Difference-revolutions...... 27485 By gauge on force pipe..... 141.372 In regard to the capacity guaranteed for the engines, I am inclined to believe, in view of the stipulated dimensions of pumps and piston speed, that the incorporation in the contract of four millions (4,000,000) gallons capacity was unintentional, as the prescribed data of the contract prohibits this discharge. You will observe that both engines have exceeded the contract duty, one by nearly two millions, and the other by more than eight and one-half millions. In the general report, which I shall submit at an early date, will be given all the data taken during the trials, together with an inquiry into the precise performance of the engine, as developed from the indicator diagrams. A PULVERULENT lubricating material for axles, shafts, &c., is prepared by Herr Drechsler, of Dresden, thus: The finest graphite powder is worked up thoroughly with egg-white, or yellow, or both, to a firm dough, which, in a metallic vessel, is kept in a vessel of boiling water, till the egg-white and yellow are fully coagulated. The mass is then dried at 90° C., so thoroughly, that it can be bruised or 0169 stamped to powder. This powder is applied to a slowly-revolving axle or shaft, till axle and bush take the peculiar dark shine of graphite. 32.437 2.3 178.8921 STREET CLEANSING IN PARIS. By M. VAISSIERE. From Foreign Abstracts of Institution of Civil Engineers. The cleansing of the public thorough- ways employed when it is desired to fares in Paris, formerly undertaken by destroy the germs of putrid fermentathe Prefect of Police, is now a function of tion. It is used at a strength of about the Prefect of the Seine. The staff con-, say a gallon of the acid to 40 gallons sists of two chief engineers, one for each of water. At strengths of and group of arrondissements, one group be- it gives good results for watering once ing subdivided into three sections, each or twice a week in summer those parts under the charge of an executive engineer; of the Halles Centrales liable to infecand the other into five sections, similarly tion. It is even used as low as 1 for supervised. These sectional engineers watering streets and gutters. Hydrohave under them fifty-one superintend- chloric acid is applied to urinals and ents and sixty-one overseers, whose em- slaughterhouses. In places much enployment imposes upon the municipal crusted with tartar it is used at a budget an annual cost of 260,000 francs. strength of t. Lowered to it cleans The scavenging plant is kept in a central smooth walls and flags efficiently. depot, where materials of every descrip- ordinary rinsings a strength of suffition are stored and classified, for ordi- ces. It leaves a disagreeable odor benary and extraordinary service, when hind, which is, however, quickly dissisnow and ice render additional assist-pated. Mirbanic acid (nitro-benzide) is ants necessary. more energetic than the foregoing, but The depots contain supplies of chlor- it produces a disagreeable smell of bitide of lime, sulphate of zinc, sulphate of ter almonds, and leaves a white film which iron, and carbolic acid, as disinfectants; has to be washed off. It is used at the and hydrochloric acid, nitro-benzide same strengths as hydrochloric acid. (acide de mirbane), as cleansing agents. The annual cost for plant and disinfectThe chloride of lime, of a strength ing materials of all descriptions is £8,800 of 100° to 105°, 105, is successfully (220,000 francs). employed for the disinfecting of places tainted with urine or fæcal matter, also for the cleansing of gutters carrying sewage water. Sulphate of iron and sulphate of zinc are both used under the same conditions. Sulphate of iron possesses the disadvantage of rusting objects to which it is applied. Sulphate of zinc is stronger in its action, but costs a little more. It produces no smell, nor does it leave any trace. It is much employed in summer for washing and watering the basements of the Halles Centrales, used for fish, poultry and offal. At a strength of, and mixed with 3 per cent. of sulphate of copper, sulphate of zinc makes a good disinfecting liquor, which preserves its qualities a long time and is of great use in private houses. Carbolic acid is not, strictly speaking, a disinfectant; it does not act like chloride on putrid matter, but arrests and prevents fermentation, doubtless by destroying the spores. It is, therefore, al The engineers of the city of Paris are also charged with the sweeping of the roads, an area of 12,916,800 square yards being cleaned between 3 and 6 A. m. in summer and between 4 and 7 in winter. The carts for removing the public and private refuse work from 6 to 8 A. M. in summer and from 7 to 9 in the winter. The filling of each cart is attended to by the driver aided by two shovelers, the latter having to provide during the rest of the day supplemental sweepings wherever required, to rinse the gutters twice a day, and to clear and disinfect urinals, &c. These matters are ordinarily finished by 4 o'clock in the afternoon, except in unfavorable weather. The engineers have all at their disposal a staff of: fr. c. fr. c. 2,200 men at from 2 50 to 40 per day. 950 women 66 0 20 to 0 25 per hour. 30 children (boys) at 0 20 hour. per In addition there are one hundred and ninety mechanical sweepers, and as each removing the snow the General Omnibus machine represents the effective work of Company are bound by their concession ten men, the total scavenging staff may to furnish fifty wagons, and carts are be considered as composed of nearly five specially arranged for with the providers thousand laborers. of sand and gravel at the beginning of The mechanical sweepers which, after winter, the contractors for maintaining numerous trials and much hesitation, the public roads being also bound to have been introduced into Paris, are the hold their carts at the disposition of the English machine, improved by M. Sohy, sectional engineers. In certain cases and the machine of M. Blot, the former the half-melted snow is swept into the being preferred. The mechanism of sewers, especially those carrying warm both is simple, works with regularity, water. Melting by steam has been and occupies little space; it consists of a framework upon two wheels, with a seat for the driver. At the back is placed the sweeping apparatus, composed of an inclined circular bass broom, actuated by gearing driven from one of the wheels of the carriage. By means of a clutch the driver can from his seat easily put the broom in or out of gear. The machine is employed in all weathers, and works as well on paved roads as upon macadam or asphalt. Each machine weighs rather over 14 cwt., and can be drawn by one horse. It sweeps about 6,578 square yards per hour. The cost of the machine is £40, and its annual maintenance, exclusive of renewals of the brush, £8. The cost of a new brush is about £2 16s. Both hose and carts are used for wa(70 francs), which will work for from tering the thoroughfares, the former for one hundred and sixty to one hundred the boulevards, the avenues, and a cerand eighty hours. tain number of first-class streets. tried, when a continuous jet was introduced into a mass of banked snow, but it melted very slowly at first, and the melting ceased after the cavity had increased to a certain size. Two descriptions of snow plough are kept in store, one for manual, the other for horse power; but they have never been used, as the coating of snow seldom attains sufficient thickness, and as it is too quickly compressed and hardened by the traffic. As a rule the sum allowed in the budget, about £7,000, suffices for the extra labor incurred; but occasionally severe winters cause this to be greatly exceeded, as in 1875-76, when the increase amounted to £8,000. The The Paris mud no longer possesses watering plant belongs to the municipalithe manurial strength of former times, ty. Three descriptions of carts are in and in consequence the receipts derived use, two heavy wooden ones are now beby the municipality from this source ing superseded by the third, Sohy's cart, have greatly diminished. It is at present disposed of by public tender to responsible contractors for terms of about four years. For its removal there are daily employed five hundred and twenty carts, and nine hundred and eighty horses. The average bulk removed per day is about 2,223 cubic yards (1,700 cubic meters). made of sheet iron. The carts contain 220, 242 and 286 gallons respectively, and will water from 2,400 to 3,350 square yards. The watering by hose is attended to by the ordinary street cleaners, who can easily water 24,000 square yards in thirty-five minutes, deducting the time necessary to connect the apparatus with the mains. There are three When a fall of snow occurs, attention hundred and twenty-two water carts, is first directed to clearing the footpaths which on the average disperse 1,311,200 and crossings, so as to insure uninter- gallons of water over a surface of 7,139,rupted circulation of foot passengers. 163 square yards. A surface of 2,783-, The town scavengers sand the roads 092 square yards is watered by hose, wherever it is necessary for the carriage and this system is being greatly develtraffic. At the same time numerous aux- oped on account of its convenience and iliaries are organized to remove the snow cheapness. The annual cost of waterfrom the principal thoroughfares, in the ing is £18,000.-Annales des Ponts et order of their relative importance. For Chaussées. REPORTS OF ENGINEERING SOCIETIES. AMERICAN SOCIETY OF CIVIL ENGI barden by cooling. These, instead of gaining their strength slowly, like those of class two, become hard at once. Shellac is a good THFERME TAN January and February issues example of a cement of this kind. of Transactions, contain: Paper No. 214. The Strongest of the Bronzes; a Newly Discovered Alloy of Maximum Strength," by R. H. Thurston. No. 215. Renewal of Foundation and Transfer of a Lighthouse in Pascagoula Har bor," by J. W. Putnam. No. 216. "The Sewerage of Memphis," by F. S. Odell. The papers are fully illustrated and the discussions of the latter paper are of unusual in terest. POLYTEC OLYTECHNIC ASSOCIATION OF THE AMERICAN INSTITUTE.-At the meeting of the 17th March, the paper for the evening was by Prof. Plympton upon the aneroid barometer. This instrument has been greatly misunder stood, and has been much abused because peo ple, in buying it, have often supposed that they would be able, by inspection, to read off the elevations at which they made their observations, in the same way that they would note the temperature upon a thermometer. Like the mercurial instrument, it is a measure of the pressure of the atmosphere at any given time. In torrid zones, where the variations of pressure are sudden, especially those just preceding severe storms of wind, &c., the mercurial instrument does not indicate with sufficient rapidity. It is an accurate balance, though rather slow to swing. Its numerous disadvantages as a portable instrument were mentioned, and its construction illustrated experimentally. The construction of the aneroid was then described, and drawings were made upon the board. Almost a dozen different styles and sizes of instruments were then exhibited, from the 5-inch instrument to the delicate affair no larger than a watch. The paper of March 24th was upon glass and cements, by Dr. John Phin, of the American Journal of Microscopy. Cements are to be divided into four classes, according as they dry, congeal by oxydation, harden by cooling, or set" by other chemical changes. First are those which harden by evaporation. Under this head may be classed paste, mucilage and their varieties. Glues to a certain extent dry. The second class includes the oils. These are said to dry, but it is not by evaporation. They lose nothing, but absorb oxygen from the air. The cement weighs more after hardening than when first applied. Cements which congeal by oxydization cannot be treated in the same way as those of the first class. They require a larger time to handle. The hardening goes on from the outside inward. For example, mend a piece of porcelain with one of these cements. Test it in a few days, and although the outside will be hard the inside will not appear to have dried in the least, and will have no tenacity. Leave it for six months, and it will be very strong. Thirdly, we have those cements which China put together with melted shellac is extremely strong. A fourth class of cements may be represented by plaster of Paris. This is the type of an extensive class, including the whole line of mortars and hydraulic cements on which depend our great engineering works, and even the houses in which we live. It forms a chemical compound combination with water first, and then more slowly hardens by drying a part of the water evaporating. In order to use a cement successfully we must know to what class it belongs and treat it accordingly. Next, we must know how to put it on. In no case should it be used in a large quantity. The less the better is a good rule to follow. In mortar we mingle sand, which makes the actual thickness of the lime between the stony surfaces in all cases very slight, however much mortar we may employ. In the use of glue this is not practiced or necessary. The joints made by carpenters are good examples of the minute quantity of a cement which is necessary. Place a well-made glued joint on the edge, and it is almost impossible to find the lines of glue. Its position is mainly discovered by the direction of the grain of the wood. Intimate contact between the cement and the edges is necessary. This is not easy, on account of the layer of air which adheres to all bodies. This layer of air is what causes needles to float when carefully placed upon the surface of water. When an object is warmed the film of air is easily moved, the hot needle sinks, and to the hot body the cement will adhere easily. It is faulty for this reason, that in gluing it is needful to have the work warmed. The rubbing of the surfaces together gets rid of the air, and then not only with glue, but with all cements, the surfaces must be pressed closely together, Common glue has most enormous strength and adhesive powers if it is good. But to be good it must not have been injured in the making by decomposition, to which the material and the glue itself are peculiarly subject. Here the lecturer detailed at some length the process of glue making, and said that if glue was not pleasant to both taste and smell it would not be strong. If not offensive, it could be trusted to hold wood more strongly than its own fibers. The strongest known glue is that made from the skins and sounds of fishes, and the strongest of this class is made in Lapland from the skin of a perch. The Laplanders use it in making their bows, which are both strong and durable. In making it their cold climate is greatly in their favor; here a fish skin will begin to undergo decomposition before it can be dried. In making it the skins are put into a bladder, which answers for a water bath, and heated in water until a sort of glue results. This glue is, as may be imagined, very elastic. himself had used was that known as "D. H. Isinglass is a very strong glue, made from K.," and he had had no difficulty in making it skins, sounds, &c., of fishes; it is very adhere to glass-a point which caused some liable to be spoiled in making by overheat- surprise. ing. The pastes are all made from starch in some of its forms. Gluten is also used for a paste, but starch is the best. All additions of resin, &c., commonly recommended, are a damage to paste. Dextrine, or “British gum,” is of immense value in the arts as a cement. It is derived from starch by roasting or by the action of nitric acid. It was discovered by accidental overheating of starch, and its process of manufacture was for a long time kept secret. Its chief use for a long time was in the cotton manufacture. It is the standard gum for postage stamps, though it is said that gumarabic and cheaper substitutes are used in this country. No cement can be fire-proof which contains organic matter, since this is decomposed at a temperature about that of melting lead, or, say, 600° F. Cements containing oils will not be fire proof. Silicate of soda, mixed with asbestos, is the nearest to a fire-proof cement. It will stand a low, red heat. It is decomposed at a bright red. Water proof glues are made in two ways. Glue and linseed oil are recommended, but I have had better success with the mixture. The chromates may be used with glue. These, when exposed to the light, render the compound insoluble. Aquarium cement is the best water-proof cement I know. The formula is : NGINEER'S CLUB OF PHILADELPHIA, ΕΝ APRIL 2, 1881.-Dr. H. M. Chance described an attempt to extinguish the Kehley Run Colliery fire at Shenandoah City, by carbonic acid gas and nitrogen. The gas was generated in an open brick furnace with reversed draught, and forced into the mine through four 3-inch pipes, by injectors supplied with steam at 60 lbs. pressure. Each pipe was supposed to supply 1,500 cubic feet per minute, or a total of 6,000 cubic feet per minute. The attempt was entirely unsuccessful, and Dr. Chance attributes its failure principally to the impossibility of making the mine airtight, but also considers that the gas was delivered at too high a temperature, and that it was possibly mixed with carbonic oxide. The method seems to be worthy of further trial at mines that can be made thoroughly airtight. Mr. P. H. Baermann described briefly the construction of the Cooperstown, N. Y., Water Works, and particularly the method of laying the supply pipe extending from the pump house up the Susquehanna River into Otsego Lake, a distance of 4,500 feet. The pipe was laid from a staging carried on 120 barrels, and lowered in 108 feet sections. Up to 9 feet in depth the joints were made with dry pine wedges, and above this with lead. The end of the pipe is provided with a copper strainer, which is in 38 feet of water and 10 feet above the bottom. A paper was also read by Dr. Chance on "Wear in Wire Ropes," showing that the cause of rapid wear is often due to the use of drums, sheaves and pulleys of insufficient size, and that a great saving might be effected by increasing their diameters; especially that of the small deflection and knuckle pulleys and sheaves. The actual wear averages 0.138 cents in slopes, and 0.053 cents in shafts, per ton, for each hundred feet of lift. What is technically known as marine glue A ENGINEERING NOTES DVICES from Vienna state that the preparstands almost by itself. Where it can be put atory operations having been finished, on hot is admirable. It is composed of India the work of boring the great tunnel through rubber and shellac, dissolved in naphtha. Some kinds are hard, some almost liquid. I have seen this glue adhere to glass so firmly as to tear the glass when plates were separated. In the discussion which followed, Dr. Parmalee gave some interesting experiences in the manufacture of marine glue. He said its melting point was about 230°, and in making it was injured if the heat was carried above this point. In applying it care should be taken not to go above this heat, as the melting point would be raised and the strength diminished. In applying it the soldering iron may be used, but its heat must be regulated. In answer to Dr. Parmalee, Dr. Phin said that Jeffries, the inventor, put three kinds of marine glue in the market; that the kind he the Arlberg has now actually commenced. This tunnel will be one of the longest in the world, though not so long as that of St. Gothard. So far the operations on the eastern side of the Arlberg have progressed very favorably. The rock there found is a micaceous slate, through which the contractors find it possible to advance at the rate of from three to four meters a day. On the western side, on the other hand, the advance of the tunnel is retarded, and the operations frequently disturbed by the repeated inrush of large quantities of water. The contractors were warned before commencing the work that this was only to be expected. The geologist further advised that the tunnel should be carried through a lower stratum of rocks, which are of denser material |