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6 Oa MARINE REVIEW. Engineering Subjects. CONDUCTED BY GEO. C. SHEPARD. ECONOMICAL PROPULSION. An absorbing and vexatious problem among the vessel owners and man- agers in these times of low freights is the reduction of operating expenses,and a method by means of which the coal bill could be reduced would be hailed with delight. It is hardly possible with the well-designed expansive engines and efficient boilers now in general use here to make any alterations or ad- ditions that would affect the coal consumed, and it has probably occurred to most people interested in steamboats that there is a speed for every boat and every draft of that boat at which the coal consumed per mile is the least that will carry that boat a mile. In short, commercial economy demands that the vessel should proceed at such a rate as to make each mile cost as little as pos- sible. The most conclusive method of arriving at this speed is t» try the ves- sel at all desirable speeds. 'he expense in time, labor and money is pro- hibitive against making speed trials when the vessel first comes out, but it is determined approximately and perhaps closely by many by observing the cost of the different speeds the vessel makes in her ordinary trips. There is, how- ever, a method of determining this by calculation, if the proper data is at hand, and we have before us the data obtained from two vessels to illustrate. Now the power to drive a vessel varies with the cube of the speed and approximately with the cube of revolutions producing that speed, and since the ratio between the speed of ship and the revolutions per minute varies greatly with the weather, we will make the revolutions the basis of our calcu- lations. Whether a vessel proceeds fast or slow itis agreed that a certain quantity of coal is necessary to supply steam for the auxilliary engines and pumps, to maintain temperatures of boilers, pipes and cylinders and to over- come the initial friction of the engine, and this will be (q) pounds per 24 hours. 'To this must be added the real cost of prorulsion, which at the rate of one revolution per minute -- k lbs. and at R revolutions per minute -- kR8 Ibs. per 24 hours; then the total coal per day Q = (q+k R® ). Now having data from which we can find two values of Q corresponding to two rates of revolution, we easily derive, from k--[ =o and q=k R38 the values of (k) and (q), and substituting them in the formula Pa aia) ae proposed by Mr. Lowe, U.S. N., we find a value S which is the most econom- ical rate possible, In vessel [A]. R=72.7. R=724 Rev. per min. -- Q=63,194 lbs. Q==42,552 lbs. ' k--.146 lbs. q==7,094-lbs. 62.4 Rev. per min. In vessel [B]. ; -- R=71. R=67 Rev. per min. Q=58,272 lbs. Q--564,072 lbs. k=.078 Ibs. q==31,071 Ibs. S--59.7 Rev. per min. In vessel A the economical rate and the lowest rate observed happen to be the same, and in both cases the economical rate is lower than usual rate of or- dinary operation. It may, however, be desirable to take into considerarion the other constant expenses of maintenance and operation in the determination of this economi- cal rate, and this can be done by substituting for the quantities (q) and (k) their costs in dollars and cents and adding to the value thus found of (q) the cost per day of such other constant expenses as may be desired to take into this determination, and substituting these values in the equasion, s--(") 4. . ~ Now in vessel [A] the sum of those expenses which do not vary with the speed of the vessel, including interest, taxes and depreciation, will approxi- mate $275 a day, and this sum will raise the economical rate to a point higher than it is practicable to maintain, and it remains for a vessel owner to deter- mine what expenses shall be taken into consideration in this method. Then. there isa way of determining the valaes of [q] ank [k] of a vessel from the data of one rate of coal consumption and corresponding revolutions, but more of this next time. THE JOY VALVE GEAR. In aconversation witha prominent engineer on the lakes we were asked our opinion concerning the Joy valve gear. A favorable reply elicited an un- favorable one from the engineer, and his reasons were that in the Joy valve gear there were no opportunities for changing the lead without cutting and mutilating somewhere, and also that the constant lead would not permit of high rotative speeds, such as are developed at times on the cruisers of the navy, un- less the lead was made large, in which cause it would be too much for lower speeds generally used. Regarding the changing of the lead, the gentleman's opinion isagood one, but the opportunities for changing are as good with a Joy valve gear as with the Stephenson link gear in which the go ahead and backing eccentrics\are cast together, as is the case on too many of our large en- gines. Supposing the engines on the cruisers are designed for economy at low speeds and their valves have leads corresponding ; now, using the Stephenson link this lead is diminished when the engine cuts off longer, as is necessary for higher speeds than the economical, while with the Joy gear the lead is the . same at long or short cut-off, and would be greater at a long cut-off than with the Stephenson gear, supposing both have the same lead at economical speed. Marine Review.--A horizontal pump has been working against a boiler pressure of 150 pounds for ten years and doing its work well, but will not work against atmospheric pressure through a hose. Water valves are all right; steam valves are all right. What is the matter with the pump? Cleveland, O., March 9, 1894. At first sight this question seems analagous to the one "'Why is the moon made of green cheese?" or 'Why does the Keeley motor mote?' ,but on further consideration we can conceive that the water valves are all right to a visual inspection, but that due to weak springs or light weight they require the back pressure of 150 pounds to seat, and that the lesser pressure of the atmosphere plus the friction of the water in the hose is not sufficient to close them quickly enough. We would be pleased to hear from engineers on this subject, as to whether they have experienced this difficulty and what examination proved the cause to be. QUERY. New Schedule of Wages. At a meeting of managers of the Lake Carriers' Association in Cleve- land, Tuesday, at which Secretary Keep and nearly all of the leading owners of Cleveland were in attendance, the salaries of officers and men in charge of the shipping offices were cut about 20 per cent., and the schedule of wages covering all employes on vessels was reduced material- ly from last season's opening card. It was decided to close the shipping: office at Escanaba and open a new office at South Chicago, the latter to be under the direction of the shipping master at Chicago. Messrs. John Duff and Andrew Hackett of Amherstburg were in attendance, and arrange- ments were made with them for continuing the range lights in the vicin- ity of the Lime-Kilns crossirg, which are on Canadian soil, and which, with the exception of the Point Edward ranges, are the only private lights now maintained by the vessel owners. No arrangements have as yet been made for maintenance of the Point Edward ranges. The new schedule of wages follows: SCHEDULE OF WAGES, LAKE CARRIERS' ASSOCIATION, OPENING OF SEASON, 1894. On Steamers-- PER MONTH. First class boats, chief engineer.............-..+6 va dtlaele tsa dyes $100 First class boats, second engineer..........:cscsseseeeeeseee seers 70 Second class boats, chief engineer....... sieve sdevucPonge ty Ne $75 to 90 Second class boats, second EMgineer.......seeeseereeeeseesesens 60 Third class boats, chief engineer..... ..-.........006- eyejewate 60 to 75 Third class boats, second engineer ...........:.sseeseeeeeneeeess 50 First mates...........sss00e+ Beige eee ee oral seis ee ec cae 50 to 70 Second mates,.........sesccccespoers Brcatese Tecan ens thas sestysatnenescse 35 to 50 Cooks......... eeaoees sa pleases ods be He Snbanboogor enoghae dg Rich ean on ar 35 to 50 FeIpers ....2..eeseeseseeesseceesee coseccescnsceecnsceesessesenscseerseeees 10 to 15 FUremMen.......scseeeesseeeeeee See ene egret eee Bina teow age? 25 to 30 Wheelsmen.............0+4 Beker abet ecb cots Vinat aaa Sonia Oca 25 to 30 HE OSC Gate aed se pee eate rine oe fetch oe tienes gales an Soper 20 to 30 WGC what Gees tracert cher pcdeea dgcss cards sntacencseasbanndie << <pdnaes 12 to I5 Oilers.;.:..: es ade Geeta mere soe cee oeearaie ee ce era 25 to 30 On Consorts and Sail-- SEGitsfrcpitEL cube Steger eledemseeeewaite cn aasjncas dale siapahe ee eden ager elacn anes 30 to 45 SE COMM tbat ese cereus dsinrins ais oihs rs ociuane,Seonside saiejeuccidav ace dee ede tee 25 to 35 Cooks.,,.........00 pee sees iat cic ss Care tae iG eae ee ar 25 to 30 SEAMEN Ne cesses cacneaenes Beceem eel cenes cote netee onan aetcneseee: 25 to 30 IES Osi Seerecteialeelniect eset istetoe(setectetia pele esis aaencteets eel clots cetera 12 to 15 Firemen fitting out will be paid $1 a day. Highest Speed Afloat. The highest speed afloat has once more been exceeded, the British torpedo boat destroyer Hornet at the present time standing ahead of all craft in regard to swiftness of steaming. The Hornet is a sister vessel to the Havock, the first of this new type of war vessel, of which the Brittish government is building about thirty. The Havock, which was illustrated and described in the REviIEw of Feb. 8, attained a mean speed on trial of 26.783 knots, and now the second boat, the Hornet, has made an average of 28.02 knots on six runs. These boats are 180 feet long, 18 feet 6 inches wide and are ofthe usual torpedo boat construction in general appearance. The Hornet, however, has no less than four funnels to serve her eight boilers, and in this respect differs essentially from her sister-ship. \ SOME TIME AGO THE MARINE REVIEW puBtisHED A SHORT HISTORY > OF LAKE NAVIGATION, RUNNING THROUGH FIVE NUMBERS. WE HAVE SEV- ERAL SETS OF COPIES OF THESE NUMBERS WHICH WE WILL FURNISH AT 80 CENTS. ONE OF THE NUMBERS CONTAINS INFORMATION OF LOCKS OF THE 81. LAWRENCE AND ERIE CANALS, WHICH IS WORTH THE PRICE ASKED FOR ALL OF THE NUMBERS,