va ze micse1 12 The act of expulsion might take ▲ minute. Borewering ones if the ejector and The Treasure I ne povel to get Ünder such a system of election and french. I muntess I to not see how the hygienics i ne sen na e arv han sacsitory. With proper samning, inu seansing i twat, de min and subsoil water fi Twi, framed if is evige ae manner described, could be alowed no pass no mr rocks, vers, or seas with impunity. I must e kim:ttei. I nink that compressed air is peculiarly Vail kapted is a motor for he propulsion of sewage. We might kiince severni sons in support of this assertion. We will ntent meseives by stating the following in the meantime:— It is, is ve have just seen, me of Nature's agents for the purification of viste rganic matters. It is an agent of which we have an mimited supply in the atmosphere ironi is 3. It is a motor dance as produced, can be conveyed and divbied amongst any number of stations near to or far apart from each other, without any significant or appreciable loss. The fcLowing comparison of the friction of water and sir under similar conditions, as to the fameter and length of pipe and velocity of current, will give you an idea of the smallness of the loss occasioned by passing air, at even comparatively high velocities, through pipes: Given, a pipe 1 mile long and 12 inches diameter, the head required to pass (2) Water, at a velocity of 4 ft. per second, would be 404 ft. of water. B) (c) Air (d), 9 ft. 204-6 ft. 0-03 ft. 0.15 ft. This comparison shows that, as compared with water, the friction of air is as 1 to 1336 about! The heads stated above are calculated from Box's formula, as given in his work on "Hydraulics," for cases (a) and (b), and from formula given in his treatise on "Heat" for cases (c) and (d). The practical truth of the above statement as to the insignificant loss by friction in the flow of air through pipes has been abundantly proved by experience in collieries, and also in the Mont Cenis Tunnel boring operations.* * See Simm's "Practical Tunnelling." Third edition. (4) It is a motor, as compared with steam, that is unobjectionable on account of the absence of heat radiating from the pipes conveying it, as the temperature of the air conveyed is always the same as, or very nearly, that of the outside atmosphere. (5) Where water power is obtainable within a reasonable distance from a town (and there are a great number of such places) proposed to be sewered upon my system, the compressors could be worked by turbines. This would do away with the charge for fuel altogether, and turbine power thus utilized could be transmitted to long distances, and made to operate in many places where ordinary pumping could not be adopted without the use of steam power; and the compressors used in connection with any scheme designed in accordance with my sewerage system may be fixed at one place to supply the air through pipes leading to the several ejector stations; or, if found more convenient, the compressors may be separated, and made to discharge the compressed air at two or more points of the system of air-mains. In the latter case, the motor for compressing the air may be either steam or water, or these may be combined-i.e., steam power compressing air at one place, and water through turbine power compressing air at another place. I am aware that compressed air is looked upon by engineers as an expensive motor to produce and utilize, and no doubt there have been sufficient reasons, in the imperfections of air-compressing machinery and in the losses arising from the application of the air to the driving of machines, to impress engineers with its expense. But as air-compression is better understood so will the machines for its production become more perfect in design and economy of working; and rapid strides have been made of late years in the development of air-compressors. To my mind the Sturgeon "High Speed," which I have been using in my trials at Wrexham, and which was manufactured by Messrs. Clayton, Howlett, & Co., London, and the Sturgeon "Trunk " Compressor, manufactured by Messrs. Thwaites Brothers, Bradford—an illustration of which is given at Fig. 12—appear, especially the latter, theoretically to be well designed for the economical compression of air. Again, in the raising of liquids upon my system the ejectors are not to be regarded as pumps in which the motor has to overcome the friction of glands, plungers, and all moving parts necessary to their working, because in the ejector the air has nothing more to do than to force out directly, without the intervention of any piston or plunger, the liquid contained therein; and, after allowing for all losses in the compression of air, I am satisfied, after careful investigation of various recorded results, that the cost of raising sewage and other liquids upon my system will compare very favourably with those of the best class of ordinary pumping engines. It would lengthen this paper too much if I were to give examples of the power required to work any given sewerage scheme upon my system, but I may say that I propose to go minutely into the question of cost in a work that will shortly be published, treating of pneumatic sewerage. I may, however, state here that by using some such steam generator as Messrs. Thwaites, Stuart, and Sturgeons' (of Bradford) Patent "Central Feed Vertical Boiler," which is intended to use up the solid waste refuse of towns, in the shape of ashes, &c., steam may be produced at little or no cost. In this way the solid wastes could be subjected to "cremation," and in the process steam could be generated, to compress air, to eject the liquid wastes of our towns away therefrom, as rapidly, practically, as they are discharged into the sewers. I might also add that my pneumatic system is applicable to mansions, hospitals, asylums, military depots, hotels, offices, workshops, prisons, schools, mills, factories, and such like buildings, each of which could be provided with its own distinct ejector, into which the sewage and drainage of the place could be made to gravitate rapidly when fresh, so that it may be forced therefrom into the existing sewerage system of the town or district, and thereby prevent the generation of sewage gas within such buildings and their premises, and at the same time cut off all communication for the flow of poisonous sewer gases from the main sewer. Fig. 13 is intended to show (1) how a mansion having its drainage now in direct communication with a public sewage-gasproducing sewer may be disconnected therefrom by the interposition of a pneumatic ejector; and (2) how the drainage of the same mansion could be still further improved, by placing the ejector a little deeper in the ground, as shown by the dotted lines, for the all-important sanitary purpose of giving to the small drainage pipes steeper gradients to make them "self-cleansing," whilst they discharge the sewage fresh as it is produced, as all sewer-pipes should do. The ejector, being automatic and worked by fresh atmospheric air, would discharge the sewage noiselessly and innocuously into the public sewer, VOL. XII.-No. 1. 2A |