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218 table, or even on a "trial trip' with a special staff of engineers to collect them over a few hours, or perhaps days, but they are the averages of months and years of every day's work, which for cominercial purposes is the best guide, as representing what the shipowner has to pay for. The data available with the triple-expansion en- gines of the Port Augusta comprise seven consecutive voyages extending over three and a half years, using sat- urated steam, as well as the five fol- lowing voyages, after being fitted with superheat, extending over three years, all of which are from London to Adelaide via the Cape of Good Hope, most of them being without any call at an intermediate port. The reason that the outward voyages have been taken is, not only that they cov- er the same run, but also because the - same bunkers for the whole voyage were taken either on the Tyne or at Middlesbrough from the Auckland (Durham) or Mickley coal seams. The conditions, therefore, are exceptional, if not unique, for the purpose of com- parison. The data dealt with of the quadruple-expansion steamers Port Lincoln and Port Mac- quarie are on exactly the same basis as that of the Port Augusta, and cover three voyages of each steamer to Melbourne from London, calling at the Cape, with this difference, that two-thirds of the bunkers for the voy- age were Mickley coal (unscreened) and one-third Natal coal, which latter gives a higher percentage of loss (ashes, etc.), and consequent con- sumption, than the North Country coal. There 1s also. a.-deduction of two tons instead of one ton a day on account of these steamers carrying more than 600 emigrants, besides a crew of 125, or about 740 souls all told, entailing a heavy expenditure of coal for galley fires, bakers' ovens, and steam for the cooking-presses, boilers, pantry sinks, plate heaters, etc. The above results cover all the con- tingencies which arise on a long sea voyage--weather, adverse trade-winds, currents, also coal troubles arising from its being only "fair," or what is described as "dirty" or "small;" furth- er, the human element is included, a most important factor affecting voy- engines of the _ cated horsepower THE MARINE REVIEW age results. Therefore these data have a special value to the shipowner. The engineer naturally asks for a higher standard, by which to gage the capabilities and possibilities of the use of superheat; for this reason the re- sults of a selected voyage, from Lon- don to Cape Town, of one of the steamers fitted with quadruple en- gines is given when the coal was de- scribed as "good" but "small," the weather was "fair to good,' and the stokehold crowd well up to the aver- age. Then we get:-- ? _ Average of \ Selected.. 5 voyages. Days on passage...... 19 d. 10 hr. a d,17-hr; m, Speed 12.92 knots 12.77 knots Coal consumption per day for main engines and ~ Sighs Ga noe 50.33 tons _ 51 tons eee wesc we eee es oe auxiliaries Coal per [outle Pin 043 ES Re ele i es ea ee igs 4,500. 4,122. The part of the voyage from the Cape to Australia is generally more detrimental to exhibition results, ow- ing to weather conditions, as well as to the less satisfactory quality of Na- tal bunker 'coal taken -at the Cape, which consequently increases the daily consumption without any increase of indicated horsepower. From the re- sults obtained we get the following consumption: Lbs. per Lae PB, . per hr Triple-expansion, saturated ..... 1.6 Triple-expansion, , superheated..... 1.4 Quadruple-expansion, saturated... 1.34 Quadruple-expansion, superheated. Tnd5 "ine figures for quadruple engines with saturated steam are taken from similar data of two steamers fitted with engines of 3,000 indicated fA. P. during seven voyages each to Australia via the Cape, with the same bunkers as used for the superheated quadruple engines as far as the Cape already dealt with. In the following comparison of the economy obtained the consumption for quadruple engines superheated is taken at 1.15 lb. per hour per indi- obtained on the voyage as far as the Cape, because coal from the same collieries--name- ly, Auckland or Mickley--was burnt as was used on the other steamers. In the case of the voyage averages of the Port Lincoln and Port Macquarie, ECONOMY AND SAVING OF COAL IN TONS PER DAY PER 1,000 I. H* P. Saving, oe ed Ponds per tons per day ; Rear I, Ht P. per Economy, per 1,000 Uae stot su- ey Over triple expansion saturated fe ea ae see ' Abe wig ces PRPs slg els mee 44S vies 1.6 pepe ane) persion oe Over triple expansion saturated : set med Peles ' Bl NG ete ee ek 1 Quadruple expansion Over triple expansion saturated . oe ae superheated at ... 1.15 A ee 156 28.1 Sup crapie crpaaion fee Cree pls expansion. : super- whe tee ; CAUGG alae ck Quadruple expansion Over quadruple "expansion sat- oe ie vis superheated at ... 1.15 urated at BoB let 0. 0 ROC 0 6 0 p00. 8 wb 6:9 1.34 14.2 2.03 June, 1914 the consumption works out at 1.29 Ib, per hour per indicated horsepower in consequence of one-third of the coal being from Natal, giving a higher percentage of loss. These results are shown on the dia- gram up to 10,000 indicated horsepower. The additional cost of fitting su- perheat cannot be set down at any definite figure, as although a large number of installations have been ft- ted, the different conditions that have to be complied with make a compari- son, in order to form a standard of price, very conflicting; still, for rough estimating, it may be taken as rang- ing from 15s to 20s per indicated horsepower, against which the re- duced size and consequent cost of the boilers must be considered. The full benefit of superheat can only be obtained by extending its use ta all the auxiliaries; 'and this tas been carried out on the vessels fitted when new. The steam pipes are of steel and the gland packings mostly metallic. The temperature used is about 500 degrees Fahr., and is regu- lated by a mixing valve from the sat- urated steam pipe line. This arrange- ment ensures dry steam to the auxil- iaries without any injury, although they are not all specially constructed tor the use of superheated steam. Most of the leading makers of auxiliary engines make the necessary alteration for moderate superheat with but little, if any, extra charge. The mixing of superheated steam with the saturated supply for the winches is also a great advantage, even though very little su- perheat, if any, gets so far. The use of superheat on turbines is another and most interesting phase of the subject, and one on which a resume of experience would be most valuable whether on the turbine direct or after passing through the recipro- cating engine. The data on the use of superheated steam during the last three years con- tained in this paper has been collected by the writer's firm in their profes- sional capacity of consulting engineers to the owners of the steamers. The fact that superheat has been fitted in all their subsequent vessels built, after a careful comparison as judged from the owners' standard of coals paid for, prompted the writer to place this in- formation before the members of the Institution as pointing to the facts:-- 1. The economy of coal claimed is maintained. "2. 'The economy with triple-expan- sion engines of 2,000 indicated H. P. after being altered to use superheat has been 12.14 per cent. 3. The economy with quadruple- Die ea eR eg