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64° the latter the most important im- provement in boiler practice in 40 years. These factors will be referred to later and meantime to continue the economic comparison. The sav- ing in weight should be reflected in increased cargo dead weight but if we have to put that saving back into the bunkers in the form of coal what has become of the saving in the boiler room? For this offset more- over it appears that we have to pay at the rate of around $9000 per year. There are also other charges as will appear from Table III. The install- ’ ation in ship 8 represents in added first costs about 30 per cent more than in ship 1 and over $1000 per annum in interest charges. The foregoing is given for what it may be worth. The next point mentioned by Dr. Sadler is that of higher pressures which we will pass for the moment since it will present itself later in connection with types of engines. The next is superheat. There has been considerable noise made one MARINE REVIEW. cost possible. This, sooner or later, brings in the question of whether we shall sacrifice possibly 10 per cent in the cost of generating this heat in order to save 5 per cent in the using of it. Broadly stated that is the case in a few words. If the superheat can be obtained by utilizing otherwise waste heat well and good provided we really want it, but that condition does not exist in a well designed and operated in- stallation where the temperature of the uptake is frequently below that of even saturated steam. That ends the argument before it begins in so far as waste heat is concerned. Then comes the question of how far it is profitable to go in the direction of taking some of this heat, which we have either been transferring to the water or using to promote and _ control combustion by heating the draft air, and apply it to superheating our steam. There are two answers; one leads to a point where it is difficult to decide whether the boiler or the superheater comes first, like TABLE IV Condensed Trial Report, Ships S1 and S2, Table I Duration of trial, hours Coal per hour, pounds, all purposes Ash, per cent Moisture, per cent Combustible, per cent OCOBNA Tp ON B.t.u. Factor of evaporation Water per pound dry coal, pounds Dry coal per hour, pounds, all purposes Water to boilers per hour, pounds, all purposes Water per pound dry coal, pounds from and at 212 degrees... Efficiency on dry coal Indicated horsepower (I. H. P.)....s-s P. per hour, all purposes, pounds Water per I. H. Water per hour, auxiliaries, pounds Water per I. H. Auxiliaries, per cent of total Fan, per cent of total Steerer, per cent of total Air pressure at fan, inches of water Air pressure at ash pit, inches of water Air temperature at fan, degrees Fahr P. per hour, engine only Coal per I. H. P. per hour as fired, all- purposes Coal per I. H. P. per hour engine only Perrier Air temperature at ash pit, degrees Fahr. ...... Gas temperature at base of stack, degrees Fahr way and another at different times with regard to various specifics in an engineering way but of the various kinds of noises none has been quite so persistent as the super- heaters. If they only had their way one would have to wear asbestos clothing and smoked glasses around the ideal steam plant. . There are however some _ other things to be done aboard ship than to find out how much_ superheat can be packed into a pound of steam. The old advice to “first catch your hare” is very much to the point here. The first thing we have to do is to get our heat and every day necessity as well as common sense requires that we get it at the lowest the chicken and the egg, the other suggests examination and comparison of results. The foregoing is not to be understood as a denial of all ad- vantage from stperheating but only of the extent of the advantage claimed, keeping. in mind working conditions as they exist with multi-cylinder reciprocating engines. Where Superheat Is Effective It may be admitted that in simple engines such as locomotives and most auxiliaries, a gain, so far as actual steam consumption is concerned, may be derived from moderate superheat. We are not operating locomotives however and the tail, representing the auxiliaries, has not quite begun February, 1927 to wag the dog. The turbine is absolutely dependent upon superheat; in fact it might almost be said with- out exaggreation that the answer to the question “why is a.-turbine” is “to provide use for superheaters.” The reasons are simple and so well understood that it is not necessary to dwell upon them here;.. However because peppermint may be good for colic it does not follow that it is also good for chilblains. We are concerned with the matter of auxiliaries but superheat is not the answer as will appear in due time and with turbines we are hardly concerned at all. Reliable reports of actual _ tests of multi-cylinder reciprocating engines with and without superheat and in- cluding the boiler efficiency are so rare as to be curious. Many reports are avaliable showing engine steam consumption with and without super- heat and it may as well be said here that there are about as many on one side as the other, and among these are some which are so involved with the auxiliaries as to leave the answer in doubt. One report is found of such a test of a ship in the trade under consideration and showing an apparent economy of about 8% per cent in favor of superheated steam, and the results are of interest. First, the superheat was obtained frem absolutely waste heat, and the tem- perature of the stack even after passing the superheater was _ still greatly higher than it should be. Second, it is noted that the tests were not made under parallel condi- tions since in the superheat trials the ship was light and in the saturated trials she was loaded. Notwithstand- ing this, and everyone familiar with ships knows that there is a difference in revolutions between the two con- ditions, the main engines made higher revolutions and as much as_ 200 indicated horsepower more with sat- urated steam than with superheat at the same cut-offs and steam pres- sures. In order then to get the fig- ures for comparable horsepower the cut-offs were shortened and the rev- olutions fell off and in consequence the speed of the ship was reduced 0.7 miles per hour. This reduction in speed is equivalent to about 5 hours for the loaded trip, or in other words if the engine powers had not been reduced the running time would be about 5 hours less and accepting the stated consumptions as accurate the differ- ence would be about 17% tons, or about $88.00, or about $17.50 per hour for a 10,000-ton ship. Probably no operator will feel any degree of enthusiasm over this showing even if