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June, 1914 advocating the use of superheat; if such were the case, however, the records of the past 70 years alone are full of instances of the devices. brought out for steam-jacketing, reheating and other ar- rangements for retaining and maintain- ing the temperature in the cylinders. The drop in the temperature, not only between the boilers, and the engines but also in the cylinders themselves, beyond that due to the expansion of steam, has - been, if not the greatest, at least one important -cause of loss of power in steam engines, as it has thereby in- creased the amount of saturation. in the steam. Another loss arose from the amount of saturation brought over by the steam from the boilers, when priming was not violently taking place. This loss is seen more or less in all marine engines by the quantity of water which comes down through the pis- ton-rod glands, to the detriment of the packing and the piston-rods. It is also manifest by the noise which betrays the presence of water in the cylinders, although there may be none of the usual evidence of priming in the boilers, which shows that whilst -a small percentage might be attributed to condensation in the cylinders, a large volume is really due to the heavy state of saturation of the steam coming from the boilers, and, moreover, that this is a variable quantity, due, no doubt, to the conditions of firing, circulation, or the quality of fuel. Water From Cylinders In order to obtain some data bearing upon this loss, measurements were taken of the water coming from the cylinders of quadruple expansion engines of 3,000 indicated horsepower working under saturated steam conditions, readings being taken during the voyage, and at times it was found that as much as 20 gallons per hour was drained off the M. P. 2 and L. P. steam chests. The fact that such a quantity of water was found to accumulate in the cyl- inders of a quadruple-expansion en- gine, working under saturated-steam conditions, convinced Alex. J. Dud- geon and the writer that super- heat would convert this loss into effective horsepower and so contribute to a more economical result. The mod- etn system of superheating steam passes the saturated steam from the boiler through small tubes placed in different Positions, according to the type of boiler, whether water-tube or marine cylindrical multitubular, usually termed the "Scotch" boiler. Some of these systems have been placed before the members of the institution in papers Tead by Professor W. H. Watkinson, on "Some New Types of Superheaters", periodically, THE MARINE REVIEW in 1903;:by: Felix > Godard, in "Notes on the Use of Superheated Steam with Marine Engines", in 1908; by Mr. Yarrow, on "Results of Experi- menting with Water-Tube Boilers with Special Reference to Superheating", in 1910; andalso before the Institute of Marine Engineers by Mr. White, on "Marine Engines under Superheated Steam', in 1910. Design of Superheaters It is not proposed to deal with the various points of interest regarding the different types or design of super-heat- ers which naturally arise, but which do not come within the scope of this paper, which is confined to the experience of the use of superheat on steamers, with special reference to the important ques- tion of economy and cost of upkeep, based on over three years' working in engines of both triple and quadruple expansion type in the mercantile marine engaged. in a regular trade, voyage after voyage, to Australia via the Cape of Good Hope. In the system adopted (Schmidt's) the steam from the boilers passes into a vertical pipe called the "saturated" header placed in the smoke- box, from which small branch pipes are led horizontally across the front of the tube plates, the pipes passing down each tube of the row being doubled in a U form for that purpose,, so that each "element", as it is termed, is a series of U's, the other end being brought back to what is termed the "superheated" header. The jointing of each end of the element to the headers is effected by a small cross bar or "dog" with a stud through the center, so that each dog makes two joints. Careful supervision, testing and tightening up, as the pressure rises when getting up steam, prevents any leakages after- wards, as when once tight the fittings do not give trouble. A drain is fitted to both headers, that on the saturated header for blowing away any scum that might be brought over from the boiler, and which would possibly choke the lower rows of elements, and a drain on the superheated head- er to permit of a circulation of steam through the elements when getting up steam, or when the steam is not being circulated in consequence of the sup- ply to the engines being shut off whilst working the engines to orders The elements are examined being removed from each nest of tubes in rotation, so, many each voyage; thus all are dealt with at least once a year; but whenever the boilers are cleaned the ends of in ports. 'the elements are examined from the combustion-chamber, as they are only k tube- about 9 in. inside from the bac 215 plates, for any signs of leakage at the weld of the U bend of the elements. These defects are something less than 0.1 per cent, and are generally only pin-holes. Even should it be neces- sary to deal with the U end it is not a serious matter, either in time or expense, and, in the event of a serious leak, the steam from the boiler can be shut off the superheater and by- passed direct to the engines, whilst the defective element is withdrawn and the joints on the headers re- made with blank plugs, the gross area through the elements allowing for a considerable reduction without unduly wire-drawing the superheated steam. Experience has shown no _ deteriora- tion of the elements from corrosion or burning of the end, or any inju- rious action on the boiler tubes. The chief expense incurred with superheat is on account of .extra labor when withdrawing these elements for in- spection. None of the steamers un- der consideration has been delayed either in port or on the voyage from defects in superheater elements since being fitted, notwithstanding the fact that they are turned round quickly and have long runs, that of the Port Augusta being 45 days without a call at any port, and the Port Lincoln and Port Macquarie 39 days, with a call of a few hours only at Cape Town for coal and fresh water. The clean- ing of the tubes on the voyage is ef- fected by "Diamond Blowers" fitted in each combustion chamber, and they are blown through every day, the op- eration taking about two or three minutes for each nest, the soot which accumulates in the smoke-box being cleared away through the doors pro- vided for the purpose. These blowers can be fitted to double-ended as well as single-ended boilers. Internal Lubrication The absence of moisture, upon which marine engines rely for internal lubrication, makes the lubrication of the cylinders and valve faces of most vital importance when superheated steam is used. In the first instance, an excess of internal lubrication is advisable, until the pores of the metal surfaces become saturated and filled up with oil. When this has taken place it will be found that, although the surface of the cylinder walls may be cleaned and wiped when they are hot, upon the metal cooling down a film of oil will be squeezed out of the pores on to the surface of the metal. When this condition has been attained, the quantity of oil for in- ternal lubrication may be reduced with safety. as On the Port Augusta, of 2,000 indi-