for July, 1921 pound of water is equivalent to one B. t. u., which is not strictly true. Now the result obtained by Mr. Brooks is approximately correct, assuming the above conditions, but I do not think that the method he uses to get that result is right. As a consequence I am going to offer some solutions, using the right methods and obtaining approximate results, assuming the conditions to be as above stated. In my solution, let X = number of pounds of steam required; from the steam tables, one pound of steam at 6-lb. gauge pressure contains 1,152 B. t. u. One pound of water at a temperature of 200-deg. fahr. contains 169 B. t. u. Then to condense one pound of steam at 6-lb. gauge pressure to water at a temperature of 200deg. fahr. will give us 1,152 — 169 — 983 B. t. u. = = To heat the water from 40-deg. fahr. to 200-deg. fahr. requires 169 -8 161 B. t. u. The problem now becomes an equation or proportion. As an equation, the number of pounds of steam times the number of B. t. u. given up by one pound of steam the number of pounds of water times the number of B. t. u. required to heat one pound of water from 40-deg. fahr. to 200-deg. fahr. In the form of a formula this now becomes = of steam and 30,000 4,222 = 25,788 pounds of water, which is the same as the result obtained before. Under actual operating conditions, however, the moisture in the exhaust steam and condensation carried along with it must be taken into consideration. In large plants where the exhaust steam is also used for other purposes besides the heating of the feed-water, the percentage of moisture and condensation may be smaller or greater, depending upon the amounts so used; also oil drains may carry away a considerable amount, or traps may drain the lines. It is also affected by the condition in which the steam leaves the boiler-superheated, saturated or wet-as well as the manner in which the steam pipe lines are covered and their length, together with the character of the apparatus used. In this case, however, let us assume that the condensation and moisture in the steam is 10 per cent. Then the problem becomes And What Caused It. It Worked Fine During the Heating Season but When the Heating Load Dropped Off It Could be Heard for Blocks. In reading the article on the above subject in the March issue of the National Engineer by A. C. Waldron, it called to my mind a similar experience that might be of interest to the readers of the National Engineer. There were two closed heaters in this plant, and the exhaust connections and the two heaters were arranged as shown in the accompanying illustration. From this it will be noted that the exhaust pipe is 7-in. up to the point where the branches are taken off to the heating system, from To Exhaust Head Heater X X 1,144 = 4,830,000 X where X X (230169) 10 is the quantity of heat contained in the condensate and X 10 the amount of condensation. Solving we get X = 4,142-lb. of steam required, 414-lb. of condensation, and 30,000 (4,142 + 414) 25,444-lb. of make-up water. There are other factors affecting the final result, but my last problem is accurate enough for all practical purposes. If the amount of moisture and condensation can be determined at the point where the heater is installed the problem is practically solved. In the solution given by Mr. Brooks the re which it is reduced to 4-in. up through the back pressure valve, the second heater and up to the exhaust head. During the time when the heating system was in use no noise could be heard at the outlet of the exhaust head, but whenever the heating system was not in use, and particularly when the engine was carrying a heavy load with low boiler pressure, the noise could be heard for several blocks. It was quite evident that the trouble was due to the restricted area of the 4-in. section of the exhaust pipe, together with the small back-pressure valve and also small exhaust head. This in turn of course increased the back pressure on the engine and increased the steam consumption, with a consequent waste of fuel. To remedy the trouble I installed a new section of 6-in. pipe in place of the 4-in. section, together with a 6-in. back pressure valve and exhaust head. This eliminated the noise and at the same time greatly reduced the back pressure on the engine, providing more satisfactory and economical operation all around. I was told that the reason the 4-in. pipe was originally used was that when the engine was originally installed to replace a smaller unit the 4-in. pipe was already in place, together with the back-pressure valve and exhaust head, and to keep down the cost of the installation the 4-in. section was left in place from the point where the heating system connections were made. Evidently the man who was responsible for the installation failed to think of what this would mean in terms of coal, because in operating under these conditions for long periods during a number of years, the extra fuel burned to operate under this excessive back pressure would have paid for the extra cost of pipe and other apparatus several times over. This was another case of the penny wise and pound foolish idea. Milwaukee, Wis. H. A. Jahnke. drips from the packings, a combined settling tank and filter, and lastly a small single steam pump for pumping the oil back to the gravity pressure tank. I found that the oil was wast Oil Pump Exhaust for July, 1921 was screwed was taken off. A short distance toward the centre of the pump from the exhaust connection was found a hole about 3g-in. diameter from which the oil poured out until Separating Tank Filter Fig. 1. Showing Elevation of Oil System Pressure Tank the valve in the suction pipe was closed. Examination showed that the gasket between the exhaust and this hole was eaten away, also that this hole was a flaw in the casting which extended into the suction chamber. Thus the mystery was solved. The exhaust pipe turned down to the floor and discharged into a sewer. When the pump was not running the oil had been flowing from the filter through the suction pipe through the sand hole in the casting, through the hole in the gasket to the exhaust pipe and out to the sewer. Some iron cement and a new gasket cured the trouble. Since that time one barrel of oil a year is all that I use. An elevation of this oil system is shown in Fig 1. A sketch of the pump is given in Fig. 2. for July, 1921 NATIONAL EDUCATIONAL COMMITTEE NATIONAL Any slide valve engine requires long steam ports and this means that a large amount of surface is exposed to the steam. The slide valve engine is also at fault on account of the fact that the same ports are used to conduct the live steam to the cylinder and to remove the cooled exhaust steam from the cylinder. The four-valve engines overcome these objections. The Corliss Engine.-One of the oldest and best types of four-valve engines is the Corliss engine, which utilizes a trip gear mechanism. The cylinder of the Corliss engine has four the valve stems; they are connected the steam hooks. The exhaust valve W. When the engine is in operation the wrist plate W is given an oscillating motion by the eccentric to which it is connected through the rod A. This causes the bellcrank lever D to 346 cut-off by controlling through the rod. H the position of the knock-off cam on the crank lever D. The valve gear in some Corliss engines is operated by a single eccentric while in other cases two eccentrics are used. The Corliss valve gear with one eccentric cuts off the steam at less than one-half of the engine stroke. With two eccentrics, one to control the admission valves and the other to operate the exhaust valve, a greater range of cut-off can be had. Engines of the Corliss type are very economical, but on account of the trip mechanism must operate at relatively low speeds, usually about 100 revolutions per minute. Setting Corliss Valves.-The Corliss engine valve gear usually has well marked points to show the extreme travel as well as the central position of the wrist plate. There are also marks showing the travel of the working edges of the valves. -Double Grm -Knock off Cam Sever Safety Cam Fig. 1. Showing Valve Gear of Corliss Type of Steam Engine. valves. Two of these valves control the entering steam to the cylinder, while the other two control the exhaust steam from the engine cylinder. The cylinder of a Corliss engine is illustrated in Figs. 1 and 2. The valves of the Corliss engine are cylindrical in form and are located in chambers S and E at the top and bottom of the cylinder and at the extreme ends of the stroke of the engine. Referring to the steam valves, the bell crank levers D work loosely on To set a Corliss valve, remove the valve bonnets, place the wrist-plate in its central position and fasten it in oscillate upward and downward about this position by placing a piece of the spindle J as an axis. The steam paper between it and the washer hooks engage the main valve arms M which holds the wrist-plate on the upon their extreme downward move- stud. Now with the steam valves ment. The upward movement of the hooked up, adjust the rods R leading hooks lifts the lever M and opens the from the wrist plate to the double arm valve. The valve continues to open lever so that each steam valve will until the hook is disengaged by com- have equal laps. The amount of this ing in contact with the knock-off cam lap varies from 1/16 to 3 in., dependon the crank lever D. As soon as the ing on the size of the engine. Also valve is thus released it is returned to adjust the exhaust valves with zero its normal position by the aid of a lap. After the steam and exhaust vacuum created in the dashpot. valves have been adjusted the wrist The governor regulates the point of plate can be unfastened by removing Steam Hook -Knockoff Cam 397 the paper between the wrist plate and washer. The rocker arm with the eccentric rod attached should now be placed in vertical position by means of a plumb line. The eccentric rod must now be adjusted so that the rocker swings equal distances on each side of the plumb line. The hook rod can now be connected to the wrist plate and the adjustments made so that both the rocker arm and wrist plate are plumb when the eccentric is vertical. To secure the proper point of cutoff, the governor is fastened at its highest position, the wrist plate is disconnected from the eccentric and the governor cam rods are adjusted so that the releasing of the steam valves by the knock-off cam occurs when the port is open about 1 in. When the governor is in its lowest position the releasing gear should not detach the steam valves. To adjust the lead the engine should be placed on one of its dead centers and the eccentric should be turned loosely on the shaft in the direction in which the engine rotates until the proper lead is secured. After the valve is properly set the valve bonnets are replaced and all adjustments are carefully made so that the hooks engage properly and the dashpot rods are of the proper lengths. QUESTIONS 1. What are the advantages and disadvantages of the Corliss valve gear as compared with the balanced slide valve? 2. Reproduce an indicator diagram for a Corliss engine and mark the points of admission, cut-off, release, and compression. 3. Explain in detail how you would start an engine equipped with a Corliss valve gear. 4. Are four-valve engines built utilizing four valves similar to the Corliss valve gear, but without the releasing mechanism? If so, describe the construction of this type of engine. 5. Under what conditions is the double eccentric Corliss engine preferable to single eccentric gear? JULY INVENTORS JULY INVENTORS William J. M. Rankine, Author of By ROYAL H. HOLBROOK The first half of the year 1921 has now passed and we are entering upon the last half as a mariner doubtless does upon an uncharted sea but with our hearts all beating regular and our heads clear for thinking we will come out all right, I am sure. The first day in this month that at- most of us. On the fifth occurs the manners Z, fortune (this last is essential), Then L is a function of x, y, z, "Now integrate L with respect to d t to see, The definite integral marriage must A very concise demonstration." The famous Jacquard loom was in- largely due to Frank J. Sprague, for July, 1921 building elements is due to Eben M. Horsford, whose birthday is on the 28th, and on the last day of the month we Americans can well afford to tarry for at least a moment and pay respect to a Swede born gentleman, who actually through his Monitor saved the North on that memorable day in March, 1862, when it met the Merrimac in Hampton Roads. Ericsson was a great man and inventor. He was a master in the theory of mechanics and could and did apply all of his knowledge along these lines to actual machines. Pumping engines, surface condensers, induced draft, weighing machines, file-cutting machines, improved gun locks, sounding apparatus, all claimed his attention. In the famous locomotive contest at Liverpool, in 1829, he was present with his "Novelty," for this type of an engine was not strange to him, for in the two years previous he had developed a fire engine; had actually created a draft by the use of bellows and had made a boiler with twenty copper tubes and an internal furnace. He was already at this time associated with a well known Englishman, Braithwaite, in making machinery of many kinds. When the advertisement appeared in the papers of that day for a locomotive that could be operated on a railroad of a gauge 4 feet 82 inches capable of drawing a gross weight of 20 tons at a speed of at least ten miles an hour and consuming its own smoke (and the locomotive not exceeding a weight of six tons for itself), Ericsson immediately went to work for the prize, for it was evident that there would be several entering the contest. The "Novelty" was built to win, but on account of its light weight did not last through the complete test, but be it said to its credit it actually made a mile in fifty-six seconds while the speed of the train was nearer to thirty miles than the ten miles required in the contest. This contest over and the prize not won, this inventor turned his attention to the development of a caloric or hot air engine, and later to the screw propeller, the last invention being largely responsible for his removal to New York in November of 1839. Here he was associated with men of science and renown and when the lowering clouds of war were all about us as a nation he succeeded in securing the attention of President Lincoln and Secretary of Better white bread full of body the Navy Wells, regarding his style for July, 1921 FREQUENCY PROBLEM IN STEEL INDUSTRY of a warship, and on September 13, FREQUENCY PROBLEM IN STEEL IN- ice was at relatively low speeds with advisability of the generation of their where W = pounds of steam gener- ated per hour. There were then only two frequen- Much of the heavier steel mill serv- THERMOSTATIC METAL. . Thermos- 348 When these strips are heated the LIQUID SLIP REGULATOR . . Peak ENGINE FOUNDATIONS . . Founda- Fifteen or twenty years ago it was |