.t:LF= EDUCATOR 
 
Class 
 
 Book 
 
 Gop>TightN^. 
 
 COPYRIGHT DEPOSIIi 
 
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SELF-EDUCATOR 
 
 MARINE AND STATIONARY 
 ENGINEERS CATECHISM 
 
 . a , 
 
 PHILADELPHIA 
 1915 
 

 Copyright, 1915, by 
 WILLIAM C. WILSON 
 
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 ^ 
 
 ,-\^ 
 
 ? 
 
 /-^ ^ 
 
 JUL 3 1915 
 
 ^CU406582 
 
SELFEDUCATOR. 
 
 Rules to Find the Diameter, Circumference 
 
 AND THE x\rEA OF A CiRCLE 
 
 Q. Multiply the square of the diameter by the 
 decimal .7854 will give the area. 
 
 Q. How do you square the diameter? 
 
 A. Any diameter multiplied by itself equals 
 the diameter squared. For instance, 10 squared 
 equals 100. 
 
 Q. Why do you multiply by .7854? 
 
 A. Square the diameter and we get the square 
 inches in the square; if we multiply by .7854 we get 
 the square inches in the circle, the circle being that 
 fraction of the square. 
 
 Q. What do you mean by the word area? 
 
 A. By the area we mean the amount of surface 
 exposed to the action of the steam. 
 
 Diameter X by 3.1416 is the circumference of a 
 circle. 
 
 Diameter X by .8862 is the side of an equal 
 square. 
 
 Diameter X by .7071 is the side of an inscribed 
 square. 
 
 Diameter X by .7854 is the area of a circle. 
 
 Radius X by 6.28318 is the circumference. 
 
 Circumference -^ 3.1416 is the diameter. 
 
 The area of a circle -r- by .7854 and extract the 
 square root will give the diameter of a circle. 
 
4 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Miscellaneous 
 
 A United States gallon contains 231 cubic inches. 
 
 A United States standard gallon weighs nearly 
 8.355 lbs. 
 
 A cubic foot of fresh water weighs 62.5 pounds. 
 
 A cubic foot of sea water weighs 64 pounds. 
 
 35 cubic feet of sea water weigh one ton. 
 
 32 cubic feet of fresh water weigh one ton, and 
 weigh 62.5 pounds to a cubic foot. 
 
 2240 pounds weigh one ton. 
 
 A cubic foot of coal weighs 56 pounds. 
 
 5280 feet make one land mile. 
 
 6080 feet make one nautical mile. 
 
 1728 cubic inches make one cubic foot. 
 
 27 cubic feet is one cubic yard. 
 
 144 square inches in one square foot. 
 
 6 feet is one fathom. 
 
 360 degrees is the circumference of a circle. 
 
 7.48 gallons are in a cubic foot. 
 
 To get the circumference use 3.1416. 
 
 1760 yards is one mile. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 5 
 
 To Reduce. A Vulgar Fraction to a Decimal 
 Fraction 
 
 Divide the numerator of the fraction by the 
 denominator, adding ciphers to the numerator 
 until it works out in four figures. 
 
 Example: Reduce | to a decimal. 
 
 8)7.0000 (.8750 decimal | 
 64 
 
 60 
 56 
 
 40 
 40 
 
 Again: Reduce | to a decimal. 
 
 8)3. 0000 (.3750 decimal of 
 24 
 
 60 
 56 
 
 40 
 40 
 
 Again: Reduce f to a decimal. 
 
 8)5.0000(.6250 decimal of f 
 
 Again: Reduce j^ to a decimal. 
 
 16)5.0000(.3125 decimal of ^ 
 
 48 
 
 20 
 16 
 
 40 
 32 
 
 80 
 80 
 
6 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Cube Root 
 
 When a number is multiplied by itself twice it is 
 called the cube of the number, as the cube of 4 is 
 64, because 4X4 = 16 and 16 X 4 = 64, or 4 X 4 X 
 4 = 64. The cube root of a number is the number 
 the cube of which equals the number. The sign over 
 a number expresses the cube of the number. Thus 
 53 denotes the cube of 5, = 5 X 5 = 25 X 5 = 125 
 or 5 X 5 X 5 = 125 thus ^125 = 5. 
 
 Proportions 
 
 Engineers should be thorough masters of the prin- 
 ciples of proportion, as nearly all questions of 
 consumption and speed can be solved by it quicker 
 than by any other rules. In proportions, if the an- 
 swer is to be greater, make the second term the 
 greater. As you will notice in the following example, 
 the answer was greater because 12 men could earn 
 more than 5 men, and if it is to be smaller or less, 
 make it the second term. Always let this be your 
 guide, for if the answer is to be smaller, make the 
 second term the smaller, and if it is to be larger,, 
 make the second term the larger. , 
 
MARINE AND STATIONARY ENGINEERS CATErillSM 7 
 
 Example 
 
 men 
 
 5:12: :30 12 
 
 30 
 
 5)360(72 answer 
 35 
 
 10 
 10 
 
 If it takes 8 hours to walk 25 miles, how long will 
 it take to walk 60 miles at the same gait. The 
 answer in this problem is to be greater, so GO miles 
 will be the second term. 
 
 25:60:: 8 hours 60 miles 
 
 -. 8 
 
 25)480.0(19.2 
 25 
 
 230 
 225 
 
 50 
 50 
 
 If the repairs to an engine take 9 men 18 days 
 
 to do a job, how long will 16 men take to do it. 
 
 The answer is to be smaller, as 16 men will do the 
 
 work in less time, so we make 9 men the second term : 
 
 16:9: : 18 = 10 days. 
 
 18 
 9 
 
 16)162(10 days 
 16 
 
8 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Square Root 
 
 When a number is multiplied by itself it is said 
 to be squared, and is called the square of the number. 
 As 8 X 8 = 64 is the square of 8, the square root 
 of any number is the number whose square is equal 
 to the number given. The square root of any 
 number up to one hundred may easily be found 
 without working out, as the square root of 36 is 
 6 because 6 X 6 = 36 again ^^81 = 9; ^^100 = 10. 
 To get the square root of a large number, proceed 
 as follows: write down the number that the square 
 root has to be extracted from. Mark two figures, 
 counting from the right to the left in whole numbers, 
 and from the decimal point to the right point off 
 every two figures to the left. To get the square root 
 of 622521: 
 
 62|25121(789 answer 
 
 49 Get the square root of 
 
 148)1325 31|83|00(5.64 answer 
 
 1184 25 
 
 1569)14121 106)683 
 
 14121 636 
 
 1124)4700 
 4496 
 
 Get the square root 1 144(12 answer 
 1 
 
 22)044 
 44 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 9 
 
 Practical Questions 
 
 Q. What type of boilers are mostly used for marine 
 work? 
 
 A. The Scotch boiler on land vessels and tugs. 
 
 Q. What boilers are mostly used on land? 
 
 A. The return tubular boiler set in brickwork. 
 
 Q. Name the important parts to be looked after 
 on a boiler. Leaving out for the present the ques- 
 tion of whether the boiler was properly designed 
 originally. 
 
 A. The exterior of the boiler should be examined 
 for corrosion, expecially at the fire line and around 
 the ash pits if it is surrounded by water space. The 
 surface exposed to the fire should be examined for 
 blisters, and if any appear they should be cut with 
 a chisel so that their depth and extent should be 
 known. 
 
 Q. Have you noticed any scale on flues or crown 
 sheets? If you did how would you remove it? 
 
 A. By using compound. 
 
 Q. How is the pitch or the distance found between 
 the rivet holes in a boiler plate? 
 
 A. Divide the area of the hole by the thickness 
 of the plate and add the diameter of one hole. 
 
 Q. What is the effect of using steam expansively? 
 
 A. Its effect is in the economy due to the use of 
 the expanding of steam below the boiler pressure. 
 
 Q. What is meant by sensible heat and latent 
 heat? 
 
10 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 A. Sensible heat is that required to raise the tem- 
 perature of water from freezing point to the tempera- 
 ture of steam. Latent heat is that required to evap- 
 orate the water at the given temperature or the 
 heat which disappears in effecting the converting 
 of water into vapor. 
 
 Q. Have you noticed any bulging in the fire-box 
 plates? If you found a thin place in your boiler 
 what would you do? 
 
 A. Put a patch on it. 
 
 Q. Would you put a patch on the outside? 
 
 A. No; put it on the inside. 
 
 Q. Why so? 
 
 A. Because the action that has weakened the 
 plate will then act on the patch, and when this is 
 worn it can be replaced; but the plate remains 
 as we found it if the patch were put on the outside. 
 The action would still be on the patch, which would 
 in time be worn through, then the pressure of steam 
 would force the water between the plate and the 
 patch, and so corrode it, and during an extra pressure 
 the patch might blow off. 
 
 Q. If you found several thin plates what would 
 you do? 
 
 A. Patch each one and reduce the steam pressure. 
 
 Q. If you found a blistered plate what would you 
 do? 
 
 A. Put a patch on the fire side of the boiler. 
 
 Q. If you found a plate at the bottom buckled? 
 
 A. Put a stay through the centre of the buckle. 
 
 Q. If you found several buckles? 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 11 
 
 A. Stay each one and reduce the steam pressure. 
 
 Q. If the crown of a furnace were down, what 
 then? 
 
 A. Jack it up or put a bolt through the middle 
 and a dog across the top if the furnace were dowm. 
 Lengthwise, put a series of bolts and dogs. 
 
 Q. If you had a crack, what would you do? 
 
 A. Drill a hole at each end of the crack, calk the 
 crack or put a patch over it. 
 
 Q. If the water in the boiler is allowed to get too 
 low what may be the consequence? 
 
 A. Burn the top of the combusting chamber and 
 the tubes, and perhaps cause an explosion. 
 
 Q. If the water were to get too high in the boiler 
 what then? 
 
 A. It would cause priming and maybe cause the 
 cylinder head to break. 
 
 Q. What would you do in case the boiler was to 
 foam and carry the water over in the engine? 
 
 A. Open my surface flow^ and slow dow^n my 
 engine. 
 
 Q. How would you line up an engine? 
 
 A. Remove all parts except the cylinder and 
 crank shaft, strike a line from the top of the cylinder 
 head to the bottom of the crank pit, put the engine 
 on top centre, take the centre of the crank pin, take 
 the centre of the top of the cylinder, the centre of the 
 bottom of the stuffing box, then put the engine 
 on the bottom centre, and if you find it comes the 
 same your engine is in line. Then line your 
 guides. 
 
12 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Q. Where is most pressure on a flat-bottom boiler? 
 
 A. On the bottom with the steam pressure and 
 weight of the water. 
 
 Q. What is the difference between a high-pressure 
 engine and a low-pressure engine? 
 
 A. The high-pressure engine exhausts against 
 15 pounds of the atmospheric pressure while the 
 low-pressure engine exhausts in a condenser with an 
 air pump attached which relieves that pressure. 
 
 Q. What is vacuum? 
 
 A. It is a space avoided of all pressure. 
 
 Q. How would you place the cams on a shaft? 
 
 A. Ninety degrees ahead of the crank or J diameter. 
 
 Q. How would you set cut-off valves? 
 
 A. Place the engine on the top centre, place the 
 valves on the cut-off stem, run the valves up until 
 they cover the top and bottom port, then the valve 
 is square; then pry the engine down to where you 
 want to cut-off, run your cut-off valves up until 
 they cover the ports, and so on to balance the 
 stroke. 
 
 Q. How would you set main valve of an engine? 
 
 A. Place the engine on the top centre, put the 
 links in the head motion, give the valve the proper 
 lead, then reverse the links in the backing motion 
 on the same centre, and if the lead is the same, the 
 valve is square; place the engine on the bottom 
 centre and do the same and the valve is set. 
 
 Q. How far is the bottom gauge cock above the 
 crown sheet or tubes in the boiler? 
 
 A. From four to five inches. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 13 
 
 Q. How do you determine the tensile strength 
 of a boiler? 
 
 A. Tensile strength of a boiler plate means the 
 resistance which a piece of metal offers to being 
 torn asunder in the direction of the line of fiber; 
 for instance, when we say that a certain boiler 
 plate has tensile strength of 50,000 pounds we mean 
 that it takes 50,000 pounds of force or weight to 
 tear asunder, or entirely separate, a piece of metal 
 just one inch square of section. There are certain 
 methods by which tensile strength and ductility 
 are found, and, furthermore, there are certain 
 methods which each bear toward the other, which 
 is important for engineers to know. Let us look 
 into this for a few moments. In regard to deter- 
 mining the tensile strength of a strip of the plate 
 cut from a boiler to be tested, it is cut off to a certain 
 length and width, and is governed by the thickness 
 of the plate. It is not the intention here to go into 
 minor details. In determining the tensile strength 
 the strip is carefully measured in all directions and 
 the result noted after it is placed in a testing machine 
 and subjected to a force sufficient to break asunder, 
 such force being recorded by the machine ; then the 
 calculations are made in the following manner. 
 Let us assume that we have a test piece which at 
 the point where the fracture is to take place, is ^ 
 inch wide and J inch thick. Now to find the area, 
 as per requirements of the foregoing rule, we must 
 multiply the wddth by the thickness, which is 
 .5 X .5 = .25 area at point of fracture. Let us also 
 
14 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 assume that the strain at which our test piece parted 
 is 15,000 pounds, therefore 15,000 -^ .5 X .5 = 
 60,000 pounds tensile strength per square inch. 
 
 J 
 
 l-2x1-2iN. 
 
 Half inch thick half inch wide. 
 
 .25)15,000.00(60,000 tensile strength 
 150 
 
 What Advantage Does Steel Have Over Iron? 
 
 First, it is Hghter; second, it is stronger; third, 
 its condensing power is higher; for instance, it will 
 evaporate 25 per cent, more water with the same 
 amount of fuel in a given time. Steel boilers are 
 more free from corrosion than iron on account 
 of the density and compactness of the material. 
 
 Construction of a steam gauge. 
 
 The principle of a dial steam gauge is that the 
 pressure may be indicated by means of a pointer 
 in a divided dial similar to a clock face, but marked 
 in division, indicating pound pressure per square 
 inch above the atmospheric pressure, and shows 
 the ordinary style of gauge, which consists of an 
 elliptical tube connected at one end to a steam pipe 
 in connection with the boiler pressure. 
 
 Q. What causes pitting in a boiler? 
 
 A. An acid which generally comes from animal oil. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 15 
 
 Q. How should pitting in a boiler be treated? 
 
 A. First it should be scraped and cleaned with a 
 strong solution of soda or coal oil to remove grease 
 and acids and then covered with a thin coat of white 
 zinc to fill up the pit holes to prevent further pitting. 
 
 Q. What benefit is derived from circulation of 
 the water in a Scotch boiler when the engine is 
 stopped ? 
 
 A. The boiler is kept at a more equal tempera- 
 ture, and contraction and expansion is not so great. 
 
 Q. Where is the most pressure on a boiler and 
 why? 
 
 A. A boiler when filled with water, and when it 
 has a steam pressure, contains the most at the 
 bottom, because the bottom has the weight of the 
 water plus the pressure of steam. 
 
 Q. What should be done if a boiler head were to 
 crack from one tube to the other? 
 
 A. One or more holes should be drilled into the 
 crack and tapped out, and in those holes, plugs 
 should be screwed and tapped and calked. 
 
 Q. Where would you look for pitting in a sta- 
 tionary boiler? 
 
 A. ^lost generally on the tubes, and sometimes 
 pitting takes place on the water line or a little below. 
 
 Q. Where would you look for pitting in a marine 
 boiler? 
 
 A. The fire line of the furnace, also around the 
 combustion chamber, and the back head and in some 
 Scotch boilers it is known to pit on the bottom of 
 the boiler. 
 
16 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Q. In what direction is the steam pressure in a 
 boiler exerted? 
 
 A. In all directions. 
 
 Q. Why is the butt joint of a boiler the strongest? 
 
 A. The butt joint is the strongest because it is 
 a true circle. 
 
 Q. Why are the short screw stay bolts turned 
 smooth in the centre? 
 
 A. They are turned smooth in the centre to pre- 
 vent corrosion, as a smooth surface does not corrode 
 as quickly as it does in rough stays. 
 
 Q. Why is a large factor of safety used for boiler 
 stays? 
 
 A. A large factor of safety is used to allow for 
 corrosion or eating away of the metal. 
 
 Q. What are the four principal points to consider 
 in cylinder boilers for carrying high steam pressure? 
 
 A. First, the tensile strength; second, diameter; 
 third, pitch and size of rivet; fourth, thickness of 
 plate. 
 
 Q. Will a boiler 72 inches in diameter f thick 
 made of iron stand as much pressure as a boiler 
 48 inches in diameter and | thick? 
 
 A. No. 
 
 Q. Why? 
 
 A. Because the pressure in a large boiler has 
 more surface and will not allow it. It is the same 
 as a long bar of the same thickness. It takes less 
 to break the small one than the short one. 
 
 Q. How do you ascertain if your shaft is out of 
 line? 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 17 
 
 A. Take the coupling bolts out of the coupling, 
 and if the coupling faces up square the shaft is in 
 line. 
 
 Q. How is it arranged sometimes to give a boiler 
 more power? 
 
 A. By using a forced draft. 
 
 Explain the Thermometer 
 
 A thermometer is based on the change of volume 
 to which bodies are subject with the change of 
 temperature. A thermometer is filled with air, 
 water, or mercury. It consists of a tube of glass 
 formed with a bulb at the bottom filled with mer- 
 cury, and it is graduated in numbers: blood heat, 
 100°; temperature, 52°; freezing, 32°. Boiling- 
 point is divided into 180°, freezing being 32° and 
 boiling 212°. 
 
 Q. Name the different kinds of compound engines ? 
 
 A. Tandem cross, high-pressure, low-pressure, 
 triple expansion, and quadruple expansion. 
 
 Q. How much larger is the low-pressure cylinder 
 than the high-pressure cylinder? 
 
 A. Twice the area of the high-pressure cylinder. 
 
 Q. How is the horse power of a non-condensing 
 compound engine found? 
 
 A. By finding the area of each cylinder separately, 
 then adding them together and dividing by two to 
 get the average. Then the mean effective pressure 
 is found by adding the two mean effective pressures 
 together and divide by two less the back pressure. 
 
18 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Q. What is a surface condenser? 
 
 A. It is where the exhaust steam flows around 
 cold tubes that the circulating water passes through 
 condenses the steam into water. It drops to the 
 bottom of the condenser, is then taken out by an 
 air pump and pumped back to the boiler. 
 
 What is a Jet Condenser 
 
 A. It is a chamber in which the exhaust is com- 
 pelled to pass through a spray or a jet of cold water, 
 and after condensed it mixes with the injection 
 water into a hot well and from there some is pumped 
 in the boiler and the balance is pumped overboard. 
 
 Q. Which is the most economical of the two, a 
 jet or a surface condenser? 
 
 A. The jet for stationary work, because it uses 
 less water. 
 
 Corliss Engine 
 
 Q. How is a Corliss engine valve set and adjusted? 
 
 A. First take ofi^ the back caps of all four valve 
 chambers. Lines will be found on the end of the 
 chambers which show the working edge of the ports 
 and valves and the lap and lead. The wrist plate 
 central located between the four valves has three 
 lines on top of its hub edge, and correspond with 
 the single lines on top of the brackets. They show 
 the central and two positions of four valves. The 
 valve is next adjusted by unhooking the reach rod 
 from the wrist-plate pin, then hold the wrist plate 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 19 
 
 in the central position, and by means of right and 
 left thread rods, adjust each valve singly. Set the 
 steam so they will have J inch lap for a 10-inch 
 cylinder and J-inch lap for 32-inch cylinder. Ex- 
 haust valves should have yV lap for 10-inch cylinder, 
 I for 32-inch cylinder. For high-pressure no lap- 
 condensing engine gives nearly double the lap. 
 
 Q. After making those adjustments what is to 
 be done? 
 
 A. The dash pot rods are adjusted by turning 
 the wrist plate to its extreme of travel and adjust 
 each rod so that when the rod is down as far as it 
 will go the stud on the valve arm will just clear the 
 latch on the latch hook. 
 
 Q. If the rod is too long or too short what is to 
 be done? 
 
 A. If the rod is too short the hook will not drop 
 in; the valve will not open. 
 
 Q. How much salt would you allow the water to 
 get in a boiler with a jet condenser and surface con- 
 denser? 
 
 A. Not over li to 3%. 
 
 Salinometer 
 
 A salinometer is a glass or a metal instrument 
 by which the density of water is ascertained. It 
 consists of a weighted bulb, to which is attached 
 graduated steam, and its action is to indicate the 
 amount of salt held in solution in the water by 
 floating higher or lower — higher for density and 
 
20 MAKINE AND STATIONARY ENGINEERS CATECHISM 
 
 lower for freshness. Some are graduated into 33 
 rods and some to 32 rods, each representing about 
 five ounces of salt to a gallon of water. Care must 
 be taken to use the salinometer at the temperature 
 for which it is marked, as the density of fluids vary 
 in proportion to their temperature, 200° being the 
 usual temperature of the water in which these 
 instruments are tested, so that they may be used 
 almost immediately on the water from the boiler. 
 
 Sea water contains ^V part salt — that is, if 32 
 pounds of sea water were evaporated one pound 
 of salt would remain. ^V is for this reason taken 
 as the unit by which to measure the density of the 
 boiler water. If the water in the boiler has the same 
 amount of salt in it as sea water, we say it has one 
 degree of salt; if it contains twice as much salt per 
 gallon as sea water, then it has two degrees of salt 
 — that is, ^% salt; five ounces of salt to a gallon. 
 Do not let the water in the boiler get over 1 J or -^ 
 salt in the boiler. 
 
 Q. Could you make a salinometer if you had 
 none? 
 
 A. Yes; take a bottle and weight it down so 
 it will fioat upright, then take some fresh water 
 and put it on some hot coal and boil it to 190° or 
 200°, then place the bottle in the fresh water and 
 mark the bottle at the fresh water line; then take 
 some salt water out of the sea and boil it 190° or 
 200°; then you will find the bottle will raise -j^, the 
 difference between fresh water and salt water. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 21 
 
 Indicator 
 
 Q. What is the use of an indicator on an engine 
 and what information does it give? 
 
 A. It shows the expansion of steam in the cylinder, 
 also if the valves are properly set and adjusted. 
 
 Q. How many lines does the indicator card show 
 when steam is against the indicator piston, also 
 when turned off? 
 
 A. Seven lines: six with steam — namely, compres- 
 sion, admission, steam, expansion, release, and 
 exhaust. 
 
 Q. When steam is turned off the indicator, the 
 atmosphere line is drawn, making the seven, are 
 there any other lines drawn on the card, and if so, 
 when? 
 
 A. Yes, two, the vacuum and clearance lines. 
 They are drawn after the card has been laid out on 
 a flat surface board. 
 
 Q. How are cards measured and calculated to 
 find the M. E. P.? 
 
 A. By dividing the length of the card into 10 
 equal parts by drawing perpendicular lines in regular 
 order called ordinates from the steam end to expan- 
 sion line down to the atmosphere line. 
 
 Q. After the card has been properly laid out 
 what should be done? 
 
 A. Take a strip of paper | inch wide and about 
 12 inches long. Lay it alongside of the first ordi- 
 nate, mark the length, then lay the strip up to the 
 
22 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 second ordinate so its length will be added to the 
 first, and so on until all the 10 ordinates will be in 
 one straight line. Then take total measurement 
 in inches. Suppose the total length w^as 9 inches 
 long and the spring was 30 pounds, how is the 
 M. E. P. found? 
 
 A. The card is 9 inches long X by the spring 
 30 pounds divided by 10 ordinate. 
 
 30 spring 
 9 length of card 
 
 ordinate 10)270(27 mean effective pressure 
 20 
 
 70 
 70 
 
 Q. What is meant by M. E. P.? 
 
 A. It is the mean effective pressure of steam that 
 is on the piston throughout the stroke less the 
 back pressure. 
 
 Q. How is the horse power of an engine found 
 when the M. E. P. is known? 
 
 A. Find the area of piston X by M. E. P. X by 
 piston speed in feet per minute and divide by 
 33,000. This equals the horse-power. 
 
 A. Diameter of cylinder, 20 inches; stroke of 
 engine, 20 inches; mean effective pressure on piston, 
 27 pounds; revolutions per minute, 120. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 23 
 
 Example to Find the Horse-Power 
 
 20 in. stroke 20 diameter of cylinder 
 
 20 20 
 
 40 inches 400 
 
 120 revolution 
 .7854 
 
 800 400 
 
 40 
 
 314 . 1600 area of piston 
 
 12)4800(400 feet per minute 27 M. E. pressure 
 
 48 
 
 21991200 
 6283200 
 
 8482.3200 
 
 400 feet per minute 
 
 33000)3392928 . 0000(102 . 8 horse-power 
 33 
 
 92 
 66 
 
 269 
 
 264 
 
 Another Way to Get the Horse-Power 
 
 To get the horse-power of indicator card, first 
 get the square inches in the cyHnder, then mul- 
 tiply that by .7854 to get the area, then multiply 
 the area by twice the stroke in feet multiplied by 
 revolution and divide by 33,000; that will give the 
 constant; then count the card up to get the M. E. P. 
 We will say the M. E. P. is 40 on the piston. Mul- 
 tiply half the card by the constant, half the card is 
 20 pounds, that will give the horse-power of the 
 
24 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 engine and deduct the atmospheric pressure from 
 the horse-power. We will take the diameter of the 
 cylinder 18 inches, 18-inch stroke 100 revolutions 
 per minute, allowing 33,000 pounds per horse-power. 
 
 Example 
 
 18 stroke of engine 
 
 18 
 
 36 
 100 revolution 
 
 12)3600(300 feet 
 36 
 
 18 diameter cylinder 
 
 18 
 
 144 
 
 18 
 
 324 square of cylinder 
 
 .7854- 
 324 
 
 31416 
 15708 
 23562 
 
 
 254.4696 
 
 300 feet per minute 
 
 33,000)76340.8800(2.31 constant 
 66000 
 
 103408 
 99000 
 
 2.31 constant 
 20 half card 
 
 44088 
 33000 
 
 46.20 
 
 This example is to get the M. E. P. of card on 
 piston mean effective pressure on piston 40. 
 
 Horse power is 46.20. 
 
 Q. If at sea and the water in the boiler was gaining 
 where would you look for the trouble and what 
 would vou do? 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 25 
 
 A. Try the water in the filter box or hot well for 
 salt, if I found the water salt I would try all valves 
 that were attached to the condenser from the sea, 
 if I found them all right I would see if the discharge 
 from the air pump was taking in water as it some- 
 times does when a ship is rolling deep and if the 
 water still continues to gain in the boiler I would 
 give each boiler a little blow and when in port take 
 off condenser heads and plug tubes. 
 
 Q. Why is too late admission loss of power? 
 
 A. Too late admission is a loss of power because 
 the piston has travelled a part of the stroke before 
 the steam has attained to its full pressure. Late 
 admission means that the valve has no lead. 
 
 Q. If the high pressure of a compound engine 
 was on the centre, how would you start it? 
 
 A. Admit steam to the low pressure cylinder. 
 
 Q. How much lap should a piston valve 
 have? 
 
 A. About the same as a slide valve has. 
 
 Q. Which will have the most lap exhaust or piston 
 valve? 
 
 A. There is not any difference. 
 
 Q. From which end of the cylinder does the piston 
 travel the faster? 
 
 A. It always travels the faster on leaving the 
 head end of the cylinder on account of the weight 
 of the connecting rod and piston. 
 
 Q. How would you run a tandem compound 
 engine if either high or low valve stem should 
 break? 
 
2G MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 A. If high valve stem should break, take out 
 the valve and run with a reduced boiler pressure; 
 if the low valve stem should break, take out the 
 valve and run as a simple. 
 
 Q. If a crank broke on the high pressure side of 
 a cross compound engine how would you run it? 
 
 A. Take out valve, block piston and crank, and 
 run with a reduced pressure. 
 
 Q. How would you run if crank broke on low 
 pressure side? 
 
 A. Take out low-pressure valve, block the piston 
 at its crank, and run as above. 
 
 Q. How would you set the valves on a Corliss 
 engine to run high pressure? 
 
 A. Set the steam valves with f of an inch lap; 
 exhaust valve line and line when the wrist plate 
 was central and hook in, and make further adjust- 
 ment with the indicator. 
 
 Q. How would you set them to run on a condenser? 
 
 A. With a little more lead and a little earlier 
 compression. 
 
 Q. What advantage do we get in having an eccen- 
 tric on a Corliss engine? 
 
 A. Greater range of cut off. 
 
 Q. Should there be two wrist plates? 
 
 A. It's not necessary. 
 
 Q. Why do we give more lap on the steam valve 
 of a large Corliss engine than we do to the small one? 
 
 A. To get earlier compression. 
 
 Q. How would you give a Corliss engine more 
 lead without giving it more compression? 
 
MARINE AND STATIONARY ENGINEERS CATECHISM Z / 
 
 A. Shorten the steam hnk. 
 
 Q. How would you give Corhss engine more 
 compression? 
 
 A. Advance the eccentric, making the required 
 change or lengthening steam links. 
 
 Q. Does the eccentric set ahead or behind the 
 crank of an automatic engine and why? 
 
 A. If the engine is to run ahead, the eccentric 
 sets behind the crank, because it is a direct 
 motion with the piston and indirect from the 
 governor. 
 
 Q. What is a cross compound engine? 
 
 A. One in which the cylinders set side by side and 
 with cranks usually at right angles to each crank. 
 
 Q. What is a tandem compound engine? 
 
 A. One in which one cylinder seats ahead of the 
 other on the same piston rod and connected to the 
 same crank. 
 
 Q. Why is a compound engine more economical 
 than a simple engine, when the steam pressure is the 
 same? 
 
 A. Smaller ports and less condensation. 
 
 Q. If you were at sea and your high-pressure 
 engine became disabled beyond repairs, how would 
 you proceed? 
 
 A. Disconnect your high-pressure engine and run 
 with your after engine. 
 
 Q. Describe just what you would do upon enter- 
 ing your engine room in the morning, the plant 
 being shut down under fires banked through the 
 night? 
 
28 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 A. The first duty of an engineer when entering 
 his plant at any time is to ascertain how the water 
 in the boiler stands; he should open the gauge 
 cocks and note what came from each in turn, then 
 open the cocks or valves connected to the water 
 glass gauge, and note the water line there shown; 
 he should also blow the water column out in case 
 any sediment may have choked any of the passage 
 which would be liable to give a false impression 
 as to the actual quantity of water contained in the 
 boiler. Should the water be found at the correct 
 height, he may now proceed tohaulhis fires down; then 
 when the boiler has made about 25 or 30 pounds of 
 steam, you should give your boiler a good blow down. 
 
 Q. How would you find travel of a valve having 
 a steam lap of f of an inch and a maximum port 
 opening of If inches? 
 
 A. The maximum port opening at the head end 
 plus the lap at the head plus lap at the crank end 
 11 + 11 + 4 + 1 = 4i the required travel of the 
 valve. It is well to give practical methods. The 
 travel of any valve is obtained from the eccentric 
 by subtracting the thin part of the eccentric from 
 the thick part of the eccentric, is termed the throw 
 of the eccentric. 
 
 Q. Can a proper vacuum be formed? 
 
 A. No, about 9 to 11 per cent, of the atmospheric 
 pressure, which is 14.7 pounds per square inch. 
 
 Q. What will vacuum do? 
 
 A. It will raise water 33 feet, providing all pipes 
 and connections are air-tight. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 29 
 
 Q. Name the different things that will affect the 
 vacuum in a condenser. 
 
 A. Extra feed valves being open after tank is 
 empty, circulating pump running too slow, condenser 
 being too small, dirty tubes, low-pressure piston 
 packing too loose in stuffing-box, air-pump valves 
 or piston packing bad, or any leak that will admit 
 air in condenser. 
 
 Q. If you were compelled to change from 
 surface to a jet condenser, how would you 
 proceed? 
 
 A. Stop circulating pump if it is working; start 
 the engine and open the jet valve on condenser 
 slowly, until I have it open enough to form twenty 
 inches of vacuum or more. 
 
 Q. What would be the result if you opened the 
 jet valve too much? 
 
 A. You would admit too much water to the con- 
 denser, therefore cutting too much load on the air- 
 pump. 
 
 Q. If you were running jet condenser and you 
 stopped, what would you do? 
 
 A. Shut off the injection valve to condenser. 
 
 Q. Why would you shut off injection valve to 
 condenser? 
 
 A. To hold the vacuum in the condenser as long 
 as possible and not to flood the condenser. 
 
 Q. Explain how shutting off injection valve on 
 the condenser w^ould hold the vacuum? 
 
 A. As vacuum is a space void of all pressure and 
 you leave any valve open that will admit air or 
 
30 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 water, you will have atmosphere or water pressure 
 in your condenser. 
 
 Q. If you had atmosphere or water pressure in 
 your condenser how would it effect the engine 
 starting? 
 
 A. It would cause the engine to start bad, and put 
 on extra load on the air-pump and discharge pipe; 
 it has been known to cause a break down. 
 
 Q. Why is a condenser used? 
 
 A. To relieve the engine of back pressure and 
 maintain fresh water for the boiler. 
 
 Q. If you were at sea and your circulation pump 
 became disabled, how would you get into port? 
 
 A. Run jet condenser; if not, run high-pressure. 
 
 Q. If your air-pump were to break down and you 
 had no other pump to take its place, what would 
 you do? 
 
 A. Keep the circulation pump running, take 
 oft' bottom plates on condenser, let the condensed 
 water run in the bilge, and pump it out. 
 
 Q. If you had no water jet on your condenser, 
 how would you make a jet condenser out of a sur- 
 face condenser? 
 
 A. By taking out enough tubes to supply the 
 condenser with water to condense steam and use 
 the sea cock for the jet valve. 
 
 Q. Why will a pump refuse to lift hot water? 
 
 A. A pump will refuse to lift hot water because 
 the vapor will rise and prevent a vacuum from being 
 formed, and consequently an unbalanced condition 
 of pressure cannot exist which is necessary to cause 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 31 
 
 the water to flow up to the pump, therefore if you 
 want to pump hot water place the pump so that the 
 hot water will run to it. 
 
 Evaporation of Water and Coal Burn 
 
 Q. How many pounds of water would you expect 
 a pound of coal to evaporate, and how many pounds 
 of water required per hour for triple expansion 
 engine? 
 
 A. A good boiler will evaporate ten pounds of 
 water under ordinary circumstances, but it depends 
 upon the efficiency of the boiler, the quality of coal, 
 the temperature of the feed water and the tempera- 
 ture of which steam is generated. A triple expan- 
 sion engine requires eleven or twelve pounds of 
 water per hour. 
 
 Q. How much water will a pound of coal evaporate ? 
 
 A. The average is about one gallon per pound of 
 coal. 
 
 Q. What is the consumption of coal per square 
 foot of grate surface in a steam boiler? 
 
 A. With natural draft about ten to twelve pounds 
 per square foot of grate surface. 
 
 Q. What is the water consumption in pounds 
 per hour indicated horse power? 
 
 A. From 25 pounds to 60 pounds. 
 
 Q. What is lead on a valve? 
 
 A. Lead is the distance or amount that the valve 
 comes short of covering the port when the piston is 
 at the beginning of the stroke. 
 
32 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Q. How many kinds of lead are there? 
 
 A. There are two kmds outside or steam lead 
 and inside or exhaust lead, outside or steam lead is 
 the distance that the outside or steam side edge of 
 the valve comes short of covering the port when 
 the piston is at the beginning of the stroke, inside or 
 exhaust side edge of the valve comes short of cover- 
 ing the port when the piston is at beginning of the 
 stroke. 
 
 Q. How do you give an engine more lead? 
 
 A. By advancing the eccentric on the shaft. 
 
 Q. What effect has too much lead on an engine? 
 
 A. It causes the engine to pound also forms too 
 much cushioning. 
 
 Q. What is the use of lap on a valve? 
 
 A. Give the engine compression and also to work 
 the steam expansively. 
 
 Q. What is the use of a valve? 
 
 A. It regulates the flow of steam to and from 
 cylinder. 
 
 Q. What use is a link on an engine? 
 
 A. To cut off the steam at different parts of stroke. 
 
 Q. How much heating surface is allowed per 
 horse-power in a boiler? 
 
 A. Twelve to fifteen square feet. 
 
 Q. How do you find the proper size of a safety 
 valve to be placed on a boiler? 
 
 A. Three square feet of grate surface is allowed 
 for one inch of area of valve. 
 
 Q. How hot can you get water under atmospheric 
 pressure with exhaust steam? 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 33 
 
 A. 212 degrees. 
 
 Q. What is meant by atmospheric pressure? 
 
 A. The weight of the atmosphere. 
 
 Q. What is the weight of the atmospheric pressure 
 at the sea level? 
 
 A. 14.7 pounds. 
 
 Q. How many pounds of water can be evaporated 
 with one pound of the best soft coal? 
 
 A. From 7 to 10 pounds. 
 
 Q. W'hy do we condense steam? 
 
 A. To form a vacuum and so destroy the back 
 pressure that would otherwise be on the piston and 
 thus get more useful work out of the steam. 
 
 Q. W'hat is meant by horse-power? 
 
 A. Horse-power is equivalent to raising 33,000 
 pounds one foot high per minute. 
 
 Q. What is meant by a triple expansion engine? 
 
 A. A triple expansion engine has three cylinders 
 using the steam expansively in each cylinder. 
 
 Q. What is meant by using steam expansively? 
 
 A. When the steam is admitted at a certain 
 pressure, is cut off, and allowed to expand to a lower 
 pressure. 
 
 Q. What would you do if you were to knock your 
 top cylinder head out of your compound engine 
 beyond repairs? 
 
 A. Block the steam ports so as not to admit 
 any steam on the top end of the piston, reduce 
 steam pressure and proceed. If it sticks on the centre 
 put a liner under the eccentric rod so as to admit 
 more steam on the bottom of the piston. 
 
34 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Q. What would you do if you broke a low pres- 
 sure connecting rod on compound engine? 
 
 A. Use the high-pressure connecting rod and put 
 it in the low, then take high-pressure vailve out, 
 so as to let steam pass over into the low-pressure 
 valve, then let the high-pressure piston down to the 
 bottom of the cylinder, then reduce steam pressure. 
 
 Q. What is the object of putting zinc plates in a 
 boiler? 
 
 A. It causes a galvanic action and the acids in 
 the water act directly in the zinc plates instead of 
 on the boiler plates and shell. 
 
 Q. How often should the zinc plates be renewed? 
 
 A. As often as they are corroded and eaten away. 
 
 Q. To find the scale of the spring for taking a 
 diagram from high-pressure cylinder? 
 
 A. Divide the gauge pressure by 2i. 
 
 Q. In a triple-expansion engine with second 
 cylinder doing much more work than low pressure, 
 how can your cut off be best adjusted in either cylin- 
 ders to balance load between cylinders? 
 
 A. By shortening the cut off on the low^-pressure 
 cylinder t lus increasing the back pressure on inter- 
 mediate reducing the pressure on it, also the back 
 pressure on the high-pressure cylinder. 
 
 Q. What is the effect on receiver pressure of 
 cutting off later in first cylinder? 
 
 A. The receiver pressure will be raised and the 
 engine will perform more work. Tie low pressure 
 piston in this case will perform more work than the 
 high pressure piston on the former. The pressure 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 35 
 
 is increased, while on the latter the back pressure, 
 the cut off, and has to be regulated for both cylinders 
 to make them perform even share of the work. 
 
 Q. Name the bad features of the keel condenser? 
 
 A. Two bad features of the keel condenser are 
 that the water will not flow good to the air pump, 
 and if the climate is cold enough to bring the water 
 on the outside of the condenser down to a freezing 
 point the fresh water in the condenser will freeze 
 solid, and that will be an extra expense. 
 
 Q. Can the heat of steam be raised to a very 
 high temperature? 
 
 A. Steam can be heated to nearly a red heat, 
 but not while it is held in contact with water. 
 
 Q. How is it arranged sometimes to give a boiler 
 more power? 
 
 A. By using forced draft. 
 
 Q. Are holes drilled or punched in a boiler? 
 
 A. They are drilled in a boiler. 
 
 Q. What would be the result of incorrect length 
 of eccentric rod? 
 
 A. Too much lead on the rod or not enough lead. 
 
 Q. The question is very often asked why they 
 use a piston valve? 
 
 A. You take a 10 inch piston valve, the area is 
 78 inches with 120 pounds of steam would be 78 
 inches X by 120 = 93.60 pounds per square inch 
 of area on piston valve, take a flat valve 14 inches 
 wide and 24 inches long would be 24 X 14 inches 
 3.36 square inches X by 120 pounds of steam = 
 403.20; the flat valve has 309.60 pounds more pres- 
 
36 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 sure than a piston valve; the piston valve has less 
 friction by 309.60 pounds. 
 
 Q. Which is the best way to run a stationary 
 engine, over or under? 
 
 A. Over, because the pressure of the crosshead and 
 the main shaft is downward on the foundation 
 instead of up against the guide or caps. 
 
 Q. The question is often asked what is the best 
 way to set a piston valve? 
 
 A. Place the engine on top or bottom centre, 
 place the piston valve in its place, then give the 
 piston valve the full opening of the exhaust and the 
 piston valve is set nearly correct. 
 
 Dynamo Electric Questions 
 
 A dynamo is a machine by means of which 
 mechanical energy is converted into electric energy. 
 A dynamo electric generator or dynamo electric 
 machine is ordinarily constructed as follows: Parts: 
 armature, the field magnets, the commutator, and 
 collecting brushes. A dynamo is classified under two 
 headings: first, direct current generator; second, 
 alternating current generator. The direct current 
 generator is divided into series wound machine, 
 shunt wound machine and compound wound machine ; 
 and the alternating current are classified with respect 
 to the character of the current they develop. In 
 this case it may be said that there are single-phase 
 machines and two-phase machines and three-phase 
 machines. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 87 
 
 Among alternating- current generators are found 
 forms of construction of a space character in which 
 neither the armature wire nor the field being pro- 
 duced. The series wound dynamo is generally em- 
 ployed for a system of electric lighting in which a 
 constant current is necessary, such as high-tension 
 arc lighting. For instance the function of this 
 type of generator is to provide a current of 10 or 12 
 amperes and a voltage that is capable of being 
 adjusted by special means to suit the number of 
 lamps in use. The arc lamps are connected in series. 
 Each lamp takes the same amount of voltage. 
 If tw^enty or thirty lamps are connected twenty or 
 thirty times the volts required for one lamp is the 
 total voltage to be generated and would equal 
 20 X 50 or from 1000 to 1500 volts. Arc lamps 
 as now used may be of the open or closed arc type; 
 by this is meant that the carbon either burns in 
 the open air, lasting only about eight or ten hours, 
 or enclosed in small globe. Each lamp takes 50 volts 
 if of the open air type; if of the closed globe type, 
 each lamp will take about 80 volts. The dynamo 
 must be able to automatically raise or lower its 
 voltage when the lamps are turned on or off. 
 When more lamps are added to the line, more 
 voltage will be required. In fact, as much more as 
 there are extra lamps. When lamps are cut off, 
 less voltage will be required in proportion to the 
 number of lamps. For instance, if ten of the closed 
 globe type are added to the circuit of a series wound 
 dynamo by simply turning them on, 10 X 80 or 800 
 
38 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 volts more must be sent into the line; on the other 
 hand, if 10 lamps are cut out 800 volts less in the 
 line will do. 
 
 Sparking on a Dynamo 
 
 Sparking may be caused by too great a load on 
 the dynamo or by wrong position of the brushes. 
 One brush may not be opposite the other in a two 
 pole machine, or the brushes may not be properly 
 adjusted on the commutator if they belong to a 
 multipolar machine On a four pole machine they 
 should be 90 degrees apart; on a six pole machine, 
 60 degrees apart. The simplest way of getting the 
 correct distance between brushes is to count the 
 commutator bars and divide them by the numbers 
 of poles of the generator. Sometimes sparking at 
 the commutator is caused by the bars being loose; 
 or the mica and the bars may be projecting beyond 
 the brushes. In general the difficulty is frequently 
 found in the more rapid wearing away of the copper 
 bars before the mica itself has worn down. The 
 mica • is harder than might be expected, and the 
 brushes do not affect it. Sandpapering the commu- 
 tator is of little or no use; the only remedy is the 
 turning down of the commutator. The best way to 
 do this is by a lathe or by a special commutator 
 turning device. 
 
 Q. How do the alternating and the direct 
 current generators differ? 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 39 
 
 A. The direct current generator uses a commutator 
 in order to send out a current. Following always 
 in the same direction alternating current generators 
 use collecting rings, which permit all the alterna- 
 tions generated within the armature to occur outside 
 in connecting circuits. 
 
 Q. What reverses the direction of a current in 
 a conductor? 
 
 A. The fact that it has being moved past a north 
 pole or a south pole. The electro-motive force tends 
 to send a current in one direction when the conduc- 
 tor passes a north pole and in the reverse direction 
 when it passes a south pole. 
 
 Q. What is the action of the commutator and 
 brushes? 
 
 A. To permit all positive impulses to flow into 
 one brush or set of brushes and all negative impulses 
 to flow^ into the other brushes or other set of brushes. 
 
 Q. What causes heating a commutator? 
 
 A. Bad contact between the brushes and the com- 
 mutator, a small commutator, too much pressure 
 from the brushes, or a brush of too great a resistance. 
 
 A brush should never be lifted off the com- 
 mutator while the dynamo is running. Every 
 binding screw should be examined, and if necessary 
 tightened every day, as they are liable to be loosened 
 by a slight jar of the dynamo. 
 
 It is advisable to run a new dynamo a few 
 hours or even a day without any load on in order 
 to have everything in proper working order before 
 putting on the load, which should be done gradually. 
 
40 marine and stationary engineers catechism 
 
 Starting and Charging an Ammonia Compressor 
 
 As each type of ammonia compressor has its own 
 feature of construction, each particular machine 
 will require special care and laid down to suit all 
 cases. There are, however, some general principles 
 which are attached to all types based on the com- 
 pression system. Before charging an empty machine 
 with ammonia all air must first be expelled, this 
 is done in various ways, one method often used is 
 to pump the system full of gaseous ammonia and 
 shut the engine down, allowing the water to flow 
 in the condensor until all the ammonia in the system 
 is condensed, the liquid ammonia being heavier 
 will drop to the bottom of the system, the valve 
 can then be opened at the highest part of the system 
 and the pressure of the ammonia gas will indicate 
 when to shut off the valve, the system can then 
 be allowed to stand six or twelve hours, and the 
 valve again opened; if there is any air remaining 
 in the system it will be driven out when the valve 
 is again opened. Before charging the system 
 it can be thoroughly tested by working the com- 
 pressor and permitting air to enter at the suction 
 through the special valve provided for that purpose, 
 and it should be perfectly tight at 200 or 250 pounds 
 per square inch, and should be able to hold that 
 pressure without loss while testing the system 
 under air pressure. It should be carefully and 
 thoroughly cleaned of all dirt and moisture by 
 blowing out. In some cases it is impossible to get 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 41 
 
 rid of all of the air from the phirit by means of the 
 compressor, therefore, it is advisable to insert the 
 requested charge of ammonia gradually; sometimes 
 from 60 to 70 per cent, of the fuel charge is put in, 
 and the air remaining in the system is allowed to 
 escape through the purging cocks with as little 
 loss of gas as possible; subsequently an additional 
 quantity of ammonia, once or twice a day, is inserted 
 until all the air has been displaced and the complete 
 charge has been introduced. To charge the machine 
 the drum of ammonia is connected through a suit- 
 able pipe to the charging valve. The machine 
 should be run at a slow speed when sucking the 
 ammonia from the tank, with the discharge and 
 suction valve wide open. When one of the tanks 
 is emptied the charging valve is closed and another 
 tank placed in position, and the process continued 
 until the machine is charged for work, when the 
 charging valve can be closed, and the main expan- 
 sion valve opened and regulated. A glass gajuge 
 upon the liquid receiver will show" w^hen the latter 
 is partially filled and the pressure gauge, as well as 
 the gradual cooling of the brine in the refrigerator 
 and the expansion pipe, being covered with frost, 
 will indicate when sufficient ammonia to start work- 
 ing has been inserted. The machine having been 
 started and the regulating valve opened the tempera- 
 ture of the delivery pipe should be carefully noted, 
 and if it shows a tendency to heat, then the regu- 
 lating valve must be opened wider; while if it should 
 become cold, the valve must be slightly closed, the 
 
42 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 regulation or adjustment thereof being continued 
 until the temperature of the pipe is the same as the 
 cooling water which leaves the condenser if the 
 charge of ammonia is insufficient, the delivery pipe 
 will become heated. Even the regulating valve 
 is wide open. Among the signs which denote the 
 healthy working of the plant, beside the fact that it 
 is satisfactorily performing its proper refrigerating 
 duty, the vibration of the pointer of the pressure 
 and vacuum gauge which clearly makes every 
 stroke of the piston, the frost on the exterior of the 
 ammonia pipes, the liquid ammonia can be dis- 
 tinctly heard pouring through the regulation valve 
 in a continuous stream, and the difference in tem- 
 perature between the condenser and the cooling 
 water and the refrigerator and the brine. 
 
 Q. Does the temperature of steam at ordinary 
 pressure contain heat enough to ignite wood? 
 
 A. Not without the intervention of some other 
 substance, such as linseed oil, greasy rags, or iron 
 turnings. 
 
 Q. How do you explain that? 
 
 A. Because we know that the temperature of 
 superheated steam is only about 400° Fahrenheit, 
 and it requires more than double that temperature 
 to ignite wood. 
 
 Q. How is the power of steam engine expressed? 
 
 A. In a horse-power. 
 
 Q. What is a nominal horse-power? 
 
 A. 33,000 pounds raised one foot high in one 
 minute. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 48 
 
 Q. Why is it that 33,000 pounds raised one foot 
 high in one minute is adopted as a standard for a 
 steam engine? 
 
 A. Before the introduction of the steam engine 
 it was found by experiment that with the average 
 horse the best speed for work was at the rate of 
 2| miles per hour, and at that rate of speed a 
 horse could raise at perpendicular a weight of 
 150 pounds 220 feet high in one minute, which is 
 equivalent to 33,000 pounds raised one foot high in 
 one minute, and was taken by Watt^ as a standard 
 for a horse-power, and is universally received as 
 such. For instance, an engine of 60 horse-power 
 can raise 33,000 pounds one foot high in a second 
 or an engine of 420 horse-power w^ould raise 33,000 
 pounds one foot high in y of a second. 
 
 Q. The question is often asked why is it necessary 
 to make the longitudinal seams so much stronger 
 than the transverse or girth seam. 
 
 A. The reason is that the strain on the longitudinal 
 seam is twice that of the transverse seam. In some 
 types of boilers it is more than twice, for in the return 
 tubular or a boiler having tubes and stays from head 
 to head they relieve the transverse seam while the 
 longitudinal seam has the full load to carry. On 
 the transverse or girth seam the pressure would be 
 the area of the head being required of the diameter 
 2 X .7854 by the total pressure strain this pressure 
 acts endwise along the boiler tending to pull it 
 apart, and it is withstood by the plate of the boiler, 
 and where this comes together at the girth seam 
 
44 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 the length of each girth seam is the same as the cir- 
 cumference of the boiler — that is, it is equal to 
 .7854 X by diameter squared X by the pressure 
 divided by 3.1416 X by diameter, since 3.1416 is 
 exactly 4 times .7854, we find from the above cal- 
 culation that the strain on the girth seam per inch 
 of its length is 
 
 diameter X by pressure 
 4 
 
 If a two inch pipe discharges 3600 gallons of water 
 per minute, what is the velocity in feet per second? 
 
 one minute 60)3600(60 
 
 360 60)60(1 
 
 60 
 
 one foot per second — 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 45 
 
 Rule for a Pump 
 
 A pump with a water end 5 inches in diameter 
 and the steam end 6 inches in diameter with 70 
 pounds pressure the pump is pumping against 
 100.8 pounds. Suppose you wanted to change the 
 water end of the pump to pump against 157.5 pounds 
 per square inch, what would be the diameter of 
 the pump end. 
 
 Diameter of pump is 5 X 5 = 25 square inches 
 X 100.8 pounds = 2520.0 -^ by the pressure the 
 pump is to pump against which is 157.5 = 16 and 
 the square root of 16 = 4 = diameter pump. 
 
 iameter 5 
 5 
 
 100.8 
 25 
 
 
 25 
 
 5040 
 2016 
 
 
 
 157.5)2520.0(16 
 1575 
 
 16(4 
 16 
 
 
 9450 
 9450 
 
 diameter of pump is 4 inches 
 
46 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Donkey Pump 
 
 To find the number of gallons a pump will pump 
 allowing 231 cubic inches to a gallon single acting 
 pump number of strokes per minute 100 diameter 
 of the pump 4 J. Length of stroke is 8 inches. 
 
 4 . 5 diameter of pump 
 4.5 
 
 225 
 
 180 
 
 20.25 
 
 .7854 
 
 8100 
 10125 
 16200 
 14175 
 
 15.904350 
 
 8 inch stroke 
 
 127.234800 
 
 100 revolutions 
 
 231)12723.480000(55.08 number of gallons per minute 
 1155 
 
 1173 
 1155 
 
 1848 
 1848 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 47 
 
 Donkey Pump 
 
 Take a pump with the steam end 6 inches in 
 diameter, 60 pounds of steam, the pump end is 
 4 inches in diameter, what pressure per square 
 inch will this pump pump against? 
 
 6 steam end 
 6 
 
 36 
 
 60 steam pressure 
 
 square of the 16)2160(135 pounds this pump will pump 
 pump end 16 against 
 
 56 
 
 Take the same pump to find the height the pump 
 will pump w^ater in feet. Take a constant of 2.305 
 X by the pressure the pump will pump against 
 that will give the height the pump will pump water 
 in feet. 
 
 2.305 
 
 135 the pump will pump against 
 
 11525 
 6915 
 2305 
 
 311.175 
 This pump will pump 311 feet high. 
 
48 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 The Horse-Power of a Pump 
 
 What is the horse-power of a pump with the 
 following dimension: Diameter of pump 10 inches, 
 revolutions per minute 80, 156 pounds total head 
 pressure per square inch on pump, stroke is 28 inches. 
 
 .7854 
 
 100 square of pump 
 
 78.5400 
 
 28 stroke 
 
 6283200 
 1570800 
 
 2199.1200 
 
 80 revolution per minute 
 
 one cubic 
 
 ft. 1728)175929.6000(101.8 cubic feet 
 
 101.8 cubic feet 
 62 . 5 pounds to cubic foot 
 
 5090 
 2036 
 6108 
 
 6362.50 
 
 156 total pressure on pump 
 
 3817500 
 3181250 
 636250 
 
 33,000)992550.00(30. 
 99 
 
 25 
 This pump is 30 horse-power and a little over. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 49 
 
 Donkey Pump Rule 
 
 If you were going to test your main boiler in 
 
 your ship to put 120 pounds of cold water pressure 
 
 on your main boilers, and if you had a donkey 
 
 boiler, what pressure of steam would you carry 
 
 on your donkey boiler to put 120 pounds of cold 
 
 water pressure on your main boilers with a pump 
 
 6 inches in diameter and the steam end 10 inches. 
 
 6 water end 
 6 
 
 36 
 
 120 cold water pressure 
 
 720 
 36 
 
 square of pump 100)4320 . (43 . 2 it v:ould take 44 -pounds 
 end 400 
 
 320 
 300 
 
 200 
 200 
 
 Q. What is the horse power of a boiler? 
 
 A. The evaporation of 30 pounds of water per 
 hour from feed water 100° Fahrenheit into steam 
 at 70 pounds' gauge pressure has been adopted as 
 the horse-power of a boiler. 
 
50 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 To find the thickness of a casting to stand a 
 certain pressure when you have the inside dimen- 
 sion and the steam pressure. We will say that 
 the casting is 20 inches inside diameter, 95 pounds 
 of steam. 
 
 Example 
 
 95X20 , „ „ 
 
 95 steam pressure 
 20 inside diameter 
 
 constant— 4,000) 1900 . 000( . 475 
 
 16000 . .475 
 
 30000 
 
 0.6 
 
 28000 1.075 thickness = Ij^ 
 
 20000 
 20000 
 
 To find the pressure on a guide slipper area of 
 piston X by total pressure X by length of crank 
 pin, divided by the area of the guide slipper X by 
 length of the connecting rod. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 51 
 
 To Find the Pressure on Crank Pin 
 
 Area of the piston X by total pressure divided 
 by the length of the crank pin X by diameter of 
 crank pin. 
 
 To Find the Pressure on Thruss Bearing 
 
 First get the horse-power of your engine, we will 
 say 175, revolutions 140, pitch of wheel is 5 feet; 
 allowing 2240 pounds to a ton then multiply 
 175 X 33,000 = 5775000 - 140 X by 5 - 700. 
 
 140 175 horse-power 
 5 33,000 
 
 700 525000 
 525 
 
 
 700)5775000(825000 
 5600 
 
 2240)825000(3.69 tons on shaft 
 6720 
 
 1750 
 1400 
 
 15300 
 13440 
 
 3500 
 3500 
 
 18600 
 17920 
 
 three tons and over half ton 
 
OZ MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Side Wheel Steamer 
 
 To find the number of revolutions that a steam 
 engine has to make per minute with a paddle wheel 
 17 feet in diameter to make 17 J miles per hour; 
 allowing 6080 feet in one mile. 
 
 3.1416 
 
 17 diameter 
 
 6080 
 17.5 miles 
 
 219912 
 31416 
 
 30400 
 
 42560 
 6080 
 
 53.4072 
 
 60 one minute 
 
 3204)106400.0(33 revolutions 
 per minute 
 
 3204.4320 
 
 Take the same example to find the numher of 
 miles it will make in 33 revolutions per minute. 
 
 3.1416 
 
 17 diameter wheel 
 
 33 
 
 219912 53.4)6080.0(113 60 one mmute 
 
 31416 534 
 
 113)1980.(17.5 
 
 53.4072 740 113 
 
 534 
 
 • 850 
 
 2060 791 
 
 1602 
 
 590 
 
 17.5 miles per hour 565 
 
 How many miles will a ship travel per hour when 
 the engine is making 80 revolutions per minute, 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 5e3 
 
 pitch of wheel 20 feet, allowing 20 per cent, for slip, 
 allowing 5280 feet in a land mile. 
 
 80 X 60 X 20 
 
 
 80 revolutions 
 60 one hour 
 
 5280 
 
 • 
 
 4800 
 
 20 pitch of wheel 
 
 5280)96000(18.18 
 3.63 
 
 
 18.18 
 
 20 per cent, 
 
 3.6360 
 
 14 . 55 miles the ship makes 
 
 If the pitch of a wheel is 16 feet, how many revo- 
 lutions must it make to advance 10 knots per 
 hour, a knot being 6080 feet? 
 
 6080 X 10 
 16 
 
 6080 one knot 
 10 knots 
 
 38.00 revolutions 
 
 16) 60800 (38 . 00 revolutions 
 48 
 
 128 
 128 
 
54 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 If a ship has a wheel 18 feet pitch, 75 revolutions 
 per minute, allowing 6080 feet in one knot, how many 
 miles will the engine make, and what is the slip of 
 the wheel; observation is 295 miles in 24 hours in 
 one day? 
 
 18 ft. pitch 
 75 revolutions 
 
 90 
 126 
 
 1350 
 
 60 one hour 
 
 81000 
 
 24 one day 
 
 324000 
 162000 
 
 one knot 6080)19440000(319 knots by wheel 
 18240 
 
 319 knots by wheel 
 
 12000 295 observations 
 
 6080 
 
 knots by 3 19) 24. 0000 (7. 52 slip of 
 
 59200 wheel 2233 wheel 
 
 54720 
 
 1670 
 
 1595 
 
 750 
 638 
 
iMARINE AND STATIONARY ENGINEERS CATECHISM 55 
 
 Rule to find how far a steamer will run in six 
 minutes, allowing 1760 yards in a mile, 175 revolu- 
 tions, pitch of wheel 8 feet, not including the slip 
 of the wheel, allowing 3 feet to a yard. 
 
 175 revolutions 
 8 pitch of wheel 
 
 1400 
 
 6 minutes 
 
 one yard 3)8400 feet in 6 minutes (2800 
 6 
 
 — 1760)2800.00(1.59 
 
 24 1760 
 
 24 
 
 10400 
 
 8800 
 
 16000 
 15840 
 
 This boat will run one mile and little over one-half mile in 
 6 minutes. 
 
56 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Rule to find the pitch of a wheel when you know 
 your ship is making 12 knots per hour; to get the 
 pitch of the wheel without taking the ship out of 
 the water, allowing 60 minutes one hour, 15 per cent, 
 off for slip, 120 revolutions, allowing 6080 feet in a 
 mile. 
 
 one hour 60)6080.0(101.3 
 
 60 101.3 
 
 12 knots 
 
 80 
 
 60 2026 
 
 1013 
 
 200 
 
 180 15 off for slip 85)1215.60(143.0 
 . 85 
 
 365 
 340 
 
 256 
 255 
 
 10 
 
 Revolutions 120)143.00(11 .9 pitch of wheel 
 120 
 
 230 
 120 
 
 1100 
 1080 
 
 Pitch of wheel is 11 feet and little over. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 5/ 
 
 To find how many miles this ship makes without 
 any sKp of the wheel allowing 6080 feet in a mile, 
 8 feet pitch of wheel, 90 revolutions per minute. 
 How many miles will this ship make in five days? 
 
 90 revolutions 
 8 pitch of wheel 
 
 720 
 
 60 one hour 
 
 43200 
 
 24 one day 
 
 172800 
 86400 
 
 1036800 
 
 5 days 
 
 6080)5184000.00(852.63 miles ship makes 
 48640 in five days 
 
 32000 
 30400 
 
 16000 
 12160 
 
 38400 
 36480 
 
 19200 
 18240 
 
58 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Rule to find the slip of the wheel when you have 
 an engine counter; the pitch of the wheel 20 feet. 
 The register stands before starting 900, at the finish 
 the register stands 14,000. What is the slip of the 
 wheel? 
 
 14,000 
 900 
 
 13100 
 
 20 pitch of wheel 
 
 262000- number of feet engine makes 
 6080 one knot 
 
 255920 = 100 per cent. 
 
 Number of 
 
 feet engine 262000)255920.00(97 per cent, slip 
 makes 2358000 
 
 2012000 
 1834000 
 
 Pressure on piston: What would be the pressure 
 per square inch on a piston 18 inches in diameter 
 with 100 pounds of steam? 
 
 .7854 18 
 
 324 18 
 
 31416 144 
 
 15708 18 
 
 23562 
 
 324 square inches 
 
 area 254.4696 
 
 100 lbs. steam pressure 
 
 25446. 9600= pressure on piston 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 59 
 
 Engine Counter 
 
 The counter is used on all steam vessels. To 
 find the number of revolutions the engine makes 
 in 10 days, 14 hours, 13 minutes, and 40 seconds. 
 The engine started with 967 revolutions, and after 
 the voyage the register stood 696049. 696049 - 967 
 = 695082, when the engine stopped. Now then 
 
 24 hours one day 
 10 days 
 
 696049 when stopped 
 967 when started 
 
 240 
 14 hours 
 
 254 
 
 60 one hour 
 
 695082 difference when 
 stopped 
 10)40 seconds 
 
 4 
 
 15240 minutes 
 13 minutes 
 
 10)60 seconds 
 
 6 
 6 nurnber of revolutions per minute 
 
 15253.4)695082.00(45.5 
 610136 
 
 849460 
 762670 
 
 1 
 
 867900 
 762670 
 
 
 1052300 
 915204 
 
 
 This engine makes 45.56 revolutions per minute. 
 
60 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Safety Valve 
 
 To find the weight to be placed on a lever safet}" 
 valve: Diameter of valve 4|; steam pressure is 100 
 pounds; fulcrum is 3 inches; length of lever is 30 
 inches; weight of lever is 25 pounds; weight of valve 
 and stem is 9 pounds. 
 
 25 weight of lever 
 
 4.5 diameter 
 
 15 half length 
 
 4.5 
 
 125 
 
 225 
 
 25 9 valve and stem 
 
 180 
 
 3 fulcrum 
 
 
 375 — 
 
 20.25 
 
 27 27 
 
 .7854 
 
 402 8100 
 
 10125 
 16200 
 14175 
 
 15.904350 area of valve 
 100 steam 
 
 1590.435000 
 
 3 fulcrum 
 
 4771.305000 
 402 
 
 Length lever 30)4369.305000(145.64 weight of hall 
 30 
 
 136 
 120 
 
 169 
 150 
 
 193 
 180 
 
 130 
 120 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 61 
 
 Safety Valve 
 
 If a safety valve area is 7 inches, steam pressure 
 is 60 pounds, fulcrum is 3 inches length, lever 24 
 inches long, weight of valve and stem 6 pounds, 
 weight of lever 9 pounds, what would be the weight 
 of the ball to be placed on the end of the lever? 
 
 12 half length of lever 7 area of valve 
 
 9 weight of lever 60 steam pressure 
 
 108 6 valve and stem ' 420 
 18 3 fulcrum 3 fulcrum 
 
 126 18 1260 
 
 126 subtract 
 
 Length lever 24)1134.00(47.25 weight of ball 
 96 
 
 174 
 168 
 
 Work the example back- 60 
 
 ward to find the steam 48 
 
 pressure. 
 
 120 
 7 area 47.25 ball 120 
 3 falcrum 24 lever 
 
 21 18900 
 
 9450 
 
 1134.00 
 126 
 
 21)1260.00(60 steam pressure 
 126 
 
62 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Safety Valve 
 
 We want to find what steam pressure it will take 
 to make a safety valve blow off with a direct 
 weight on top of a valve and stem without any 
 lever; valve is 4 inches in diameter; weight of valve 
 and stem is 12 pounds; the ball weighs 100 pounds. 
 
 ball 100 pounds .7854 
 
 12 valve and stem 16 square of valve 
 
 112 dead weight 47124 
 
 7854 
 
 12 . 5664 area of valve 
 
 12.5664)112.00000(8.91 or nearly 9 pounds of steam 
 1005312 
 
 1146880 
 1130976 
 
 159040 
 125664 
 
 112 dead weight 
 100 steam 
 
 8.91)11200.00(1257.00 
 891 
 
 12.5664)1257.0000(100 weight of ball 
 
 2290 125664 
 
 1782 
 
 5080 
 4455 
 
 3600 
 
 6250 
 6237 
 
 It takes 8 pounds 91 one-hundredths, nearly 9 pounds to 
 raise the valve. Then work it backward to find weight. 
 
IVIARINE AND STATIONARY ENGINEERS CATECHISM 63 
 
 Rule for a Round Tank 
 
 If a tank is 6 feet in diameter what will be the 
 height of the tank to hold 2000 gallons, allowing 
 231 cubic inches to a gallon? 
 
 72 diameter of tank in inches 
 
 72 
 
 144 
 
 504 
 
 
 5184 
 
 .7854 
 
 
 20736 
 25920 
 41472 
 
 36288 
 
 
 231)4071.5136(17.6256 
 231 
 
 1761 
 1617 
 
 17.6256 
 
 12 constant 
 
 352512 
 176256 
 
 1445 
 
 1386 
 
 211.5072 
 
 591 
 
 462 
 
 1293 
 1155 
 
 211)2000.00 gallons(9. 47 
 1899 height 
 
 of tank 
 
 1010 
 844 
 
 1386 
 1386 
 
 1660 
 1477 
 
 Height of this tank is 9.47 nearly 9|. 
 
64 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Round Tank 
 
 To find how many gallons this tank will hold, 
 allowing 231 cubic inches to a gallon. The tank 
 is 28 inches in diameter and 4 feet high. x\lways 
 take the tank in inches when you want to get the 
 
 gallons. 
 
 28 diameter 
 
 28 
 
 224 
 56 
 
 784 
 .7854 
 
 3136 
 3920 
 6272 
 
 5488 
 
 615.7536 area of tank 
 48 height of tank 
 
 49260288 
 24630144 
 
 231)29556. 1728(127.94 number of gallons this tank will 
 231 hold 
 
 645 
 462 
 
 1836 
 1617 
 
 2191 
 2079 
 
 1127 
 924 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 65 
 
 Square Tank 
 
 To find the number of gallons this square tank 
 
 will hold, allowing 231 cubic inches to a gallon. 
 
 Tank is 5 feet 3 inches long, 3 feet 4 inches wide, and 
 
 4 feet deep. 
 
 63 length of tank 
 40 width of tank 
 
 2520 
 48 deep 
 
 20160 
 10080 
 
 231)120960.00(523.63 number of gallons this tanJc 
 1155 will hold 
 
 546 
 462 
 
 840 
 693 
 
 1470 
 1386 
 
 840 
 693 
 
66 INIARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Round Tank 
 
 To find the number of tons of water this tanlv 
 will hold, half full, allowing 32 cubic feet per ton. 
 Diameter of tank is 16 feet, and it is 18 feet high. 
 
 diameter 16 
 
 of tank 16 .7854 
 256 
 
 96 
 
 16 47124 
 
 39270 
 
 256 15708 
 
 half tank 2)201.0624(100 
 2 
 
 • 100 
 
 01 18 height of tank 
 
 800 
 100 
 
 one ton 32)1800.00(56.25 tons 
 160 of water 
 
 200 
 192 
 
 80 
 64 
 
 160 
 160 
 
 This tank will hold fifty-six tons and a quarter. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 67 
 
 Round Tank with Three Dimensions 
 
 To find the number of gallons this tank will hold, 
 allowing 7.48 cubic feet to a gallon, the number of 
 gallons in cubic feet. This tank is 3 feet in diameter 
 at the top, 9 feet high, and 5 feet at the bottom. 
 
 5 - + 3-^ + 5 X 3 = 49 X .7854 = 38.4846 X 9 height of tank 
 3 
 
 3 ft 
 
 .7854 
 49 
 
 70686 
 31416 
 
 38.4846 
 
 9 height 
 
 top 3)346.3614(115.45 
 3 
 
 13 
 12 
 
 16 
 15 
 
 5ft 
 
 115.45 
 
 7 . 48 number of gallons 
 
 in cubic foot 
 
 92360 
 46180 
 80815 
 
 863.5660 
 863 gallons in this tank. 
 
68 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Round Tank to Find the Diameter 
 
 This tank is 4.02 feet high, containing 400 gallons, 
 allowing 6.25 gallons to a cubic foot. 
 
 400 gallons , . ,. 
 
 = 15.9 -^ .7854 = V20.24 = 4.49 ft. in diameter 
 
 4.02 X 6.25 
 
 4.02 height 
 
 6 . 25 gallons to cubic foot 
 
 2010 
 804 
 2412 
 
 gallons 
 
 25. 1250)400.00000(15.900000 
 251250 
 
 .7854) 15.900000(20.24 
 
 1487500 15708 
 1256250 
 
 19200 
 
 2312500 15708 
 2251250 
 
 20.2400(4.49 square root 
 16 
 
 84)424 
 
 336 
 
 8001 
 This tank is 4.49 in diameter nearly 4| feet. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 69 
 
 Flat Bottom Boiler 
 
 To find the number of |-inch stays to put in flat- 
 bottom boiler 18 feet 6 inches long, 12 feet 6 inches 
 wide. The water is 12 feet 10 inches high with 
 45 pounds of steam, allowing 6000 stress on stay. 
 Constant 2.305 in a column of water 1 foot high 
 and 1 inch in diameter. 
 
 222 length of boiler (inches) 
 150 width of boiler 
 
 12)10000(8333 
 96 
 
 11100 
 222 
 
 40 
 36 
 
 33300 
 50.5 total pressure 
 
 40 
 36 
 
 166500 
 166500 
 
 40 
 
 3607)1681650.0(466 number of stays 
 14428 
 
 ■ ■ ■ 875 
 
 
 23885 .875 dec. of | 
 21642 
 
 
 22430 6125 
 21642 7000 
 
 2.305)12.8333(5.5 
 11525 
 
 .765625 
 
 .7854 
 
 13083 
 11525 
 
 3062500 
 3838125 
 6125000 
 5359375 
 
 45 steam 
 5.5 water 
 
 50.5 
 Total pressure 
 
 .6013318750 
 
 6000 stress on 
 
 3607.9912500000 
 
70 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Flat-bottom boiler, to find steam pressure: Boiler 
 is 14 feet 6 inches long, 10 feet 7 inches wide; 65 
 stays one inch and a quarter in diameter. The 
 water in boiler 8 feet high, allowing 6000 stress on 
 stay; constant 2.305. 
 
 174 length of boiler 
 127 width of boiler 
 
 1218 
 348 
 174 
 
 number 65)22098.0(339.9 square inches held up by one 
 stays 195 stay 
 
 259 
 195 
 
 648 
 585 
 
 height of water 
 
 2.305)8.0000(3.4 
 
 6915 
 
 630 
 
 585 
 
 ssure 
 339 
 
 1.25 
 
 1 . 25 diameter of stay 
 
 625 
 250 
 125 
 
 10850 
 9220 
 
 1.5625 
 
 .7854 
 
 21 steam 
 3.4 
 
 24.4 total pre 
 
 62500 
 78125 
 125000 
 109375 
 
 1.22718750 
 
 6000 stress on stay 
 
 
 .9)7363.12500000(21 steam pressure 
 6798 
 
 5651 
 3399 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 To find the working pressure on a round boiler: 
 Single-riveted boiler, allowing 20 per cent, for 
 double-riveted and holes drilled; diameter of 
 boiler, 5 feet 6 inches; thickness of plate, f ; tensile 
 strength, 60,000; factor of safety, J. 
 
 6)60000(10000 
 
 10000 
 
 
 6 
 
 .375 thickness 
 
 
 50000 
 
 
 diameter of boiler 
 
 70000 
 
 
 2)66(33 inches 
 
 30000 
 
 
 6 
 
 
 
 33)3750.000(113.63 
 
 6 
 
 33 
 
 
 6 
 
 
 113.63 
 
 - 
 
 45 
 33 
 
 22.72 
 
 
 136.35 
 
 
 120 
 
 
 
 99 
 
 
 113.63 
 
 
 steam 
 
 .20 
 
 210 
 
 pressure 
 
 
 198 
 
 136 pounds 
 
 
 2272.60 
 
 120 
 99 
 
 
 Calculate the safe-working pressure on a corru- 
 gated furnace, allowing 14,000 as a constant; thick- 
 ness of furnace, i; diameter of furnace, 40 inches. 
 
 40)14000(350 
 120 
 
 200 
 200 
 
 350 
 . 5 thickness 
 
 175.0 
 
 steam pressure 
 
72 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 To find the number of f-inch rivets to hold down 
 a steam dome, smgle-riveted, with 120 pomids of 
 steam; diameter of the dome, 32 inches; f rivet, 
 xf hole; allow 6000 stress on rivet. 
 
 .5184 area of tI hole 
 6000 
 
 3110.4000 
 
 32 diameter 
 32 " 
 
 64 
 96 
 
 1024 
 
 .7854 
 
 3110)96509.9520(31 
 9330 
 
 3209 
 3110 
 
 4096 
 5120 
 8192 
 7168 
 
 804.2496 
 
 120 steam 
 
 160849920 
 8042496 
 
 96509.9520 
 
 It will take 31 rivets, nearly 32 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 73 
 
 To find the diameter of a safety valve to place 
 on a boiler with 75 square feet of grate surface, 
 allowing 3 square feet of grate surface to one inch 
 of area of valve : 
 
 . 7854)25 .000000(31.83 square root Square feet 3)75(25 
 23562 6 
 
 14380 15 
 
 7854 15 
 
 65260 
 
 62832 3 1 . 8300 (5 . 64 diameter of valve 
 
 25 
 
 24280 
 
 23562 106)683 
 
 636 
 
 1124)4700 
 4496 
 
 Diameter of valve 5 . 64 
 " 5.64 
 
 2256 
 3384 
 2820 
 
 31.8096 
 
 .7854 
 
 1272384 
 1590480 
 2544768 
 2226672 
 
 24.98325984 
 
 3 square feet of grate 
 
 74.94977952 
 74 . 94 square feet of grate surface nearly 75 feet. 
 
74 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 What would be the pitch of a stay bolt if the plate 
 was J inch thick, the steam pressure 40 pounds, 
 and thickness of the plate under yg use constant 112, 
 any thickness of plate over i^ up to f , use constant 
 120 squared in 16 of inches? 
 
 120 constant 
 
 
 64 in 16 squared 
 
 480 
 
 
 720 
 
 
 steam pressure 40)7680(192 
 
 
 40 
 
 
 
 1|92 
 
 368 
 
 1 
 
 360 
 
 — 
 
 
 24)92 
 
 80 
 
 96 
 
 80 
 
 — 
 
 square root of 192 
 1|92(14 pitch of stay 
 nearly 14 inches 
 
 Rule to find the thickness of plate in a boiler 
 when you have TS and steam pressure and dia- 
 meter: Diameter of boiler 36 inches, steam pressure 
 is 104 pounds, TS 45,000, factor of safety f. 
 
 
 104 steam 
 
 
 18 half diameter boiler 
 
 6)45000(7500 
 
 
 42 
 
 832 
 
 
 104 
 
 30 
 
 30 
 
 
 7500)1872.0(.25 thickness of the 
 
 — . 
 
 boiler 
 
MARINE AND STATIONARY ENGINEERS CATECHISM /;> 
 
 The stays of a boiler are IJ diameter; the steam 
 
 pressure is 39.27 pounds per square inch; allowing 
 
 5000 stress on stay; find the pitch of the stay. 
 
 1.5 diameter of stay 
 1.5 diameter of stay 
 
 .7854 
 2.25 
 
 75 
 15 
 
 39270 
 15708 
 15708 
 
 2 . 25 square of stay 
 
 1.767150 
 
 5000 stress on stay 
 
 steam 3927)8835.750000(2.25 square root 
 7854 
 2.25(1.5 inches pitch of stay 
 
 9817 1 
 
 7854 
 
 OCMOC 
 
 19635 
 19635 
 
 125 
 
 Take the same example as above: If the pitch of 
 
 stay is 1.5 inches^ the steam pressure is 39.27 pounds 
 
 per square inch. Allowing 5000 stress on stay, what 
 
 would be the diameter of the stay? 
 
 39 . 27 pounds pressure 
 2.25 square of stay 
 
 19635 
 
 7854 
 7854 
 
 steam 39.27)88.3575(2.25 
 7854 
 2.25(1.5 diameter stay 
 
 9817 1 
 
 7854 ' 
 
 25)125 
 
 19635 125 
 
 19635 
 
76 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 A triple-riveted Scotch boiler, 4 rows of rivets 
 in one shear; jf hole; pitch of double rows of rivets 
 3f ; single pitch TJ; the diameter of the boiler is 72 
 inches; thickness of plate, f ; tensile strength 55,000, 
 allowing 40,000 for iron rivet; factor of safety 3-; 
 but straps the same thickness as the shell of boiler. 
 
 . 6903 area of H hole 
 40000 iron rivet 
 
 27612.0000 
 This is what the rivet will stand 
 
 40000 shearing of the rivet 
 ,85 per cent. 
 
 200000 
 320000 
 
 34000.00 
 
 40000 shearing of the rivet 
 
 74000 . 00 shearing of all rivets 
 
 Shearing of all of the rivets by taking 85 per cent, 
 of the single rivet and adding the single to it gives 
 the shearing of all rivets 74,000. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 77 
 
 Triple-Riveted 
 
 7 . 25 long pitch 
 . 5 thickness 
 
 7 . 250 long pitch 
 . 9375 decimal of i| hole 
 
 3625 
 
 55000 TS 
 
 6.3125 
 
 . 5 thickness 
 
 18125000 
 18125 
 
 315625 
 
 55000 TS 
 
 199.375000 
 constant 
 
 1578125000 
 1578125 
 
 199)1735.9375000(87 per cent, plate section 
 2)72(36 .87 per cent. 
 
 36 
 5 
 
 180 
 
 .5 
 
 435 
 ' 55000 TS 
 
 2175000 
 2175 
 
 ;6903 area it hole 
 , 4 rows of rivets 
 
 180)23925.000(132.8 
 180 
 
 592 
 540 
 
 .27612 
 
 74000 shearing of all rivets 
 
 110448000 
 193284 
 
 20432.88000 
 
 2761 . 20000 single rivet added 
 
 525 
 
 360 constant 199)23194.08000(116 rivet shearing 
 
 199 
 
 1650 
 
 1440 329 
 
 199 
 
 constant 
 
 1304 
 1194 
 
 132 . 8 pounds of steam on this boiler. 
 
78 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 To find the diameter of any stay with any given 
 pressure: We will take 7500 pounds pressure per 
 square inch. Allowing 6000 stress on stay, find 
 diameter. Always use .7854 X 6000, gives what a 
 one inch stay will hold, and divide that into the 
 pressure and extract the square root of the answer 
 = diameter of stay. 
 
 .7854 
 6000 
 
 pressure 
 4712)7500.00(1.59 
 4712 
 
 
 4712.4000 
 
 27880 
 23560 
 
 1.5900(1.26 
 1 
 
 diameter stay 
 
 22)59 1| 
 44 
 
 
 43200 
 42408 
 
 
 
 246)1500 
 1476 
 
 If the stay in a boiler is pitched 6X6 from centre 
 
 to centre with 120 pounds pressure per square inch, 
 
 what pressure is on the stay or what pressure is the 
 
 stay holding up? 
 
 6 pitch 
 
 36 
 
 120 steam 
 
 720 
 36 
 
 This stay is holding 43 . 20 pounds 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 79 
 
 To find the working pressure of steam you would 
 allow on a 1| round stay, allowing 6000 stress on 
 stay; pitch of stay 6X6 from centre to centre. 
 
 1 . 5 diameter stay . 7854 
 
 1.5 2 . 25 square of stay 
 
 75 39270 
 
 15 15708 
 
 2.25 
 
 6 
 
 15708 
 
 1.767150 
 
 6000 stress on stay 
 
 6 36) 10602 . 900000(294 steam pressure on stay 
 — 72 
 36 
 
 340 
 
 324 
 
 162 
 144 
 
 To find the working pressure per square inch 
 you would allow 1 J square stay, allowing 6000 stress 
 on stay; pitch of stay 6X6 from centre to centre. 
 
 1.5 
 1.5 
 
 75 
 15 
 
 2.25 
 6000 
 
 square of pitch 36)13500.00(375 pounds steam pressure. 
 
80 MAKINE AND STATIONARY ENGINEERS CATECHISM 
 
 To find the diameter of any stay to hold up any 
 pressure when you have the steam pressure and the 
 pitch of the stay. Now we will take, for example: 
 The pitch of stay is 8 X 8 inches pitch from centre to 
 centre and steam pressure per square is 160 pounds. 
 What is the diameter of the stay? Always use 
 .7854 X 6000 stress on stay. 
 
 .7854 8 pitch 
 
 6000 8 
 
 4712.4000 64 square of the pitch 
 
 160 steam pressure 
 
 3840 
 64 
 
 4712)10240(2.17 pressure per square inch 
 
 square root 
 
 2.17(1.47 diameter of stay 
 1 
 
 24)117 
 96 
 
 287)2100 
 1909 
 
 It will take 1| stay to hold this pressure. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 81 
 
 Rule to find : If there were a number of stays in a 
 flat surface, and if one was to give way, what extra 
 pressure would it throw on the other stays in the 
 boiler? The stays are 12 X 12 centre to centre; the 
 stay is If inches in diameter; steam pressure is 70 
 pounds. What extra strain will be put on the other 
 stays, allowing J the pressure after the stay gave 
 
 awayr 
 
 12 
 
 12 pitch 
 
 24 
 12 
 
 144 
 70 steam 
 
 1.625 
 
 1 . 625 diameter of stay 
 
 10080 strain before broke 
 
 8125 
 3250 
 9750 
 1625 
 
 2.640625 
 
 .7854 
 
 10562600 
 13203125 
 21125000 
 
 18484375 
 
 area of stay 2.0739468850 
 
 2.073)10080.0000(4862.4 after stay broke 
 3)4862.4(1620.8 8292 
 
 3 
 
 18 
 18 
 
 6 
 6 
 
 24 
 24 
 
 17880 
 16584 
 
 1620.8 
 after broke 4862.4 
 
 12960 
 12438 
 
 6483.2 
 
 strain thrown 
 
 on stays 
 
 5220 
 4146 
 
 10740 
 8292 
 
 
82 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 To find the number of square inches over the top 
 of the tubes in the boiler: height, 12 inches; cord, 
 48 inches; take f cord. 
 
 48 
 2 the cord 
 
 3)96(32 
 9 
 
 32 
 
 12 height 
 
 64 
 32 
 
 I of cord 384 
 
 18 one-third cord 
 
 402 square inches in this 402 
 space over tubes 
 
 12 height 
 12 
 
 24 
 12 
 
 144 
 
 12 height 
 
 288 
 144 
 
 twice the cord 96)1728(18 one third of cord 
 96 
 
 768 
 
 768 
 
 402 square inches in this space over the tubes. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 83 
 
 To find the working pressure of a straight furnace 
 44 inches in diameter, 48 inches long, thickness of 
 plate i inch, using a constant 51.5 — 10.3 — 18.75 
 
 YT) times the pressui'e 
 
 on con vexed heads is 18.75 constant 
 
 pressure on concaved .8 = j o 
 
 head 
 
 150.00 
 49.44 
 
 constant 
 diameter 44)51.50(1.17 
 44 
 
 100.56 
 1.17 
 
 70392 
 10056 
 10056 
 
 steam pressure 117.6552 
 
 75 
 
 44 
 
 310 
 308 
 
 1.03 constant 
 48 
 
 824 
 412 
 
 49.44 
 
 Required the working pressure on convex heads, 
 concave heads, radius 52 inches, TS 60,000, thickness 
 of plate J, factor of safety ^. 
 
 5)60,000(12,000 
 5 
 
 10 
 10 
 
 12,000 
 
 .5 thickness 
 
 half radius 26)6000.0(230 
 52 
 
 80 
 
 78 
 
 230 
 
 .8 
 
 184.0 
 
 20 
 
 230 pounds on convexed head. 
 184 pounds on concave head. 
 
84 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 The correct rule to find the workmg pressure on 
 any boiler and percentage of the plate compared 
 to the solid part of the boiler and the rivet shear: 
 
 Pitch of rivet 2|, hole or rivet xf^ thickness of 
 plate I, two rows of rivets, TS 50,000, diameter 
 of boiler 60 inches, factor of safety ^, allowing 45,000 
 for steel rivet. 
 
 2 . 75 pitch of rivet 2 . 7500 pitch 
 
 .375 thickness of plate .8125 decimal xf 
 
 1375 2.75)1 .9375(70 percentage of plate 
 
 1925 1925 
 
 825 
 
 125 
 
 103.125 
 
 constant area of if hole .51849 
 
 . 2 rows of rivets 
 
 constant 103)10369.8(100 
 30 
 6 . 70 per cent. 100 
 
 .375 45000 steel rivet 
 
 180 
 
 350 500000 
 
 490 400 
 
 210 
 
 TS 50000)4500 . 000(90 rivet 
 
 . 26250 450 shear) 
 
 50000 TS 
 
 180)13125.00000(72 steam pressure 
 1260 
 
 525 
 360 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 85 
 
 To find the tensile strength of a boiler, single- 
 riveted, with holes drilled; steam pressure 125 
 pounds, diameter of boiler 40 inches, thickness of 
 plate J inch, factor of safety J. 
 
 125 steam 
 6 factor safety 
 
 750 
 
 20 haK diameter boiler 
 
 thickness .25)15000.00(60000 TS of plate 
 150 
 
 To find the diameter of the same boiler as above: 
 TS 60.000, thickness of plate J, steam pressure 125 
 pounds, factor of safety |. 
 
 steam 125 
 
 6 safety 
 
 60000 TS 
 .25 thickness 
 
 750 
 
 300000 
 120000 
 
 
 750)15000.00(20 
 1500 
 20 
 
 2 always twice 
 
 40 diameter of boiler 
 Diameter of boiler is 40 inches. 
 
86 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 The rule for bracing the head of a boiler above 
 the tubes: 
 
 For example, will say that we have to brace in this 
 boiler 353.77 square inches, the load to be carried 
 by the braces will be equal to the area multiplied by 
 the working pressure, which is 130 pounds per square 
 inch: total load, 353.77 X 130 = 45,990 pounds. No 
 boiler brace should be allowed greater stress than 
 6000 pounds per square inch. The number of braces 
 required may be found by dividing the total load by 
 what one brace will stand, which in this case is 
 45,990-^6000 = 7.66, say 8 braces having an area of 
 one inch square, which corresponds to about 1| 
 inches in diameter. The surface or area supported 
 by each brace is found by dividing the area to be 
 supported by the number of braces, which gives 
 353.77 ^ 8 = 44.22 square inches; the square root 
 of this number will give the distance between the 
 braces or the pitch which is 6.64 inches or 6{^. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 87 
 
 Example for bracing the head of the boiler: 
 
 353 . 77 square inches 
 130 steam 
 
 1061310 
 35377 
 
 one brace 6,000)45990.10(7.66 number of stays— will say 8 
 42000 
 
 39901 stays 8)353 . 77(44 . 22 
 
 36000 
 
 39010 
 36000 
 
 square 
 
 root 44.2200(6.64 
 
 36 inches held 
 
 up by one 
 
 126)822 stav 
 
 756 
 
 32 
 
 33 
 32 
 
 inches held up by 
 one stay 
 
 17 
 16 
 
 17 
 16 
 
 1324)6600 
 5296 
 
 6 . 64 square inches held up by one stay. In other words, 
 6.64 is pitch of stay. 
 
88 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 The quickest way to get the horse-power of a 
 boiler is to get the number of square feet of the 
 grate surface. We will say that we have got 50 
 square inches of grate surface, multiplied by 50, 
 multiplied by constant of 45, allowing 14 square 
 feet to a horse-power. Example: 
 
 50 
 50 
 
 2500 
 
 45 constant 
 
 
 12500 
 10000 
 
 
 one square ft. 144)112500.0(781.2 
 1008 
 
 1170 
 1152 
 
 14)781.2(55.8 horse 
 70 power of 
 boiler 
 
 81 
 
 70 
 
 112 
 112 
 
 180 
 144 
 
 360 
 
 288 
 
 This boiler has 55 . 8 horse-power. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 89 
 
 Rule to find the correct pitch of rivets in a single- 
 riveted seam of a boiler : If the thickness of the plate 
 is f , and the tensile strength is 60,000, the rivet 
 J, the hole is yf , the shearing strength of the rivet 
 is 40,000, then proceed. The area of jf hole is 
 .6903 X 40,000, gives you the strength of the rivet, 
 which is 27612.0000 ^ by f X 60,000 = 22500 and 
 27612.0000 ^ 22500 = 1.2272; nearly li add the 
 diameter of the hole: IJ + tI = 2j^ pitch. 
 
 .6903 area of if hole 
 40000 rivet 
 
 27612.0000 strength of rivet 
 
 22500)27612.0000(1.2272 nearly li pitch 
 22500 
 
 1.25 
 
 dec. of if .9375 51120 
 45000 
 
 2.1875 = 2^ 
 
 pitch 61200 
 
 45000 
 
 162000 
 157500 
 
 45000 
 45000 
 
90 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Rule to find the correct pitch of double-staggered 
 riveted lap-joint where the plates are made of 
 steel f of an inch thick ; tensile strength of the plate 
 is 55,000, the diameter of rivet is J, the diameter of 
 hole is X6 J allowing 40,000 pounds shearing strength 
 for rivet; two rows of rivets. 
 
 .375 thickness | 
 55,000 TS .6903 = area of M hole 
 
 2 rows of rivets 
 
 1875000 
 
 1875 13806 
 
 40,000 shearing of rivet 
 
 20625.000 
 
 20625 . 000)55224 . 0000(2 . 6775 
 41250 
 
 2.6775 
 
 139740 .9375dec. of H 
 123750 
 
 3.6150 = 3i^ 
 
 159900 pitch of rivet 
 ] 44375 
 
 155250 
 144375 
 
 108750 
 103125 
 
 Pitch of this rivet is Sye. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 91 
 
 Rule to find the coal burned per hour by indicated 
 horse-power : Diameter of cylinder 42 inches, 48-inch 
 stroke, 65 revolutions per minute, the diagram 
 showing 55.6 pounds mean effective pressure on 
 piston, consuming 30 tons of coal per day. Cal- 
 culate the indicated horse-power developed and the 
 consumption of coal per hour indicated horse-power. 
 
 stroke 48 
 
 2 twice 
 
 96 
 
 65 revolutions 
 
 480 
 576 
 
 12)6240(520 
 60 
 
 24 
 24 
 
 .7854 
 1764 cylinder squared 
 
 31416 
 47124 
 
 54978 
 
 7854 
 
 1385.4456 
 
 55 . 6 mean effective pressure 
 
 83126736 
 
 69272280 
 69272280 
 
 77030.77536 
 
 520 feet per minute 
 
 154061550720 
 38515387680 
 
 33)40056.00318720(1213 . 8 horse-power 
 33 
 
 2240 
 30 
 one 
 
 day 24)67200(2800 
 
 48 
 
 192 
 192 
 
 70 
 66 
 
 45 
 33 
 
 126 
 99 
 
 270 
 264 
 
 1213.8)2800.000(2.31 pounds 
 24276 per hour 
 
 per horse- 
 power 
 
 37240 
 36404 
 
 18460 
 12138 
 
92 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Rule to find the working pressure of steam you 
 would allow on a straight furnace per square inch: 
 diameter 44 inches, length 48 inches, thickness of 
 furnace i, using three constants. 
 
 Constants: . diameter 44)51 . 5(1 . 17 
 
 51.5 44 
 
 18.75 
 
 1.03 18.75 75 
 
 .8 = * 44 
 
 150.00 310 
 
 49.44 308 
 
 100.56 
 1.17 
 
 1.03 
 
 70392 48 length 
 
 10056 
 
 10056 824 
 412 
 
 117.6552 
 Steam pressure is 117 pounds. 
 
 49.44 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 93 
 
 The correct way to find the Uft of a valve. We 
 will take a three-inch valve: 
 
 3 in, valve 
 3 in. valve 
 
 .7854 
 
 9 square of valve 
 
 9 
 
 9.4248)7.068600(.75 = f lift of valve 
 659736 
 
 471240 
 constant 3.1416 471240 
 
 
 
 9.4248 of 
 
 valve 
 
 There is another way to get the lift of the valve 
 by dividing by J the diameter of the valve. Take 
 the same valve as above, 3 inches in diameter : 
 
 4)3.00(.75 = f 
 
 28 
 
 20 
 20 
 
 If you had one ton of coal and 300 pounds of 
 ashes, what percentage of ashes would you have? 
 
 Example : 
 
 300 ashes 
 100 per cent. 
 
 one ton 2240)30000.00(13.39 percentage of ashes 
 2240 
 
 7600 
 6720 
 
 8800 
 6622 
 
 21800 
 20160 
 
94 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Coal Bunker 
 
 To find how many tons of coal this bunker will hold, 
 allowing 40 cubic feet per ton. We will take this 
 bunker in inches when you cannot get it in feet. 
 Where you have three dimensions in feet, multiply 
 the three dimensions in feet and you have cubic 
 feet; where you cannot get it in feet, take it in 
 inches and proceed this way: 
 
 Length 18 ft 6 in. 
 
 222 length in inches 
 
 Depth 10 ft. 4 in. 
 
 124 depth in inches 
 
 Width 6 ft. 3 in. 
 
 
 
 888 
 
 
 444 
 
 
 222 
 
 
 27528 
 
 
 75 width in inches 
 
 137640 
 192696 
 
 one cubic foot 1728)2064600(1194.00 
 1728 
 
 40)1194.00(29.85 
 
 3366 80 tons 
 
 1728 — 
 
 . 394 
 
 16380 360 
 
 15552 
 
 340 
 
 8280 320 
 
 6912 
 
 200 
 
 200 
 
 This bunker will hold 29.85 tons. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 95 
 
 Coal Bunker 
 
 To find the third dimension of a coal bunker to 
 hold 40 tons of coal, allowing 42 cubic feet per ton. 
 depth of bunker is 15 feet 6 inches, width of bunker 
 is 12 feet G inches: 
 
 186 depth 
 150 width 
 
 9300 
 186 
 
 one square foot 144)27900.00(193.75 
 144 
 
 1350 
 1296 
 
 540 
 432 
 
 1080 42 cubic feet 
 
 1008 40 tons 
 
 720 193.75)1680.0000(8.67 
 720 155000 length 
 
 — - of 
 
 130000 bunker 
 116250 
 
 137500 
 135625 
 
 Length of this bunker is 8.67. 
 
 Take page 96; you will find the bunker is figured 
 in feet instead of inches. 
 
96 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Coal Bunker 
 
 Take the same bunker as page 95. This bunker 
 is done in feet to show you how to figure it in inches 
 when you cannot get it in feet: Depth of bunker 15 
 feet 6 inches, width 12 feet 6 inches, to hold 40 tons 
 of coal, allowing 42 cubic feet per ton: 
 
 15.5 depth 
 12.5 width 
 
 775 
 310 
 155 
 
 . 
 
 193.75 
 
 42 cubic feet 
 40 tons 
 
 
 193 . 75) 1680 . 0000(8 . 67 length 
 155000 
 
 
 130000 
 116250 
 
 
 137500 
 135625 
 
 Length of this bunker is 8.67. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 9- 
 
 Coal Bunker 
 
 To find the average width of a coal bunker: 
 Length of bunker, 45 feet; deptli of bunker, 16 feet; 
 top of bunker, 25 feet; middle of bunker, 18 feet; 
 bottom of bunker, 10 feet. Always divide by 6.. 
 
 25 top of bunker 
 72 four times middle 
 10 bottom 
 
 6)107.00(17.83 average width nearly IS feet 
 
 47 
 42 
 
 50 
 
 48 
 
 20 
 
 18 
 
 Coal Bunker 
 
 To find the average width: Top 10 feet, bottom 5 
 feet. Always divide by 2 to get average width. 
 
 10 top 
 5 bottom 
 
 Average width 7§ 2) 15.0(7 . 5 
 
 14 
 
 10 
 
98 MAKINE AND STATIONARY ENGINEERS CATECHISM 
 
 Rule to balance weight on end of a lever; this 
 lever has a weight of 154 pounds on the long end; 
 the long arm is 34 J inches; the short arm is 15 J 
 inches; what weight will it take on the short arm 
 to balance the weight (154 pounds) on the long arm? 
 
 154 
 
 4^ 
 
 34 1-2 IN. 
 
 n 15 
 
 154 weight on long arm 
 34.5 length of long arm 
 
 770 
 616 
 462 
 
 short arm 15.5)5313.0(342 weight of ball on short arm 
 465 
 
 663 
 620 
 
 430 
 310 
 
 It will take a weight 342 pounds to balance the lever. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 99 
 
 To find the stroke of an air pump when you have 
 the dimensions of the air pump beam and the 
 stroke of the engine. We will say the stroke of 
 the engine is 3 feet, the length of the air pump 
 beam is 5 feet over all, the long arm is 3 feet, and 
 the short arm is 2 feet. 
 
 < 3 FT 
 
 O ^__ 2 
 
 5 FT. 
 
 This example is done in two ways; one way in feet and the 
 other in inches. 
 
 3 stroke of engine 
 2 short arm 
 
 Long arm 3)6(2 stroke of air pump 2 feet 
 6 
 
 36 stroke of engine 
 24 short arm 
 
 144 
 
 72 
 
 Long arm 36)864(24 stroke of air pump 24 inches 
 
 72 
 
 144 
 144 
 
100 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 To Point Off an Indicator Card 
 
 STEAM LINE 
 
 CURVE 
 
 EXHAUST LINE 
 
 The correct way to get the mean effective pressure 
 on the piston is to lay your card out in 10 equal 
 parts; each one of the lines denotes pounds of 
 steam; take your scale, measure the length of each 
 line, put it down on paper, then count it up; then 
 multiply by the spring you use and divide by the 
 10 spaces on your card; that will give you the mean 
 effective pressure. 
 
 Rule to Find the Pressure on a Piston. 
 
 If the pressure of steam on the piston is 70 pounds 
 when the engine is working full speed at 62 revolu- 
 tions, and the speed becomes reduced to 50 revolu- 
 tions, what would the steam pressure be? 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 101 
 
 revolutions 62 
 62 
 
 124 
 372 
 
 3844 
 
 70 steam pressure 
 50 revolutions reduced 
 
 3500 
 
 50 reduced revolutions 
 
 3844)175000.00(45.52 reduced steam press- 
 15376 ure 
 
 21240 
 19220 
 
 20200 
 19220 
 
 9800 
 7688 
 
 To find the total pressure on a shaft either in 
 pounds or tons: Mean effective pressure is 100 
 pounds, the area of the piston is 350, stroke of the 
 engine 24 inches, pitch of wheel 8 feet, revolutions 
 of engine are 90 per minute. 
 
 90 revolutions 
 4 stroke 
 
 360 feet per minute 
 
 90 revolutions 
 8 pitch of wheel 
 
 720 
 
 . 350 area of piston 
 
 100 mean effective pressure 
 
 35000 
 
 360 feet per minute 
 
 2100000 
 105000 
 
 720)12600.000(17500 pounds 
 720 
 
 5400 2240)17500.00(7.81 tons 
 5040 15680 
 
 3600 
 3600 
 
 18200 
 17920 
 
 2800 
 2240 
 
102 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 To find the thickness of a corrugated furnace, and 
 find the diameter of the furnace: Steam pressure is 
 175, diameter of furnace 40 inches, thickness of 
 the furnace is J, constant 14,000. 
 
 14000 constant 
 . 5 thickness 
 
 175 steam 
 
 40 diameter steam 175)7000.0(40 diameter 
 700 
 
 14000)7000 . 0) . 5 thickness 
 70000 
 
 To find the weight of a safety-valve weight that 
 is round: Get the diameter of the ball, then square 
 it, then cube it, multiply it by a constant of 9, then 
 divide it by a constant 64. 
 
 7 diameter ball 
 7 diameter ball 
 
 49 
 7 cube it 
 
 343 
 
 9 constant 
 
 constant 64)3087.0(48.2 weight of ball 
 256 
 
 527 
 512 
 
 150 
 128 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 10)^ 
 
 p To find the area of any diameter without using 
 .7854. We will take 5 inches in diameter; first square 
 it, then multiply it by .77, then multiply your 
 answer by 2 twice; keep one figure to the right 
 
 twice. 
 
 .7854 5 diameter 
 
 .25 5 diameter 
 
 39270 25 
 
 15708 .77 
 
 19.6350 area 175 
 
 175 
 350 
 350 
 
 19.6350 area 
 
 Example: To find the diameter of a shaft and to 
 find the diameter of the steam pipe of a compound 
 engine: High-pressure cylinder is 13 inches in diam- 
 eter, low pressure cylinder is 27 inches in diameter, 
 one-fifth of the low pressure cylinder is the diam- 
 eter of the shaft; and one-quarter the diameter of 
 the shaft subtracted from the diameter of the shaft 
 is the diameter of the steam pipe. 
 
 l.p. e. 
 
 
 5)27.0(5.40 diameter of shaft 
 
 25 
 
 
 — 
 
 4)5.40(13.5 one-quarter of shaft 
 
 20 
 
 4 
 
 20 
 
 — 
 
 — 
 
 14 
 
 
 12 
 
 
 20 5 . 40 diameter of shaft 
 
 
 20 1 . 35 one-quarter of shaft 
 
 4 . 05 diameter of steam pipe 
 
 The diameter of the steam pipe is 4.05, and the diameter of 
 the shaft is 5.4. 
 
104 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Example: To find the diameter of a steam pipe 
 when you have the horse-power of the engine, using 
 a constant of 6; we will say the horse-powder is 150. 
 
 6)150(25 
 12 
 
 25(5 diameter of steam pip e 5 inches 
 
 30 25 
 30 — 
 
 Example: To find how many times the steam 
 expands .in compound engine and triple-expansion 
 engine: Steam pressure 69 pounds, atmospheric 
 pressure 15 pounds, 12 pounds pressure on the 
 low-pressure cylinder. 
 
 69 steam pressure 
 
 15 atmospheric pressure 
 
 pressure on low 12)84(7 steam expands 7 times 
 84 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 105 
 
 Example: A blow-ofi' cock on the bottom is 14 
 feet below the sea level and 9 feet below the water 
 level in the boiler. What pressure per square inch 
 would be required to blow the water out of the 
 boiler? 
 
 14-9 
 
 14 
 
 2.305 
 
 9 
 
 
 2.305)5.00000(2.16 
 4.610 
 
 
 3900 
 
 2305 2 pounds — nearly 3 pounds. 
 
 
 15950 
 13830 
 
 Example: To find the number of gallons of oil 
 a barrel will hold, allowing 231 cubic inches in 
 United States gallon: Take the largest part of the 
 middle of the barrel and get the area of it, then 
 multiply by the length in inches, then divide by 
 231 = number of gallons; diameter of barrel 18 
 inches, length 36 inches. 
 
 18 X 18 X .7854 X 36 „ 
 231 = -^^^^"' 
 
106 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 The Question is Sometimes Asked: What 
 IS Steel? 
 
 Steel is iron with a mixture of carbon or an alloy 
 of iron, the alloy being principally carbon steel. 
 Steel can be melted like cast iron and welded like 
 wrought iron. There are hard and soft steels, 
 according to the process of production and proportibn 
 of alloy. 
 
 The Question is Sometimes Asked: What is 
 Alloy? 
 
 Alloy is a mixture or compound of two or more 
 metals. Two parts of tin and six parts of lead is 
 an alloy suitable for fusible plugs, and which melts 
 at 380° Fahrenheit. An alloy is used to reduce 
 the quality of one of the parts. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 10< 
 
 Rule to Find Size of a Cylinder 
 
 Rule to find the size tliat a cylinder should be 
 in diameter: In the example we have 151 tons on 
 piston and 64 pounds of steam on piston; then mul- 
 tiply 15i by 2240 pounds in one ton, then divide by 
 the steam pressure, then divide by .7854, then get 
 the square root of the answer, and that will give you 
 the diameter of cylinder. 
 
 15 . 25 tons on piston 
 2240 one ton 
 
 61000 
 3050 
 3050 
 
 Steam, pressure 64)34160.00(533.75 
 
 320 
 
 Constant .7854)533.7500(679 
 
 216 47124 
 
 192 
 
 62510 
 
 240 54978 
 
 192 
 
 75320 
 
 480 70686 
 448 
 
 320 
 320 
 
 6|79(26 diameter of cylinder 
 4 
 
 46)279 
 276 
 
 Diameter of cylinder is 26 inches. 
 
108 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Rule to get the area of any diameter : First square 
 the diameter, then multiply by .7854 = the area. 
 Now to find the diameter : Divide the area by .7854, 
 then get the square root of the answer = diameter. 
 We will take a 10-inch valve. 
 
 10 diameter 
 10 .7854 
 
 100 
 
 100 
 
 78.5400 area of 10 
 .7854)78.5400(100 
 7854 
 
 1 1 00 (10 diameter of 
 1 valve 
 
 2)000 
 
 Rule to find the horse-power of your dynamo: 
 Multiply your volt meter by your amperes, and 
 divide by 746 watts, will give you the horse-power 
 of your dynamo; 746 watts equal one horse-power. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 109 
 
 Rule to Find the Speed of a Wheel. 
 
 Rule to find the speed which a wheel on a station- 
 ary engine has to make to comply with the law; the 
 limit speed is 6000 revolutions in feet per minute. 
 We will take a wheel 10 feet in diameter; revolu- 
 tions per minute are 125. 
 
 3.1416 
 
 10 diameter of wheel 
 
 31.4160 
 
 125 revolutions 
 
 1570800 
 628320 
 314160 
 
 feet per minute 3927.0000 this will make 3927 feet per minute. 
 
 Rule to get the area of any stay under one inch: 
 
 We will take J stay; we will get the area the quickest 
 
 way. 
 
 .7854 
 
 8 49 square the seven 7 
 
 8 7 
 
 — 70686 — 
 
 64 31416 49 
 
 64)38.4S46(.6013 area of | stay 
 384 
 
 84 
 64 
 
 206 
 192 
 
110 'MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Rule to find the inside diameter of a cylinder 
 
 with 22 bolts in cylinder head six and a half inches 
 
 apart, allowing 2| inches on each side of cylinder 
 
 head to be taken off; constant 3.1416. 
 
 22 number of both 
 6 . 5 apart 
 
 110 
 132 
 
 3.1416)143.00000(45.5 
 125664 
 
 45.5 
 
 173460 ' 5. off of each side 
 151780 
 
 40.5 
 
 162800 diameter of cyhnder 40 . 5 
 
 157080 
 
 Rule to find how many pounds of coal and how 
 
 many tons of coal a boiler will burn in 24 hours, 
 
 allowing 2000 pounds to a ton, with 75 square feet 
 
 of grate surface, 15 pounds of coal to square foot of 
 
 grate. 
 
 75 grate 
 
 15 pounds square foot 
 
 375 
 75 
 
 1125 
 24 one day 
 
 4500 
 2250 
 
 2000)27000.0(13.5 tons in 24 hours 
 2000 
 
 7000 
 6000 
 
 10000 
 10000 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 111 
 
 Rule to jSnd how many bolts, 1 J inches in diameter, 
 are required for a cylinder cover 56 inches in diam- 
 eter, the steam pressure being 90 pounds per 
 square inch, the working strain on the bolts not 
 to exceed 2000 pounds per square inch. 
 
 56 X 56 X .7854 X 90 
 1.5 X 1.5 X .7854 X 2000^ 
 
 56 diameter of cylinder 
 56 
 
 62 bolts, say 63 bolts 
 
 336 
 
 280 
 
 1 . 5 diameter of bolt 
 1.5 
 
 3136 
 
 .7854 
 
 12544 
 15680 
 25088 
 21952 
 
 75 
 15 
 
 225 
 
 2463.0144 
 
 90 steam 
 
 221671.2960 
 
 3534)221671 . 0(62 . 7 nearly 63 
 21204 bolts 
 
 .7854 
 2.25 square feet 
 
 39270 
 15708 
 15708 
 
 1.767150 
 
 2000 
 
 3534.300000 
 
 9631 
 7068 
 
 25630 
 
 24738 
 
112 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Rule to find the number of bolts, when the diameter 
 of the bolt and the pitch are given; may be found 
 by the following rule: The diameter of the cylinder 
 cover is 33 inches, the centre of the bolts from 
 edge of cylinder is IJ inches from edge, the pitch 
 of the bolts is SJ inches. How many bolts will be 
 required in cylinder cover? 
 
 33 — (1| X 2) = 30 diameter of cover. 
 
 30 X 3.1416 
 
 3.25 pitch of bolt 
 1.5 33 
 
 2 3.0 
 
 3.0 30 . diameter of cover 
 
 3.1416 
 
 30 diameter of cover 
 
 pitch 3.25)94.248.0(28.9 number of bolts, say 29 holts 
 650 
 
 2924 
 2600 
 
 3248 
 2925 
 
 It will take 29 bolts in this cylinder cover. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 113 
 
 Rule to find the indicated horse-power required 
 to exert a given thrust or power on a thrust 
 block may be found by the following example: 
 What indicated horse-power would be required to 
 exert a force or thrust of 27,500 pounds on a thrust 
 block with a screw propeller of 20 feet pitch, making 
 60 revolutions per minute, allowing 33,000 one 
 horse-power if the slip be 10 per cent.? 
 
 27500 X 20 pitch X 60 rev. ,„„„ , 
 
 ^ = 1000 horse-power 
 
 oo,00U 
 
 1000 X 10 slip ,__ , , ^, ^ „ 
 -^ = 100 horse-power and the power actually 
 
 employed will be 1000 — 100 = 900 horse-power 
 The horse-power would be 900. 
 
114 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Rule to find the pressure per square inch of 
 steam on a piston by the indicated horse-power of 
 an engine. Indicated horse-power of an engine is 
 180, the diameter of the cyKnder is 17 inches, 
 length of stroke is 2 feet, and the number of revolu- 
 tions per minute are 80. What is the pressure on 
 the piston per pound per square inch? 
 
 17 diameter of cylinder 
 17 diameter of cylinder 
 
 180 horse-power ■ 
 
 33000 119 
 17 
 
 
 540000 -— 
 540 289 
 
 7854 
 
 2 stroke 
 2 stroke 
 
 4 
 
 80 revolutions 
 
 320 
 
 72633)5940000(81 . 7 pounds 
 
 581064 1156 
 1445 
 
 129360 2312 
 72633 2023 
 
 567270 226.9806 
 508431 320 stro] 
 
 ke in feet 
 
 45396120 
 6809418 
 
 
 72633.7920 
 Pressure per square inch on piston is 81 . 7. 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 115 
 
 Rule to find the required time to pump a given 
 quantity of water, when two or more pumps of 
 different sizes are employed to empty a tank, may 
 be found by the following example: Divide the 
 product of the time in which each pump will sepa- 
 rately empty the tank by the sum of the time 
 required by each pump to separately empty the 
 tank. The water-ballast pump will empty a tank 
 in 3 hours, and the boiler pump will empty it in 
 10 hours. In what time can the tank be emptied by 
 both pumps working together? 
 
 ^ „ = 2 hours and 18 minutes. 
 
 13)30(2 hours and 18 minutes takes to empty 
 26 tank 
 
 4 
 
 60 one hour 
 
 13)240(18 minutes 
 13 
 
 110 
 104 
 
116 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 An evaporator is a vessel in the form of a vertical 
 boiler in which there are two manifolds connected 
 together by a number of copper pipe-coils. The 
 upper manifold is connected to the auxiliary steam 
 line, the bottom manifold is connected to a steam 
 trap and to the condenser, the evaporator is partly 
 filled with water, and live steam is admitted to the 
 upper manifold and passes through the coils and 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 117 
 
 bottom manifold and into the steam trap; the hot 
 steam in the coils evaporates the surrounding water 
 into steam and is then allowed to pass into the con- 
 denser through a pipe connected at the top of the 
 evaporator, and, after being condensed, is used as 
 fresh water, to put in the main boilers. 
 
 Rule to Find the Horse-power. 
 
 Rule to find the horse-power it will take to run 
 a number of incandescent electric lights 16 candle 
 power, allowing 3 J watts to a candle power, and 
 1000 watts is equal to 1| horse-power. We will 
 take 1000 lamps, 16 candle power. What size engine 
 will it take to run 1000 lamps allowing 3J to candle 
 power? Example: 
 
 Add 10 per 16 candle power lamp 
 cent, to the 3.5 watts to a candle power 
 
 horse-power 
 
 for friction. 80 
 
 48 
 
 56.0 watts to a 16 candle power lamp 
 1000 lamps 16 candle power each 
 
 Lamps 1000)56000.0(56 total watts, this is 56 Kilowatt 
 5000 machine 
 
 6000 1^ horse equal 1000 watts. 
 
 6000 
 
 56 
 
 181 
 
 75 horse-power 
 
 7 percentage ' 74f we would say 75 horse- 
 
 — power 
 
 82 horse-power, best to say 90 horse-power 
 
 If you had 200 volts and wanted to find what 
 amperage you ought to have, then 56,000 watts 
 -^ 200 = 280 amperes. 
 
118 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 Rule to find the bursting pressure of a boiler, 
 assuming the heads of the boiler are equally as strong 
 as the shell of the boiler: Diameter of the boiler 
 72 inches, thickness of the plate 13^ = . 4375, tensile 
 strength of the plate is 55,000, allowing 70 per cent, 
 strength of the seam. 
 
 55,000 X .4375 X 70 
 Radius of boiler 
 
 . 4375 thickness 
 
 55000 tensile strength 
 
 21875000 
 
 21875 
 
 24062.5000 
 
 , 70 strength of seam 
 
 half diameter of boiler 36) 16843 . 750000(467 . 88 bursting 
 144 pressure 
 
 244 
 216 
 
 283 
 252 
 
 317 
 
 288 
 
 295 
 
 288 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 119 
 
 Rule to find the working- pressure when you get 
 the bursting pressure of a boiler, assuming the 
 heads of the boiler are equally as strong as the shell 
 of the boiler : Diameter of the boiler 72 inches, thick- 
 ness of the plate j-q = .4375, tensile strength of the 
 plate is 55,000, allowing 70 per cent, strength of 
 the seam, factor safety ^. 
 
 55,000 X .4375 X .70 
 36 X 5 
 
 .4375 
 
 55000 T. S. 
 
 36 half boiler 21875000 
 5 factor safety 21875 
 
 180 24062.5000 
 
 . 70 strength at seam 
 
 180)16843.750000(93.57 safe working pressure 
 1620 
 
 643 
 540 
 
 1037 
 900 
 
 1375 
 1260 
 
120 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 What is the proper diameter of the feed pipe in 
 inches of an engine whose nominal horse-power is 
 140, constant multiplier .04, constant to be added 3? 
 
 140 
 
 .04 constant multiplier 
 
 5.60 - 
 
 3 constant to be added 
 
 take square root 8 . 60(2 . 93 diameter of pipe 
 4 
 
 49)460 
 441 
 
 583)1900 
 1749 
 
 What is the proper area of the injection pipe in 
 square inches of an engine whose nominal horse- 
 power is 140, constant multiplier .069, constant to 
 be added 2.81? 
 
 140 
 .069 constant multiplier 
 
 1260 
 840 
 
 9.660 
 
 2.81 constant to be added 
 
 answer 12 . 470 area of pipe 
 
MARINE AND STATIONARY ENGINEERS CATECHISM 121 
 
 To find the proper diameter of an air pump. 
 Rule: Multiply the diameter of the cylinder in 
 inches by .6. Example: Let 40 inches be diameter 
 of the cylinder then 40 inches X .6 = 24.0; which is 
 the proper diameter of the air pump on this engine. 
 
 40 diameter of cylinder 
 .6 
 
 24 . inches diameter of air pump 
 
 To find the proper diameter of a crank-pin journal: 
 Multiply the diameter of the cylinder in inches by 
 .142. Example: Diameter of cylinder 40 inches X 
 .142 = 5.680, the proper diameter of crank pin. 
 
 . 142 constant 
 40 diameter of cylinder 
 
 5 . 680 diameter of crank pin 
 
 To find the proper length of crank pin by diameter 
 of the cylinder. 
 
 Example: Diameter of cylinder is 40 inches X .16 
 = 6.40 is length crank pin. 
 
 .16 
 40 diameter of cylinder 
 
 6 . 40 length of crank pin in inches 
 
122 MARINE AND STATIONARY ENGINEERS CATECHISM 
 
 To find the proper diameter of a piston rod by 
 the diameter of the cyHnder: Let the diameter of 
 the cyHnder be 40 inches -7- 10 equal diameter of 
 the piston rod. 
 
 10)40 (4 diameter of piston rod 
 40 
 
INDEX 
 
 Page 3. To find diameter, circumference, and area of a circle. 
 
 " 4. Miscellaneous. 
 
 " 5. To reduce vulgar fraction to a decimal fraction. 
 
 " 6. Cube root. 
 
 " 6. Proportion, 
 
 " 7. Examples on proportion. 
 
 " 8. Square root. 
 
 " 9. Practical questions. 
 
 " 10. Practical questions. 
 
 " 11. Practical questions. 
 
 " 12. Practical questions. 
 
 " 13. To find the tensile strength of a boiler plate. 
 
 " 14. To find the tensile strength of a boiler plate. 
 
 " 14. What advantage does steel have over iron? 
 
 " 15. Practical questions. 
 
 " 16. Practical questions. 
 
 " 17. Practical questions. 
 
 " 17. Explain thermometer. 
 
 " 17. Practical questions. 
 
 " 18. What is a jet condenser? 
 
 " 18. Corliss engine. 
 
 " 19. Corhss engine. 
 
 " 19. Solinometer. 
 
 " 20. Solinometer. 
 
 " 21. To explain indicator and explain the card. 
 
 " 22. To explain indicator and explain the card. 
 
 " 23. To explain indicator and explain the card. 
 
 " 24. To explain indicator and explain the card. 
 
 " 24. Practical questions. 
 
 " 25. Practical questions. 
 
 " 26. Practical questions. 
 
 " 27. Practical questions. 
 
 " 28. Practical questions. 
 
 " 29. Practical questions. 
 
124 INDEX 
 
 Page 30. Practical questions. 
 " 31. Practical questions. 
 " 32. Practical questipns. 
 " 33. Practical questions. 
 " 34. Practical questions. 
 " 35. Practical questions. 
 " 36. Practical questions. 
 " 36. Dynamo electric questions. 
 " 37. Dynamo electric questions. 
 " 38. Dynamo electric questions. 
 " 39. Dynamo electric questions. 
 " 40. Starting and charging an ammonia plant. 
 " 41. Starting and charging an ammonia plant. 
 " 42. Starting and charging an ammonia plant. 
 " 42. Practical questions. 
 " 43. Practical questions. 
 " 43. The question is often asked: Why is it necessary to 
 
 make the longitudinal seam so much stronger than 
 
 the transverse or girth seam? 
 " 44. The question is often asked: Why is it necessary to 
 
 make the longitudinal seam so much stronger than 
 
 the transverse or girth seam? 
 " 44. To find the amount of water discharged through a 
 
 pipe. 
 " 45. Rule to change the water end on a pump. 
 " 46. To find the number of gallons a pump will pump. 
 " 47. Donkey pump: to find the pressure it will pump 
 
 against. 
 " 47. Take the same pump to find the height it will pump. 
 " 48. To find the horse-power of a pump. 
 " 49. Donkey-pump rule. 
 " 49. What is the horse-power of a boiler. 
 " 50. Rule to find the thickness of a casting when you have 
 
 the inside diameter and steam pressure. 
 " 50. To find the pressure on a guide slipper. 
 " 51. To find the pressure on crank pin. 
 " 51. To find the pressure on a thrust bearing. 
 " 52. To find the speed of a side-wheel steamer. 
 " 52. To find the speed of a ship. 
 " 53. To find the speed of a ship. 
 
Page 55. 
 
 
 56. 
 
 
 57. 
 
 
 58. 
 
 
 58, 
 
 
 58, 
 
 
 59. 
 
 
 60. 
 
 
 61. 
 
 
 62. 
 
 
 63. 
 
 
 64. 
 
 
 65. 
 
 
 66. 
 
 
 67. 
 
 INDEX 125 
 
 To find the speed of a ship. 
 
 To find the pitch of a wheel. 
 
 To find how many knots a ship will make. 
 
 To find the slip of a wheel. 
 
 To find the slip of a wheel. 
 
 To find the pressure on a piston. 
 
 Engine counter. 
 
 Safety valve. 
 
 Safety valve. 
 
 Safety valve. 
 
 Rule for round tank. 
 
 Rule for round tank. 
 
 Square tank. 
 
 Rule for round tank. 
 
 Rule for round tank. 
 
 68. Rule for round tank. 
 
 69. To find the number of stays to put in fiat-bottom 
 
 boiler. 
 
 70. To find the steam pressure on flat-bottom boiler. 
 
 71. To find the working pressure on round boiler. 
 
 71. Corrugated furnace. 
 
 72. To find the number of rivets to hold steam dome 
 
 down. 
 
 73. To find the size of a safety valve to place on a boiler 
 
 by the square feet of grate surface. 
 
 74. To find the pitch of staybolts. 
 
 74. To find the thickness of plate in a boiler. 
 
 75. To find the pitch of stays in a boiler. 
 
 76. To find the working pressure on triple-riveted boiler. 
 
 77. To find the working pressure on triple-riveted boiler. 
 
 78. To find the diameter of any stay. 
 
 79. To find the steam pressure you would allow on a stay. 
 
 80. To find the steam pressure you would allow on a stay. 
 
 81. To find the number of stays to put in flat surface. 
 
 82. To find the number of square inches over the tubes 
 
 in a Scotch boiler. 
 
 83. To find the working pressure on straight furnace. 
 
 83. Convex and concave heads. 
 
 84. To find the working pressure by the seam of a boiler. 
 
 85. To find the tensile strength of a boiler. 
 
126 INDEX 
 
 85. To find the diameter of a boiler, 
 
 86. Rule to brace the head of a boiler. 
 
 87. Rule to brace the head of a boiler. 
 
 88. The quickest way to get the horse-power of a boiler. 
 
 89. Rule to find the correct pitch of a rivet single- 
 
 riveted. 
 
 90. Rule to find the correct pitch of a double-staggered 
 
 rivet. 
 
 91. To find the coal burned per pounds per horse-power. 
 
 92. To find the working pressure on straight furnace. 
 
 93. To find the lift of a valve. 
 
 93. To find the percentage of ashes from coal burned. 
 
 94. Coal bunkers. 
 
 95. Coal bunkers. 
 
 96. Coal bunkers. 
 
 97. Coal bunkers. 
 
 98. To find the weight to be placed on the end of a 
 
 lever to balance a weight on the opposite end of 
 lever. 
 
 99. To find the stroke of an air pump. 
 100. To point off an indicator card. 
 
 100. To find the pressure on piston when speed is reduced. 
 
 101. To find the total pressure in pounds or tons on a 
 
 shaft. 
 
 102. To find the thickness of a corrugated furnace. 
 
 102. To find the weight of a safety ball. 
 
 103. To find the area of any circle without using .7854. 
 
 103. To find the diameter of shaft of a compound engine. 
 
 104. To find the diameter of steam pipe when you have 
 
 the horse-power. 
 
 104. To find how many times the steam expands in 
 
 compound engine or triple-expansion engine. 
 
 105. To find the pressure on a blow-off cock when it is 
 
 under water. 
 
 105. To find the number of gallons of oil in a barrel. 
 
 106. The question is asked: What is steel? 
 
 106. The question is asked: What is alloy? 
 
 107. Rule to find the diameter of a cylinder. 
 
 108. Rule to find the area and the diameter of a circle. 
 108. Rule to find the horse-power of a dynamo. 
 
INDEX 127 
 
 Page 109. To find the limit speed on stationary engine driving- 
 wheel. 
 " 109. Rule to find the area of any stay under one inch. 
 " 110. Rule to find the inside diameter of a cylinder when 
 
 you have the number of bolts and the distance 
 
 apart. 
 " 110. Rule to find how many pounds of coal and how 
 
 many tons of coal a boiler will burn in 24 hours. 
 " 111. To find the number of bolts to put in cylinder head. 
 " 112. To find the number of bolts, when the diameter of 
 
 the bolt and the pitch is given, to put in cylinder 
 
 cover. 
 " 113. To find the indicated horse-power exerted on truss 
 
 block. 
 " 114. Rule to find the pressure per square inch of steam 
 
 on a piston by the indicated horse-power. 
 " 115. Rule to find the required time to pump a given 
 
 quantity of water when two or more pumps of 
 
 different sizes are employed to empty a tank. 
 " 116. To explain an evaporator. 
 " 117. Rule to find the horse-power of an engine to run a 
 
 number of incandescent electric lights. 
 " 118. To find the bursting pressure of a boiler, assuming 
 
 the heads of the boiler are equally as strong as the 
 
 shell. 
 " 119. To find the working pressure when you have burst- 
 ing pressure on a boiler. 
 " 120. Proper diameter of feed pipe from horse-power of 
 
 an engine. 
 " 120. Proper diameter of injection pipe from horse-power 
 
 of an engine. 
 " 121. To find the diameter of air pump by diameter of 
 
 the cylinder. 
 " 121. To find the diameter of crank pin by diameter of 
 
 cylinder. 
 " 121. To find the length of crank pin by the diameter of 
 
 cylinder. 
 " 122. To find the diameter of the piston rod by diameter 
 
 of cylinder.