of piles, exceeds 30 feet, the receiver D must be placed within that distance of the water, sand, or other matter to be raised; and the contents of the receiver may be raised to the surface by similar means to those already described, or by any of the means ordinarily employed to raise the materials in sinking pipes or shafts for wells." The important part which the receiver D performs in both modes of operation is deserving of particular attention. Indeed, we doubt much whether, without this appendage, the apparatus could be long good for much; for were the raised sand not kept by this means quite apart from the pump-work, it would infallibly soon impede, and ultimately destroy its action. After the piles have been sunk by the means which have been described, Dr. Potts directs that they should be filled up with "concrete grouting, cement, or some other hard material or combination of materials." But "Before doing so, should the soil at the bottom be of a yielding description, it may be proper to consolidate and strengthen it above and about the foot of the pile, by pouring or forcing down the hollow pile, or through a small tube carried down within the hollow pile, such chemical solutions, or pastes, as the nature of the soil and previous experiment may point out to be best adapted for the purpose. For example, by analysing samples of the soil obtained from different depths it can be ascertained what its component parts are, and according as siliceous or calcareous or other materials predominate, it will be seen what class of chemical substances, simple or compound, will be best calculated to combine with and solidify them. And in like manner, it may be also ascertained by preliminary trials on a small scale, which, of various substances, simple or compound, will effect the desired induration, the most speedily and effectually." The specification then describes how any number of such piles as have been before described may be sunk in single rows close to one another, or in two or more rows, the piles of each row being placed opposite the joinings of the row in front of it-how sea walls may be formed of two ranges of such piles placed at a distance from each other, with a roadway of concrete between-how the construction of such works may be facilitated by making use of skeleton frames placed one above another, with orifices at the sides, through which the piles may be sunk-how in some cases, instead of having rows of piles close together, they may be sunk at intervals only, and connected sidewise by flat plates-&c. &c. Dr. Potts concludes by describing (as supplementary to this pneumatic process) a mode of forming submarine foundations, of stones thrown loosely together, and united, after they are under water, into a solid mass by the administration of cement in the state of dry powder : "The cement employed may be any of those known as hydraulic cements, and may be used either alone or intermixed with sand, stones, and shingle. And it may be delivered at the spot where it is required through a continuous tube from the surface of the water, or (by means of) canisters, having at bottom trap-doors for the escape of the powder." Dr. Potts claims this mode of applying cement to the consolidation of loose KNIGHT AND SONS' AIR-TIGHT STOPPER FOR AERATED LIQUOR BOTTLES. 437 masses of stone under water as also new; and we believe it to be so. Although not so strikingly ingenious as the pneumatic pile-sinking process, it may nevertheless be of great utility in cases, such as the Plymouth breakwater, where neither piling nor regular masonry can be had recourse to. MESSRS. KNIGHT AND SONS' AIR-TIGHT Messrs. Knight and Sons are the manufacturers of a "Patent portable apparatus for the production of aerated waters," of considerable note, of which it may not be out of place to say a word or two, before we proceed to describe how, by means of the present invention, these aerated waters when produced, may be bottled up, and drawn off as wanted, in any quantities, all equally brisk. The apparatus is that known as Bakewell's patent,' which has been much commended, and we think deservedly, as well for its extreme simplicity, as for its adaptability to the production of aerated liquors of all sorts, not only soda water, (of a much superior quality, however, to what is commonly sold under that name,) but every other kind of effervescing beverage, whether aperient, diuretic, tonic, antacid, lithotriptic, or peptic. The following engraving exhibits an elevation of a machine of this sort, of capacity enough to hold a gallon at a time. The interior construction of the machine may thus be briefly described. Within the external cylinder shown in the figure, which is of strong iron, there are two distinct earthenware vessels, one above the other; in the lower one the aerating gas (carbonic acid) is generated, and in the upper is contained the water or other liquid to be aerated. The generator, or lower vessel, is separated longitudinally by a diaphragm into two parts; the lower one contains the alkali (carbonate or sesquicarbonate of soda), and the other one the acid (dilute sulphuric), by the action of which on the alkali the aerating gas is generated. As long as the machine rests in a vertical position, the alkali and acid are kept distinct, and no action takes place; but by causing the machine to vibrate on its bearings in the two standards shown in the engraving, the acid is made to drop through a small orifice in the chamber containing it, into the Fig. 1. alkaline chamber beneath, on which a quantity of carbonic acid is instantly liberated, which is passed through a series of tubes till it enters and impregnates the water at top. The continual vibration of the machine agitating the water at the same time, enables it to absorb the gas almost as quickly as it is produced. A quarter of an hour is generally sufficient to complete the process, and impregnate the water to the extent of five atmospheres. On the top of the apparatus a pressure gauge is fixed, communicating with the water chamber; when this indicates by the rise of the mercury that a sufficient quantity of gas has been taken up, the vibrations are stopped, and the acrated liquid drawn off by the tap as wanted. Dr. Robert Venables, who has made this apparatus and its uses the leading subject of a very able and instructive Treatise on Aerated Waters,* gives the following useful information respecting the quantities of alkali and acid required for the production of soda water of dif Practical Directions for the Preparation of Aerated Waters, and the various Compounds of Carbonic Acid Gas, by Bakewell's Patent Apparatus; with observations on the pharmaceutical and therapeutical agencies, and their efficacy in the cure of some of the most important diseases of the human body, &c. 110 pp. 18mo. ferent strengths, and also the materials necessary for the generation of other descriptions of aerated water. "The charge of sesquicarbonate of soda for the impregnation of a gallon of water, under a pressure of five atmospheres, is about six ounces, and which for complete decomposition would require, omitting fractions, about three ounces five drachms and a half, by weight, of the common sulphuric acid. But if a highly impregnated fluid be constantly required, it is advisable to use rather more soda, say from half an ounce to an ounce. As the fluid is drawn off, the carbonic acid, relieved from the pressure, resumes a part of its elasticity, and rises above the water. This will be manifested by the fall of the pressure gauge. But if an excess of soda be used, a vibration or two will cause the gauge to rise again to its original number five.' The proportion of sulphuric acid for six ounces, is three cunces five drachms and a half; but it is better to have an excess of acid, by which the more perfect and complete decomposition of the sesquicarbonate of soda will be effected, and the resulting sulphate kept in solution, an advantage when cleaning out the apparatus. Seven ounces of sesquicarbonate of soda require about four ounces and one drachm by weight, consequently about six ounces would suffice. "If supercarbonated soda or magnesian water be the only beverage required, the requisite quantity of soda or magnesia may be mixed with the water to be aerated, and introduced into the aerator. "If lemonade be the object, this may be made in the usual way, and introduced into the aerator, and subjected to the pressure of the gas. Lemonade may also be made with the crystallized citric acid; half an ounce of which, dissolved in a gallon of water, in which some dried lemon peel has been macerated, or to which the requisite flavour has been communicated by the addition of a little of the essential oil of lemons, and sweetened with sugar, will form a most agreeable and grateful lemonade, which may be aerated with or without soda, as already explained." 66 When, however, it is the intention to use aerated water for several distinct and different purposes, it will be better to use simple water for the impregnation in the aerator, and expose the different matters to be carbonated to the action of the aerated water drawn off from the apparatus, in the flask, which being fitted with a valve stopple, may be detached, and the matters previously introduced into the flask, may be left exposed to the water surcharged with carbonic acid under the original pressure, for any length of time, as, from the peculiar construction, no gas can escape." By means of the invention (the airtight stopper) which Messrs. Knight and Sons have now registered, the aerated water, when it has been thus manufactured, may be transferred from the machine into bottles for the table; and either the whole or any portion of it may be drawn off as wanted. Fig. 1 of the following engravings is an external view of a bottle fitted with the air-tight stopper, and fig. 2 a section. A is a metal cap, which is strongly cemented to the top of the neck of the bottle. B is a three-way piece or barrel, which screws Fig. 2. Fig. 1. into the cap A; C is a plug, which fits into the barrel B, and as it is raised or lowered the three ways or passages, opens a b c. Fig. 3 shows it when closed. D is a cap to the plug C; E is a screw, with two or more threads, which passes through the cap D into the plug C, and by which, as it is turned round to the right or left, the plug is raised or lowered. F is a tube, which is fixed into the bottom of the barrel B, covering the mouth of the passage a, and reaches, when the barrel is screwed into its place, to the bottom of the bottle. G, an opening to the passage b, through which the bottle is charged with the aerated liquor, or with carbonic acid gas, to aerate a liquor not previously aerated; and through. which, also, the liquor is drawn off after the bottle has been duly charged; the nozzle being taken off in the former case, and screwed on in the latter. H is a screw cap, which covers the third way, c, by unscrewing which the atmospheric air can be let off when required. |