UNIVERSITY OF CALIFORNIA 
 
 ANDREW 
 
 SMITH 
 
 HALLIDIE: 
 
 ... I -,:/:,;.Y, ,.--. 
 
 " " ' 
 

LOCOMOTIVE SPARKS. 
 
 BY 
 
 W. F. M. 
 
 DEAN OF THE SCHOOLS OF ENGINEERING 
 
 AND 
 
 DIRECTOR OF THE ENGINEERING LABORATORY, 
 PURDUE UNIVERSITY. 
 
 FIRST EDITION. 
 FIRST THOUSAND. 
 
 NEW YORK: 
 
 JOHN WILEY & SONS. 
 
 LONDON: CHAPMAN & HALL, LIMITED. 
 
 1902. 
 
^ 
 
 fc u 
 
 Copyright, 1902, 
 
 BV 
 W. F. M. GOSS. 
 
 ROBERT DRUMMOND, PRINTER, NEW YORK. 
 

 PREFACE. 
 
 A STUDY of fuel-losses from locomotives, in the form of 
 sparks, was first made by the author in 1896. From this study 
 the work has gradually been extended to embrace other phases 
 of the spark problem until a considerable amount of data has 
 been collected. Meanwhile, a description of the early work 
 having been published, there were received at the laboratory 
 so many inquiries for information concerning sparks that it 
 has seemed best to summarize and publish the facts now in 
 hand. In selecting data for presentation, an effort has been 
 made to serve students of locomotive performance as well as 
 those who may be concerned with more practical problems. 
 Facts are presented which it is hoped will be found useful to 
 those who have to deal with fuel saving, those who may be 
 interested in the design of spark-arresters or front-end appli- 
 ances, and those who are concerned with the dangers of acci- 
 dental fires from sparks. 
 
 Acknowledgment is due Messrs. Lewis S. Kinnaird, Alfred 
 R. Kipp, George F. Mug, Charles Ducas, and Jay B. Dill, 
 who, while students at Purdue, were interested in advancing 
 some phase of the whole research. Published results which 
 have been most valuable are those of Messrs. Robert Quayle, 
 Edwin M. Herr, Charles H. Quereau, Herr von Borries, and 
 
 116756 
 
iv PREFACE. 
 
 Mr. J. Snowden Bell. Individual credit is, so far as prac- 
 ticable, given elsewhere. The author is especially indebted 
 to Mr. Ducas for courteous and generous assistance in the ar- 
 rangement of data for publication, and in the preparation of 
 illustrations. 
 
 W. F. M. G. 
 
 ENGINEERING LABORATORY, PURDUE UNIVERSITY, 
 LAFAYETTE, IND., October, 1901. 
 
TABLE OF CONTENTS. 
 
 CHAPTER I. 
 
 THE LOCOMOTIVE. 
 
 PAGE 
 
 I. Fundamental Conceptions ...................................... r 
 
 CHAPTER II. 
 
 CONDITIONS AFFECTING FURNACE ACTION IN A LOCOMOTIVE. 
 
 2. The Locomotive-furnace ........................................ 7 
 
 3. Rates of Combustion in the Furnaces of Locomotives ............ g 
 
 4. Rates of Combustion and Grate-areas .......................... 10 
 
 5- Draft ......... . ............................................ .... 14 
 
 CHAPTER III. 
 
 CINDERS AND SPARKS. 
 
 6. How Cinders are Made ......................................... T 6 
 
 7. Front-end Cinders ............................................. I7 
 
 8. Sparks ....................................................... 18 
 
 g. Conditions Affecting the Production of Cinders and Sparks ...... 18 
 
 10. Experiments to Determine the Extent of Spark-losses ............ ig 
 
 11. Size of Front-end Cinders and Sparks ........................... 21 
 
 12. The Loss of Fuel by Cinders and Sparks ........................ 27 
 
 13. Heating Value and Coal Equivalent of Sparks ................... 33 
 
 14. Conclusions as to Cinder- and Spark-losses ...................... 35 
 
 CHAPTER IV. 
 
 SPARK PREVENTION FRONT-END ARRANGEMENTS. 
 
 15. Spark Prevention .............................................. 37 
 
 16. Increased Grate-area ................................. ......... 37 
 
 v 
 
VI TABLE OF CONTENTS. 
 
 PAGE 
 
 17. The Brick Arch 38- 
 
 18. A Typical Front-end 38 
 
 19. Diaphragm or Baffle-plate 41 
 
 20 . Netting 43 
 
 21. Petticoat-pipe 45 
 
 22. Exhaust-pipe 46 
 
 23. Exhaust-tip 49 
 
 24. Smoke-stack 50 
 
 25. Extended Front-end 50 
 
 26. Practice in Front-end Arrangements 53 
 
 27. Authorities on the Front-end 72 
 
 CHAPTER V. 
 
 THE ACTION OF THE EXHAUST-JET AND THE DISTRIBUTION OF SPARKS 
 WITHIN THE STACK. 
 
 28. Experiments to Determine the Character of the Exhaust-jet 74 
 
 29. The Action of the Exhaust-jet 79 
 
 30. Distribution of Sparks within the Stack 85 
 
 CHAPTER VI. 
 
 SPREAD OF SPARKS AS DISCLOSED BY OBSERVATIONS ALONG 
 THE RIGHT-OF-WAY. 
 
 31. Experiments and Results. . .' 89 
 
 32. A Summarized Statement of Results 128 
 
 CHAPTER VII. 
 
 THEORETICAL CONSIDERATIONS AFFECTING THE SPREAD OF SPARKS 
 BY MOVING LOCOMOTIVES. 
 
 33. Purpose 129 
 
 34. Preliminary Conceptions 129 
 
 35. The Horizontal Displacement of a Body in Air under the Influ- 
 
 ence of Gravity and the Wind 130 
 
 36. The Horizontal Displacement of a Body Projected Vertically 
 
 Upwards under the Influence of Gravity and the Wind 133 
 
 37. The Horizontal Displacement of Sparks 136 
 
 38. The Effect of the Direction of the Wind on the Distance from the 
 
 Track to which Sparks may be Carried 139 
 
 39. Effect of Train's Motion on the Distance from the Centre of the 
 
 Track at which Sparks find Lodgement 141 
 
TABLE OF CONTENTS. vn 
 
 CHAPTER VIII. 
 
 CHANCES OF FIRE FROM SPARKS. 
 
 PAGE 
 
 40. A Review of Certain Facts already Presented 145 
 
 41. The Influence of Air-currents about a Moving Train 148 
 
 42. Sparks from a Locomotive and Sparks from a Fixed Fire are not 
 
 Subjected to the Same Influences 150 
 
 APPENDIX. 
 
 THE PURDUE UNIVERSITY LOCOMOTIVE TESTING-PLANT. 
 
 43. Development of the Plant 153 
 
 44. The Wheel-foundation 155 
 
 45. The Traction Dynamometer 159 
 
 46. The Superstructure 160 
 
 47. The Building 163 
 
LOCOMOTIVE SPARKS. 
 
 CHAPTER I. 
 
 THE LOCOMOTIVE. 
 t 
 
 i. Fundamental Conceptions. The boiler and engine of 
 a locomotive are similar in their general character to the boiler 
 and engine which go to make up a stationary power-plant. 
 Each exists for the purpose of converting into work the poten- 
 tial energy of fuel. There are differences in the details of 
 mechanism, and in the conditions under which work is per- 
 formed, but the principles underlying action are the same. 
 
 As compared with the locomotive, the stationary plant has 
 an advantage in being fixed in its position. It may be so 
 arranged that all its parts are accessible to attendants, who in 
 doing their work may pass freely from one element to another," 
 and any detail which is better when made large can be given 
 such dimensions as will insure its efficient and otherwise satis- 
 factory performance. In many cases there are no limiting 
 dimensions ; the plant may be built as long and as wide and as 
 high as may be desired. It is possible, therefore, to so con- 
 struct the engines, boilers, and accessory apparatus which go 
 to make up a stationary plant, as to secure any desired degree 
 
2 LOCOMOTIVE SPARKS. 
 
 of efficiency, within limits which are prescribed by the state 
 of the art. If the pulsating sound of escaping steam is objec- 
 tionable, it can be entirely eliminated by the application of a 
 suitable exhaust-head or muffler. If the presence of a cloud 
 of exhaust-steam is annoying, it may be entirely suppressed 
 by the use of a condenser. If smoke emerging from the top 
 of the stack becomes a nuisance, it may be made to disappear 
 by the use of down-draft furnaces, or by the application of 
 some other form of so-called smoke-consumer. If economy 
 in the use of fuel is an important consideration, small and 
 overworked boilers may be made to give way to others which 
 provide a more liberal allowance of heating-surface. Engines 
 having atmospheric exhaust may give way to condensing 
 engines, simple engines to compounds, and compounds to 
 triple-expansions. The degree of perfection which may be 
 obtained in any or all of these particulars is in fact a matter 
 which is entirely within the choice of the designer, subject only 
 to such limitations as to cost as may be imposed by business 
 considerations. 
 
 In passing from stationary power-plants to moving power- 
 plants in the form of locomotives, the designer gives up his 
 freedom of choice with reference to many matters of detail, 
 and finds himself confronted with the necessity of having his 
 work conform to certain general conditions. The work 
 which his boiler and engine are to do must be made to appear 
 in the motion of the plant itself and its attached train. The 
 fact that the whole plant must move across the country with a 
 velocity equal to that attained by the periphery of the stationary 
 engine's fly-wheel, requires the adoption of a cycle which shall 
 serve to transfer the heat-energy of the fuel into work, by as 
 direct a process as practicable. 
 
 The stationary plant runs at a fixed speed and usually at a 
 
 . 
 
THE LOCOMOTIVE. 3 
 
 fairly constant load ; the locomotive must run at all speeds ; it 
 must climb hills, pulling slowly and hard, and it must roll 
 rapidly into valleys, holding back a train which would push it 
 on at still higher speeds. 
 
 Important elements must be adapted one to another, and 
 there must be an entire omission of many details which in good 
 practice are considered necessary to the economical working 
 of a stationary plant. The moving parts of a stationary engine 
 work in a substantial frame, which in turn is bolted to a massive 
 foundation, while the frame of a locomotive is suspended by 
 springs from axles carried by wheels which are supported by 
 a yielding and uneven track. The action of the stationary 
 engine can be one of precision, and delicate and precise devices 
 may be embodied in its mechanism which are not at all 
 admissible in the less rigid structure of the locomotive. The 
 stationary engine is protected from the weather and from dust, 
 while the locomotive must give no trouble if worked in rain or 
 snow, or in clouds of dust. 
 
 The designer of a locomotive, moreover, is forced to recog- 
 nize that the machine with which he is concerned constitutes 
 but one of many elements which go to make up the material 
 property of a railroad. The width between the wheels of his 
 engine is prescribed by the gage of the track, and the length 
 of its wheel-base by the curvature of track, the length of turn- 
 tables, and the dimensions of other facilities at the terminals 
 of the road. The extreme width and height of the machine 
 must come within the limits of clearance which are allowed on 
 either side and above the track, for the locomotive which he 
 designs must pass station-platforms, underneath bridges, and 
 through tunnels. 
 
 With such limiting conditions as have been indicated, the 
 locomotive designer has for many years been under the neces- 
 
4 LOCOMOTIVE SPARKS. 
 
 sity of producing locomotives which will carry greater loads 
 and move at higher speeds than those which have preceded 
 them. Locomotives which could carry twenty cars have given 
 way to newer and larger machines which are capable of carry- 
 ing forty cars, and trains which used to be pulled at a speed of 
 twenty-five miles an hour must now be carried at fifty miles 
 an hour. 
 
 With restraining conditions fixing limits which are absolute, 
 and acting under the influence of a growing demand for 
 increased power, it has been necessary for the locomotive 
 designer to consider economy in the use of fuel as a matter of 
 secondary importance. The problems of reducing noise and of 
 abating smoke have received such attention as the conditions 
 have allowed, but each proposition dealing with these purely 
 secondary questions has of necessity been weighed by him 
 with reference to their effect on the output of power. He 
 knows that smoke from a locomotive can be suppressed, but 
 he also knows that in accomplishing this the firing will be 
 interfered with and the power of the locomotive will be 
 reduced. It is to be noted, also, that the need for power is 
 not one which he has artificially created, but is the outgrowth 
 of a public demand for service. There is in fact no serious 
 defect in the working of the modern locomotive that is not 
 understood and appreciated by the locomotive designer. He 
 allows them to exist because all efforts to overcome them 
 appear to work to the disadvantage of more important charac- 
 teristics of his machine. 
 
 It is but just to add that present-day designers of locomo- 
 tives have not rested on the achievements of their predecessors 
 but have added thereto a full measure of their own indi- 
 viduality. 
 
 The significance of their achievements is to be seen in 
 
THE LOCOMOTIVE. 
 
 SCALE IN FEET 
 5 10 IS 20 26 
 
 TWO, 500. H. P. 
 ENGINES 
 
 
 FIG. i. 
 
6 LOCOMOTIVE SPARKS. 
 
 Fig. i,* which shows two power-plants, each of a thousand 
 horse-power. Both are drawn to the same scale, so that a 
 comparison of the figures discloses their relative dimensions. 
 
 The smaller of the two drawings represents a modern loco- 
 motive having 2500 feet of heating-surface and 20" X 24" 
 cylinders, and consequently quite capable of delivering the 
 power assigned it. The stationary plant represented by the 
 larger drawing is not more liberal in its dimensions than such 
 plants have need to be. It is made up of a suitable building 
 containing a battery of boilers and two slow-speed engines of 
 500 horse-power each. 
 
 The drawings tell their own story. Those of the stationary 
 plant cover an area of paper which is many times greater than 
 that covered by the drawings of the locomotive and yet the 
 power capabilities of the two plants are the same. It is evident 
 that a process which permits the smaller apparatus to equal 
 that of the larger must be one of unusual activity. 
 
 When one is inclined to criticize the locomotive because it 
 is somewhat less economical in fuel than the stationary plant, 
 or because it sometimes smokes a little or sends out a few 
 sparks, he should look at these drawings for he will find in 
 them a ready explanation and excuse. 
 
 * From the Railroad Gazette, July 20, 1900. 
 
CHAPTER II. 
 
 CONDITIONS CONTROLLING FURNACE-ACTION IN A 
 LOCOMOTIVE. 
 
 2. The Locomotive-furnace. A vertical section of a loco- 
 motive-boiler is shown by Fig. 2. The drawing is to be 
 considered somewhat diagrammatical since it does not include 
 minor details. 
 
 The furnace or fire-box, as it is often called, is at A. It 
 consists of a chamber of steel surrounded at the top and on the 
 sides by the water of the boiler. The bottom of the furnace 
 is fitted with a suitable fire-grate upon which fuel is burned. 
 An opening at the back serves as a fire-door. Below the grate 
 there is ordinarily a sheet-iron ash-pan but this does not appear 
 in the drawing. 
 
 The front sheet of the fire-box, known as the tube-sheet, 
 receives the end of tubes which usually are 2 inches in diameter 
 and which extend to the front head of the boiler, C. The 
 exterior surfaces of the tubes are in contact with the water of 
 the boiler while their interior surface constitutes a way of 
 escape for the furnace-gases. All the products of combustion 
 resulting from the furnace-action pass from the furnace through 
 the tubes into the front-end or smoke-box, D. In passing 
 the tubes the gases from the furnace give up much of their heat 
 to the surrounding water, the tube-surface constituting a very 
 large fraction of the entire heating-surface of the boiler. From 
 the front-end, D, the gases from the furnace intermingle with 
 
 7 
 
LOCOMOTIVE SPARKS. 
 
CONDITIONS CONTROLLING FURNACE-ACTION. 9 
 
 the exhaust-steam escaping from the pipe E, and are forced up 
 the stack and out into the atmosphere. When the engine is 
 working there is a constant movement of air and heated gases 
 from the grate into the furnace, through the tubes, into the 
 front-end, and up the stack. 
 
 3. Rates of Combustion in the Furnace of Locomotives. 
 It has already been shown that the locomotive is a small 
 machine, when measured by the amount of work demanded of 
 it, and it follows that some or all of its parts are worked to a 
 higher pitch than the similar parts of plants which have more 
 liberal dimensions. This statement is especially true in its 
 application to the locomotive fire-box, for the power developed 
 by locomotives is derived from the fuel it burns, and, other 
 things being equal, whatever operates to increase the amount 
 of coal consumed contributes to an increase of power. With 
 a steady growth in the size of locomotives, there has been a 
 corresponding increase in the amount of coal to be handled, 
 until now it is not uncommon for a modern engine to require 
 as much as 5000 pounds or more for each hour it runs, or 83 
 pounds a minute. Coal thus required is burned in a fire-box, 
 the dimensions of which are limited by the general arrange- 
 ment of other important parts of the machine. With large 
 quantities of coal to be burned, in a furnace of small dimen- 
 sions, the process of combustion is of necessity an active one, 
 as will be seen by the following comparisons. 
 
 Soft coal upon a grate in the open air will burn at about 
 the rate of 3 pounds an hour for each square foot of grate-sur- 
 face. In a heating-stove, under usual conditions of draft, there 
 will be burned about 5 pounds for each foot of grate, and under 
 a stationary boiler connected with a good stack, the rate may 
 increase to 10 or even to 20 pounds per foot of grate. Again, 
 in naval practice with a closed stack-hole and draft forced by 
 
io ' LOCOMOTIVE SPARKS. 
 
 blowers, the rate of combustion is occasionally carried as high 
 as 50 pounds per foot of grate per hour, but this value may be 
 accepted as the maximum rate at which fuel is burned for the 
 purpose of generating steam, except in locomotives. Under 
 the lightest service incident to common practice in the narrow 
 fire-boxes of locomotives, the rate is between 50 and 100 
 pounds, and good practice allows it to rise above 150 pounds, 
 or to three times the rate attained under the conditions of 
 forced draft in naval service. Nowhere are fires urged with 
 greater intensity except in forges or in furnaces employed for 
 metallurgical purposes. 
 
 Stating the same fact from a different point of view, it may 
 be said that the grate of a modern locomotive has an area 
 equal to that of a small-sized dining-table. The amount of 
 coal burned on it is so large that if burned in the open air in 
 the form of a bonfire it could only be consumed by making 
 the fire cover an area of a thousand square feet or, say, a grate 
 io feet wide and 100 feet long. 
 
 4. Rates of Combustion and Grate-areas. The preceding 
 general statements concerning rates of combustion in locomo- 
 tive-furnaces may be accepted as fairly representative of condi- 
 tions prevailing in good American practice. In order that a 
 fuller view may be had of the subject, it will be well to 
 consider for a moment what are the conditions governing the 
 rates of combustion, and the expedients which have been 
 resorted to by the American designer in his efforts to keep 
 them within reasonable limits. 
 
 As already indicated, the intensity of the burning is well 
 expressed by the pounds of coal consumed per unit area of 
 grate. When 20 pounds of coal are burned per foot of grate- 
 surface each hour, the process of combustion is double in its 
 intensity that which attends the burning of io pounds on the 
 
CONDITIONS CONTROLLING FURNACE-ACTION. ir 
 
 same area in the same time. It is evident, also, that with a 
 given total weight of coal to be burned, the rate of combustion 
 will be inversely proportional to the area of the grate; that 
 is, as the grate is increased in size, the rate of combustion 
 will be diminished. In their desire to keep the rate of 
 combustion within reasonable limits, locomotive designers 
 have continually sought means whereby the grate might be 
 enlarged. 
 
 Previous to 1 890 practically all American locomotives were 
 built along the same general lines The fire-box extended 
 down between the side-frames, while the axle of the forward 
 drivers passed across in front and that of the rear drivers behind. 
 Under these conditions, the maximum width of the grate was 
 between 34 and 35 inches. It could not be made 'materially 
 greater without widening the gage of the track. The length 
 of the grate was determined by the spacing of the two axles 
 already referred to, and which were ordinarily 8 feet apart, the 
 feeling being that the coupling-rods by which the drivers of 
 each side are connected, one with another, should not be 
 longer than was necessary to span this distance. With these 
 limitations, after allowing clearance for axles and eccentrics, 
 the maximum length of the grate could be about 75 inches. 
 A width of 35 inches and a length of 75 inches gives an area 
 of about 1 8 feet. For a time it appeared that this must remain 
 the maximum size of grate. Gradually, however, side-rods 
 were lengthend to 8J and even 9 feet, with a corresponding 
 gain in length of grate. At the same time, also, there began 
 the practice of sloping the grate and raising the centre line of 
 the whole boiler. By these means the back of the grate was 
 brought sufficiently high to pass over the rear axles, permitting 
 the fire-box to extend rearward an indefinite distance. The 
 practical limit to the length of grate under these conditions 
 
12 LOCOMOTIVE SPARKS. 
 
 was, however, found to be the distance from the fire-door at 
 which a fireman could spread coal over the forward end of the 
 grate a distance which could not be allowed to exceed 10 
 feet; and in many cases the maximum length was fixed at 
 9 feet. By these means the grate-area was made to approach 
 30 square feet. 
 
 The next great step was taken when the boiler was still 
 further raised, the depth of the fire-box diminished, and the 
 form of the frame modified so that the fire-box could rest on 
 top of the frames instead of extending between them. This 
 enabled the width of the grate to be increased by an amount 
 equal to the sum of the width of the two side-frames which is 
 from 8 to 10 inches. This change permitted an extension of 
 grate-area to about 36 feet but in the case of the eight-wheeled 
 type of engine no further increase of area can be had by 
 widening the fire-box which must still come between the 
 drivers. 
 
 Further extensions in grate-area can, however, be had by 
 the adoption of such a modification in wheel arrangement as 
 will permit the fire-box to be extended sidewise beyond the 
 gage of the track. Such exceptional designs have from time 
 to time appeared, the most noteworthy being the Wootten 
 boiler, having a shallow fire-box extending out over the 
 wheels, giving an area of from 60 to 85 square feet. To allow 
 the use of so wide a structure, the coupled drivers are brought 
 close together and placed ahead of the fire-box, the rear of the 
 engine being carried on a pair of small trailing wheels, over 
 the top of which the fire-box is free to extend. Locomotives 
 having such a wheel arrangement have come to be known as 
 of the Atlantic type. 
 
 The Wootten boiler was originally designed for burning fine 
 anthracite coal which needs to be spread very thin and per- 
 
CONDITIONS CONTROLLING FURNACE-ACTION. 13 
 
 mitted to burn at a comparatively low rate. As the supply of 
 such coal is not general, these engines have been confined to 
 a limited area within which the fine anthracite coal is to be 
 had. It is to be noted that the Atlantic type of engine is not 
 adapted to all classes of service; also, that the Wootten boiler 
 is serviceable only in connection with the peculiar fuel which 
 it is designed to use. When tried with a lighter bituminous 
 coal, such as must be used in our Western States, it was found 
 impossible for a single fireman to keep the grate covered, with 
 the result that steam-pressure could not be maintained. The 
 fact to be emphasized is that the existence of the Wootten 
 boiler is not in itself evidence that rates of combustion in all 
 locomotives using all classes of fuel can be made low. 
 
 There are now, in 1900, evidences that the essential 
 features of the Atlantic type engine and of a modified form of 
 the Wootten boiler will be adopted in locomotives designed 
 for burning soft coal. Several roads of the Middle and 
 Western States now have wide fire-boxes in service which 
 have from 40 to 50 feet of grate-area. This is as large a grate- 
 area as can well be fired with soft coal by one man. 
 
 In spite of the gradual increase in grate-area which has 
 been noted, rates of combustion per unit of grate-area have 
 not greatly declined in recent years. Such progress as may 
 have been made in securing enlarged grates has done but little 
 more than to keep pace with the increased amounts of fuel 
 which, as engines have increased in power, are required to be 
 burned. What this rate is required to be for the development 
 of varying amounts of power is well shown by results obtained 
 in a series of tests made upon the Purdue experimental locomo- 
 tive (see Appendix). This locomotive is now to be regarded 
 as one of rather small size. It weighs 85,000 pounds, has 
 17" X 24'' cylinders and during the tests was run at a speed 
 
14 LOCOMOTIVE SPARKS. 
 
 of 35 miles an hour with a wide-open throttle and a steam- 
 pressure of 130 pounds, conditions and results as to coal 
 burned, all of which may be accepted as within the limits of 
 good practice, being as follows: 
 
 Tut off Hnrcp nnw*r Total Pounds Coal per Sq. Ft. 
 
 rer ' Coal per Hour, of Grate per hour. 
 
 6" 300 1262 72 
 
 8" 434 1978 113 
 
 10.5" 495 3133 179 
 
 5. Draft. The passage of air through a mass of burning 
 fuel constitutes what is usually known as "draft." It is by 
 the action of the draft that the process of combustion is stimu- 
 lated. If the draft is weak, the rate of combustion is low; if 
 strong, the rate of combustion becomes high. The draft is, 
 in fact, in all cases the regulator by means of which the rate 
 of combustion is controlled. It has already been shown that 
 the rate of combustion in a locomotive is abnormally high and 
 it follows that the draft must be correspondingly strong. 
 
 In a locomotive the draft results from the action of the 
 exhaust-steam which, after doing its work in the cylinders of 
 the engine, is made to pass upward through the smoke-box 
 and out by the stack in such a manner and at such velocity as 
 will induce a current in the smoke-box gases through which it 
 passes. In this manner the exhaust-jet serves not only to 
 discharge the smoke-box gases, but it draws upon them with 
 sufficient vigor to produce a partial vacuum in the front-end. 
 This condition prevails whenever the engine is in action. 
 
 With a pressure in the front-end which is less than that of 
 the atmosphere, there is a constant tendency for air to pass 
 from the atmosphere to the front-end. The only avenue is by 
 way of the ash-pan through the burning fuel, into the furnace, 
 and thence on through the tubes. The activity of this move- 
 
CONDITIONS CONTROLLING FURNACE-ACTION. 
 
 ment will evidently depend upon the difference between the 
 atmospheric pressure and the pressure in the front-end, and it 
 has become the practice to measure the intensity of the draft- 
 action in terms of this difference of pressure. The unit of 
 measure is usually taken to be the displacement of a column 
 of water I inch high, equivalent to 0.04 pound per square inch, 
 or 5.2 pounds per square foot. The draft employed in boilers 
 of stationary plants with good stacks is from o. I to 1.4 inches 
 of water. In naval practice, with closed stack-hole and forced 
 draft, it is from I to 4 inches, while in a locomotive burning 
 bituminous coal, it ranges from 3 to 10 inches, depending upon 
 the service, character of the fuel, and the condition of the fire. 
 Under ordinary conditions of service it does not often fall 
 below 6 inches, which is equivalent to a difference of pressure 
 between that of the atmosphere and that of the gases of the 
 front-end of 31 pounds per square foot. Such a draft is quite 
 comparable in intensity with that employed to urge the fire of 
 a blacksmith's forge, though in the latter case the area affected 
 is small, while in the former case, the full area of the grate is 
 affected. The relation between draft and rate of combustion 
 for the experimental locomotive of Purdue University is as 
 follows: 
 
 Reduction of Pressure in Front-end as 
 Compared with Pressure of Atmosphere. 
 
 Pounds of Coal per Square Foot of Grate 
 per Hour. 
 
 Inches of Water. 
 
 Pounds per Sq. Ft. 
 
 Brazil (Ind.) Block. 
 
 New River. 
 
 2.OO 
 
 3-34 
 4-30 
 
 10.40 
 
 17-37 
 22.36 
 
 64.14 
 II3-46 
 146.62 
 
 53-oo 
 81.00 
 
 IOO.OO 
 
CHAPTER III. 
 CINDERS AND SPARKS. 
 
 6, How Cinders are Made. The activity which charac- 
 terizes the process that goes on in the fire-box of locomotives 
 has already been described. That required rates of combustion 
 may be maintained, the air-currents passing- through the fire 
 need to be very strong. Air enters through the grate, mingles 
 for an instant with the combustible properties of the fuel, the 
 fuel burns, and the products of combustion are as quickly 
 drawn away from the fire-box, through the tubes to the front 
 end, and thence forced up the stack and into the atmosphere. 
 The whole passage from the grate, through the fire-box, and 
 into the tubes is as in a twinkle of an eye. 
 
 The layer of incandescent fuel often dances on the in-rush- 
 ing currents of air and if by chance some portions become 
 thinner than others, individual coals of considerable size are 
 tossed far above the general level of the fire, settling back and 
 awaiting for an instant a new impulse to send them up again, 
 responding to the action of 'the exhaust, just as apples keep in 
 air in response to the toss of a boy's hand. If the spot con- 
 tinues to become thinner, the strength of the draft will after a 
 time overcome the weight of the fuel, which floats away bodily, 
 leaving a <( hole " in the fire with the bare grate at the bottom. 
 
 In the midst of such conditions as these, sparks are born. 
 Light particles of coal, unless well cemented together by 
 
 water when thrown into the furnace, never reach the grate but 
 
 16 
 
CINDERS AND SPARKS. if 
 
 ignite in the flame of the furnace and partially consumed are 
 borne into the tubes. When a friable coal is used, the lumps 
 on the grate, breaking up under the action of heat, give rise 
 to many small fragments which prove too light to keep their 
 place with the more solid masses of the fire. These also fly 
 into the tubes. Much of the ash which results from the com- 
 bustion of fuel on the grate, and which in a stationary boiler 
 would drop through to the ash-pan is, in a locomotive-boiler, 
 caught up by the draft and carried into the tubes along with 
 the incandescent coke to which reference has already been 
 made. It is in this manner that the procession of cinders is. 
 formed. Every particle which enters the tubes at the fire-box 
 end is ordinarily carried through into the smoke-box. Here 
 some are entrapped. In the smoke-box they gradually cool, 
 the exclusion of outside air preventing the combustible portion 
 from burning. At the end of the run they are removed. The 
 remainder, after being baffled and knocked about by obstacles 
 set in their path, and greatly lowered in temperature by con- 
 tact with escaping steam, are thrown out from the top of the 
 stack. 
 
 7. Front-end Cinders. It will be seen that the solid 
 material entering the tubes from the fire-box has either the 
 form of living coal or that of ash. By the time it reaches the 
 front-end the coal has become coke. The mixture of finely 
 divided coke and ash which finds its way into the smoke-box 
 is indiscriminately referred to as sparks, cinders, smoke-box 
 cinders, and front-end cinders, these terms applying to the 
 material while it is within the front-end and, also, after it is 
 removed therefrom and put to various uses. Without attempt- 
 ing to discuss the reason underlying the use of these various 
 terms, that of ' ' front-end cinders ' ' will be employed for the 
 purpose of the present text. 
 
1 8 LOCOMOTIVE SPARKS. 
 
 8. Sparks. Of all the solid particles which pass through 
 the tubes and which by convention are to be called front-end 
 cinders, a portion passes out of the top of the stack. Such 
 particles are commonly spoken of as " sparks " or " cinders." 
 For the present purpose they will be called sparks. It should 
 be noted that this term is adopted merely as a definition ; it is 
 not strictly descriptive. The cinders which escape from the 
 front-end and become sparks retain all the characteristics of 
 front-end cinders. Some are composed entirely of ash. 
 Others are of coke which, in their passage of the front-end, 
 have been hammered against plates and immersed in steam 
 until they are entirely deprived of fire, and are as incapable of 
 doing damage by fire as the ash itself. All such sparks are 
 commonly referred to as " dead sparks. ' ' Still others, con- 
 stituting a very small proportion of the whole, escape at a 
 temperature sufficiently high to glow in the dark, and of these 
 it sometimes happens, where very light fuel is used, that a few 
 flame. But flaming sparks are of rare occurrence. 
 
 9. The Conditions Affecting the Production of Cinders 
 and Sparks. The production of front-end cinders and sparks 
 depends upon many variable factors. As has been shown, the 
 most active agent is to be found in the action of the draft, but 
 the condition of the fire, manner of firing, and the character of 
 the fuel, all have their influence. Fine coal, if fired dry, 
 results in more cinders and sparks than when well wetted 
 before firing. A light friable coal, even though thrown upon 
 the grate in large-sized lumps, will often, under the action of 
 heat, quickly break into smaller fragments, many of which are 
 sufficiently small to be caught up by the draft. A good 
 quality of bituminous coal which holds together well in burning 
 will give off very few live sparks, and the sparks of anthracite 
 coal are practically nothing but ash. 
 
CINDERS AND SPARKS. 19 
 
 It will be evident that conditions favorable to the produc- 
 tion of cinders and sparks are, under normal conditions of 
 working, always present ; that this fact is not the outcome of 
 improper design nor of any failure to appreciate the disadvan- 
 tages they involve on the part of those responsible for the 
 proper operation of locomotives ; but they exist as a necessary 
 consequence of the exactions of service and in spite of the 
 efforts of skillful men who have lived and worked since the day 
 of Stephenson to overcome them. 
 
 10. Experiments to Determine the Extent of Spark- 
 losses. Such experiments were first made in the laboratory 
 of Purdue University. The locomotive of this laboratory is so 
 mounted that while its machinery may be run at any speed and 
 
 
 / /' 
 
 
 1 1 "I 
 
 I 
 
 
 Hi 
 
 
 =L 
 
 M \ 
 
 
 1 '_:-.': 
 
 SLIDING J 
 FRAME 
 
 BUCKET 
 ROOF 
 
 LOCOMOTIVE STACK 
 
 -_ 
 
 FIG. 3. 
 
 under any condition of load, the locomotive as a whole main- 
 tains a fixed position. It is possible, therefore, in the case of 
 this locomotive to work about the top of the stack in a manner 
 which would be wholly inadmissible in connection with a 
 locomotive on the road. 
 
 The apparatus employed in determining the extent of spark- 
 losses is shown by Fig 3.* It consists of an inverted U tube 
 
 * From a paper on " The Effect of High Rates of Combustion upon the 
 Efficiency of Locomotive-boilers." New York Railway Club, Sept., 1896. 
 
20 
 
 LOCOMOTIVE SPARKS. 
 
 of galvanized iron, securely fastened to a movable frame, by 
 means of which the tip, which constitutes one extremity of the 
 tube, can be projected across the top of the locomotive smoke- 
 stack. The outer end of the tube may thus be made com- 
 pletely to intercept a portion of the stream issuing from the 
 stack, and the continuous action of this stream is sufficient to 
 drive the intercepted portion through the tube and out at the 
 other end. The gases passing the tube bear the sparks on 
 their current, and they are collected in a bucket set to entrap 
 them. Reference marks upon the sliding and the fixed frames 
 permit the tube to be placed in definite locations relative to the 
 centre of the stack. This device, when in service, catches 
 everything excepting the lightest soot, which is allowed to 
 escape unaccounted for. 
 
 After assuming the cross-section of the stream issuing from 
 the stack to be cut up, by a series of concentric circles, into 
 one circular and several annular areas, as shown by Fig. 4, 
 
 FIG. 4. 
 
 the small end of the U tube was placed in the position marked 
 /and held there for thirty minutes, the sparks collected during 
 this interval being credited to this position. The tube was 
 
CINDERS AND SPARKS. 21 
 
 then moved to the position //, where it remained for another 
 period of thirty minutes. In like manner, it was made to 
 occupy, successively, the positions /// and IV, and also the 
 positions 7 L , 11^ , III^ , and IV l , the weight of sparks caught 
 during each interval being credited to the corresponding posi- 
 tion occupied by the small end of the tube. This end of the 
 tube had an area of I square inch, and it was assumed that the 
 average weight of sparks passing the tube while in the positions 
 / and /j would be the same as that passing every square inch 
 in the annular space in which these positions are located. For 
 example, the outer annular area, in which / and / x are located, 
 contains 88 square inches. If, in half an hour, 0.5 pound was 
 collected by the tube in the position /, and in another half 
 hour 0.3 pound was collected from the position 7 X , the sum of 
 these two weights, or o. 8 pound, collected during a period of 
 one hour would be the average weight per square inch per 
 hour collected from the two positions, and the weight for the 
 whole outside annular area would be O.8 times 88, the number 
 of square inches, or 70.4 pounds per hour. A similar experi- 
 ment and calculation gave the weight per hour delivered by 
 each of the other annular areas // and ///, and by the circular 
 area IV. The sum of these separate determinations was 
 assumed to be the total weight of sparks per hour delivered 
 from the stack. 
 
 ii. Size of Front-end Cinders and of Sparks. So far as 
 mechanical arrangements are concerned, there is nothing to 
 limit the size of front-end cinders except the diameter of the 
 tubes through which they must pass. These generally have a 
 clear diameter of about if inches. The dimensions of front- 
 end cinders cannot exceed and seldom reach such limits. The 
 active conditions affecting their size are to be found in the 
 strength of the draft and the character of the fuel. 
 
22 LOCOMOTIVE SPARKS. 
 
 Sparks discharged from the stack are as a rule much 
 smaller than front-end cinders. After passing the tubes these 
 are met by a complicated series of obstructions which serve to 
 break them up and to stop all which exceed certain fixed 
 limits in size. What these retarding agents are, it is the prov- 
 ince of another chapter to explain. In general, it may be said 
 of sparks, as of front-end cinders, that their size depends upon 
 the draft and the character of the fuel. 
 
 An exhibit of typical cinders and sparks is presented as 
 Figs. 5 and 6. In each case the pile A is made up of sparks 
 emitted from the top of the stack, collected in the manner 
 already described, while the pile B is composed of cinders 
 taken from the front-end after a run. For purposes of com- 
 parison, a pile of buckshot (C) is added, the diameter of the 
 individual shot being T 5 ^ of an inch. The sparks and cinders 
 making up Fig. 5 represent conditions of heavy running. 
 They were obtained during a test for which the draft was 
 represented by 7 inches of water and the rate of combustion 
 was 221 pounds of coal per foot of grate per hour. Fig. 6 
 represents conditions of light running, the materials shown 
 having been obtained during a test for which the draft was 
 represented by 3 inches of water and the rate of combustion 
 was 84 pounds of coal per foot of grate per hour. The coal 
 was Brazil block and the tests were made on the experimental 
 plant of Purdue University. The materials shown on both 
 figures may be accepted as representative of all that accumu- 
 lated during tests of several hours' duration, and as extreme 
 conditions are represented, it is but fair to presume that the 
 largest sparks which are likely to be given off from the stack 
 by an engine in good condition are those shown by A, Fig. 5, 
 and that under lighter conditions of running they may not run 
 larger than those shown by A, Fig. 6. 
 
CINDERS AND SPARKS. 27 
 
 12. The Loss of Fuel by Cinders and Sparks The total 
 cinder- and spark -loss for any given period is found by ascer- 
 taining the weight of the solid material which accumulates in 
 the front-end and the weight which is discharged from the top 
 of the stack. Weighings of the front-end cinders are readily 
 made at the end of a run and the weight of sparks passing out 
 of the stack may be determined by the method already 
 described. 
 
 Results of an investigation thus made are presented in 
 Table I. 
 
 TABLE I. 
 
 SHOWING WEIGHT OF CINDERS AND SPARKS FROM THE 
 PURDUE LOCOMOTIVE, SCHENECTADY NO. 1, WHEN 
 USING BRAZIL BLOCK COAL. 
 
 
 
 
 
 3 
 
 g^ 
 
 M 
 
 
 JS 
 
 -C Q 
 
 
 S. 
 
 WJ3 C 
 
 
 
 o 
 
 Ego. 
 
 l 
 
 v" 
 
 c 
 
 Li 
 
 1 
 
 1 
 
 > 0^ 
 
 U3 
 
 0^3 
 
 1 fe S 
 
 H 
 
 P 
 
 a, 
 
 !_. c ** 
 
 <NM 
 
 
 ^^^O 
 
 U 
 
 C 
 
 a j- 
 
 O U *u 
 
 t/3 o -' 
 
 ^.SK 
 
 rt u* 
 
 O 2 o w 
 
 
 
 ^ 
 
 "o ^ 
 
 
 g& 
 
 s-f ^ 7 
 O Vw 
 
 "o tuto 
 
 4_, U 
 
 
 
 ^S ^rT 
 
 rti 
 
 c . 
 
 C *-* ctf 
 
 C J:* 
 
 
 
 Gfl jT V ^ 
 
 c/) .S E 
 
 w *s" O. 
 
 - i; i-p 
 
 ^ C k* 
 
 
 
 g 
 
 3 1 
 
 ~>t 
 
 Z * 
 
 a* 
 
 "c^ o 
 
 "g'g u 
 
 "c 3 t3 
 
 "rt C U 
 
 rt"g 
 
 3 
 
 
 'i-j2 
 
 u^ 
 
 
 o aOE 
 
 0^ O 
 
 gcj S 
 
 SO a 
 
 ^"ocAU 
 
 
 
 (/} 
 
 h 
 
 Q 
 
 H 
 
 a. 
 
 CH 
 
 CU 
 
 H 
 
 (X 
 
 I. 
 
 II. 
 
 III. 
 
 IV. 
 
 V. 
 
 VI. 
 
 VII. 
 
 VIII. 
 
 IX. 
 
 X. 
 
 I 
 
 15 
 
 I 
 
 1-93 
 
 79L5 
 
 45.23 
 
 21.90 
 
 12.30 
 
 34-20 
 
 .043 
 
 2 
 
 35 
 
 I 
 
 2.98 
 
 1464.8 
 
 83.70 
 
 41.20 
 
 63.20 
 
 104.4 
 
 .071 
 
 3 
 
 35 
 
 I 
 
 3-02 
 
 1513.6 
 
 86.50 
 
 46.10 
 
 49.90 
 
 96.00 
 
 .063 
 
 4 
 
 35 
 
 I 
 
 3-oo 
 
 I557.I 
 
 88.98 
 
 45.00 
 
 63-40 
 
 108.4 
 
 .070 
 
 5 
 
 55 
 
 I 
 
 3-57 
 
 1884.4 
 
 107.68 
 
 127.5 
 
 157-2 
 
 284.7 
 
 151 
 
 6 
 
 35 
 
 3 
 
 4.88 
 
 2017.7 
 
 115.29 
 
 IIO.O 
 
 67.30 
 
 177-3 
 
 .088 
 
 7 
 
 15 
 
 9 
 
 4-99 
 
 2I2I.O 
 
 121.20 
 
 215.5 
 
 78.00 
 
 293-5 
 
 .138 
 
 It is to be noted from the data given in Table I that the 
 draft conditions for the tests under consideration range from 2 
 to 5 inches of water ; that the coal burned per hour varies from 
 
28 LOCOMOTIVE SP4RKS. 
 
 790 to 2100 pounds, which is equivalent to a rate per hour of 
 from 45 to 12 I pounds per foot of grate. 
 
 The weight of sparks passing up the stack, and cinders col- 
 lecting in the front-end per hour, respectively, are given in 
 Columns VII and VIII, while the total weight appears in 
 column IX. 
 
 Column X gives the ratio of total weight of sparks and 
 cinders to the total weight of coal. It shows that the losses 
 arising from this cause vary from a little more than 4 per cent 
 to nearly 14 percent of the weight of coal fired, the loss being 
 greatest when the rate of combustion is highest. The relation 
 between the rate of combustion, weight of cinders caught in 
 front-end, the weight of sparks passing out at the stack, and 
 the total weight of sparks and cinders, is shown graphically 
 by Fig. 7, which is plotted from the data given in Table I. 
 The relation between the weight of sparks passing out at the 
 stack and the weight of cinders retained in the front-end as 
 shown by these tests, is not considered conclusive since it must 
 depend somewhat on the length of the test, that is, upon the 
 frequency with which the front-end is cleaned, but the facts 
 are presented as obtained. It appears, however, that Test 
 No. I shows a larger loss by the stack than by the front-end 
 but the value of the whole loss for this test is small. Disre- 
 garding this test, it appears in general that the spark-losses as 
 compared with the losses by cinders collecting in the front- 
 end, increase as the rate of combustion increases. Thus in 
 Test No. 2, the stack losses are less than half the total loss; 
 while for Test No. 7 they constitute more than two-thirds the 
 total loss. The results of Tests, Nos. 2, 3, and 4 are of 
 especial interest, since they were run under conditions which 
 gave very nearly identical rates of combustion and served as a 
 check one upon the other. Test No. 5 shows a cinder-loss 
 
CINDERS ^ND SPARKS. 
 
 29 
 
 relatively higher than that of either Tests Nos. 6 or 7. This, 
 while unexpected, may possibly be accounted for by the fact 
 
 saisinod 
 
 that this was a high-speed test. The draft of 3.57 inches re- 
 sulted from exhaustive pulsations so rapid as to give great 
 steadiness to the outflowing jet of steam. 
 
3 LOCOMOTIVE SPARKS. 
 
 Test No. 6 should be compared with Test No. 3 rather 
 than with Test No. 5, since Test No. 3 has the same speed; 
 while Test No. 5, as already noted, was run with a much 
 higher speed. The smaller values given for Test No. 6, as 
 compared with those derived from the preceding, if not the 
 result of inaccuracies, must be due to the fact that the cut-off 
 for this test was considerably increased as compared with that 
 of all the preceding tests ; the result being that while the draft 
 was stronger and while more coal was burned, it did not have 
 the same effect upon the fire as that produced by the sharper 
 and shorter blast. However, the data is not sufficient to be 
 conclusive upon this point. 
 
 Test No. 7 was run under a long cut-off with the throttle 
 partly closed and at a slow speed, the conditions being such 
 as to give a very strong exhaust-action. The draft was 
 greater than for any of the preceding tests and more coal was 
 burned per unit of time. The weight of cinders caught in the 
 front-end is not greatly in excess of the weight of the pre- 
 ceding tests, and is even less than for Test No. 5, but the 
 weight of sparks passing out of the stack is greater than for 
 any other test; the strong blast evidently tending to clear the 
 front-end of a portion of the accumulation which otherwise 
 would have lodged there. 
 
 In conclusion, it should be noted that the value of the fuel- 
 loss by sparks and cinders, while depending chiefly upon the 
 rate of combustion, is affected also by the character of the 
 exhaust which in turn is dependent upon the cut-off and speed. 
 As these losses increase, the relative proportion of the whole 
 escaping by the stack increases ; a result which may in part be 
 due to the limited capacity of the front-end and to a more 
 perfect scouring action arising from the stronger currents 
 within it. 
 
CINDERS AND SPARKS. 
 
 As already noted, the results thus far discussed were 
 obtained in connection with Brazil block coal, a coal which 
 being light and rather friable, lends itself to the production of 
 a rather high percentage of sparks and cinders. Later investi- 
 gations made at Purdue in connection with five different 
 samples of bituminous coal submitted by the Big Four Rail- 
 road gave results which are of interest in this connection. 
 
 The apparatus used and the methods employed were essen- 
 tially the same as those described in the preceding test. 
 
 Values of the spark-losses for each of the several samples 
 of coal tested are presented in Table II. 
 
 TABLE II.* 
 
 SHOWING WEIGHT OF CINDERS AND SPARKS FROM THE 
 PURDUE LOCOMOTIVE, SCHENECTADY NO. 2, WHEN 
 USING FIVE DIFFERENT GRADES OF COAL. 
 
 
 "3. 
 
 
 
 
 "3 
 
 S'Su 
 
 Si' 
 
 "y 
 
 
 J2 
 
 A *o 
 far. 
 
 umber. 
 
 1 
 
 o 
 a 
 
 
 
 ll 
 
 .bjCU 
 
 I 
 
 S 
 
 s 
 
 c . 
 
 i 
 
 = 
 
 osition of Reverse 
 Lever. Notches 
 forward of Centn 
 
 CO 
 
 1 
 
 C u 
 
 otal Pounds of Co 
 Fired per Hour. 
 
 III 
 
 Ifsg 
 
 ounds of Water 
 Evaporated per 
 Square Foot of H 
 ing Surface per H 
 
 ounds of Sparks 
 Passing out of St 
 per Hour. 
 
 ijj 
 
 otal Pounds of 
 Cinders and Spar 
 per Hour. 
 
 atio of Total Weij 
 of Cinders and 
 Sparks to Weight 
 Coal Fired 
 
 fe 
 
 Q 
 
 C/5 
 
 OH 
 
 Q 
 
 H 
 
 cu 
 
 cu 
 
 PH 
 
 & 
 
 H 
 
 
 
 I. 
 
 II. 
 
 III. 
 
 IV. 
 
 V. 
 
 VI. 
 
 VII. 
 
 VIII. 
 
 IX. 
 
 X. 
 
 XI. 
 
 XII. 
 
 i 
 
 E. 
 
 15 
 
 5 
 
 i-5i 
 
 685 
 
 40.30 
 
 4-53 
 
 14.90 
 
 20.97 
 
 35-87 
 
 .053 
 
 2 
 
 E. 
 
 50 
 
 2 
 
 5-13 
 
 2025 
 
 119.1 
 
 IO.O2 
 
 294-5 
 
 174.0 
 
 468.5 
 
 231 
 
 3 
 
 E. 
 
 30 
 
 8 
 
 5-73 
 
 2161 
 
 127.1 
 
 10.54 
 
 3"-4 
 
 145.8 
 
 457- 2 
 
 .211 
 
 4 
 
 D. 
 
 15 
 
 5 
 
 1.70 
 
 905 
 
 53-30 
 
 4.72 
 
 13-5 
 
 31-86 
 
 45.36 
 
 .050 
 
 5 
 
 D. 
 
 
 2 
 
 5-4 
 
 2402 
 
 141-3 
 
 9.82 
 
 289.9 
 
 124.4 
 
 4H-3 
 
 .172 
 
 6 
 
 D. 
 
 30 
 
 8 
 
 6.98 
 
 2880 
 
 169.4 
 
 II. II 
 
 448.2 
 
 "8.5 
 
 576.7 
 
 .2OO 
 
 7 
 
 C. 
 
 15 
 
 5 
 
 1.77 
 
 983 
 
 57.80 
 
 4.91 
 
 12.50 
 
 16.98 
 
 29.48 
 
 .030 
 
 8 
 
 C. 
 
 50 
 
 2 
 
 5-34 
 
 2403 
 
 141-3 
 
 9-95 
 
 198.7 
 
 127.3 
 
 3 2 6.5 
 
 .136 
 
 9 
 
 C. 
 
 30 
 
 8 
 
 5-74 
 
 2606 
 
 153-3 
 
 10.24 
 
 253-4 
 
 124.6 
 
 378.0 
 
 -145 
 
 10 
 
 A. 
 
 15 
 
 5 
 
 1.70 
 
 782 
 
 46.00 
 
 4.78 
 
 16.20 
 
 28.40 
 
 44.60 
 
 57 
 
 ii 
 
 A. 
 
 5 
 
 2 
 
 5-67 
 
 2045 
 
 120.3 
 
 9.87 
 
 208.6 
 
 I2O.O 
 
 328.6 
 
 .l6l 
 
 12 
 
 A. 
 
 
 8 
 
 6.32 
 
 2364 
 
 J 39-' 
 
 iQ-34 
 
 208.9 
 
 149.6 
 
 358.5 
 
 .151 
 
 13 
 
 B. 
 B. 
 
 15 
 
 So 
 
 5 
 
 2 
 
 1.89 
 5.67 
 
 831 
 2235 
 
 48.90 
 132.0 
 
 4.76 
 9-90 
 
 10.60 
 236.1 
 
 24-95 
 126.4 
 
 362.5 
 
 .040 
 .162 
 
 '5 
 
 B. 
 
 3 
 
 8 
 
 6.40 
 
 2491 
 
 146.5 
 
 10.70 
 
 3I3-8 
 
 133-4 
 
 447.2 
 
 .ISO 
 
 * Compiled from a paper on " Tests of Coal for Locomotives," by William Garstang, Supt. 
 of Motive Power C. C. C. & St. L. R. R. Proceedings of Western Railway Club, Dec. $ 
 
LOCOMOTIVE SPARKS. 
 
 The results show that when the boiler was worked under 
 conditions which gave an evaporation of about 5 pounds of 
 water per square foot of heating-surface per hour, 5.2 per cent 
 of sample E was lost in the form of sparks and cinders; also, 
 that 5 per cent of sample D was lost from the same cause, and 
 so on. When the rate of evaporation was about 10, the losses 
 by sparks amounted to 22.1 per cent and 18.6 per cent cf 
 samples E and D, respectively. It is significant that, with one 
 exception, those samples giving the highest evaporation also 
 gave the largest spark-losses. Two conditions probably 
 account for this fact. First, the purer coals have a lower 
 specific gravity and, hence, respond to the draft-action more 
 easily than coals intermixed with non-combustible matter ; 
 secondly, in general, the lighter the ash, the larger the per- 
 centage of ash which, instead of falling through the grate, 
 passes out with the sparks and adds its mass to thfeir weight. 
 
 TABLE III. 
 
 SHOWING CHEMICAL ANALYSIS OF SPARKS FROM THE 
 PURDUE LOCOMOTIVE, SCHENECTADY NO. 1, WHEN 
 USING BRAZIL BLOCK COAL. 
 
 
 b| 
 
 ^ o 
 
 
 Composition of Sparks.* 
 
 it 
 
 SS?.! 
 
 tr. ^ 
 
 |Q 
 
 umber. 
 
 otal Pounds of I 
 Coal Fired per I 
 
 ounds of Dry Cc 
 per Square Foe 
 Grate-surface p 
 Hour. 
 
 S--I 
 
 cAgE 
 
 lit 
 
 er Cent of 
 Fixed Carbon. 
 
 o 
 
 Iff 
 
 er Cent of 
 Combined 
 Moisture. 
 
 5 M 
 u^ 
 i'o 
 
 ounds of Dry C 
 Equivalent to S 
 losses per Hour. 
 
 Q i;? 
 
 "S^Jo 
 
 I-SU 
 
 
 
 h 
 
 Cu 
 
 CH 
 
 OH 
 
 & 
 
 Pu, 
 
 
 cu 
 
 2U 
 
 > 
 
 I. 
 
 II. 
 
 III. 
 
 IV. 
 
 V. 
 
 VI. 
 
 VII. 
 
 VIII. 
 
 IX. 
 
 X. 
 
 XI. 
 
 i 
 
 1,074 
 
 61 
 
 61.5 
 
 61.74 
 
 4.36 
 
 1.82 
 
 32.08 
 
 46 
 
 75 
 
 4 3 
 
 2 
 
 1,078 
 
 84 
 
 95-i 
 
 64.88 
 
 4 .i6 
 
 1.82 
 
 29.14 
 
 77 
 
 .81 
 
 7 2 
 
 3 
 
 i, 086 
 
 124 
 
 128.6 
 
 71.32 
 
 3.45 
 
 1.66 
 
 23.57 
 
 in 
 
 .86 
 
 10.2 
 
 4 
 
 1,038 
 
 241 
 
 ^76.3 
 
 76.44 
 
 3-29 
 
 1.86 
 
 18.41 
 
 161 
 
 9I 
 
 T 5 5 
 
 * All chemical analyses were made by Charles D. Test, A.C., under the direction of Dr. 
 W. E. Stone. 
 
CINDERS AND SPARKS. 
 
 33 
 
 13. Heating Value and Coal Equivalent of Sparks. An 
 
 analysis of sample sparks obtained under different rates of 
 
 SaVdS JO QNnOd 3NO OJ. 
 3mVA ONI1V3H Nl lN31VAinS)3 "WOO dO SaNOOd 
 
 combustion when using Brazil block coal is presented in 
 Table III. 
 
 Among the significant facts disclosed by this table is that 
 
34 
 
 LOCOMOTIVE SPARKS. 
 
 relating to the varying fuel-value of the sparks. Thus the 
 sparks which result from a rate of combustion of 61 pounds of 
 coal per square foot of grate per hour are composed of one-third 
 ash, while those which were obtained under a rate of combus- 
 tion of 241 pounds have less than one-fifth their bulk composed 
 of ash; in other words, as the weight of sparks increases, their 
 fuel-value increases. 
 
 From the facts given in Table III, the relationship between 
 the rate of combustion and the fuel-value of sparks resulting 
 may be established. Such a relationship is shown by Fig. 8, 
 which shows the fraction of a pound of coal that is the 
 equivalent of a pound of sparks, which may result from different 
 rates of combustion. By use of this curve an estimate of the 
 value of the spark- and cinder-losses for the seven tests pre- 
 
 TABLE IV. 
 
 SHOWING HEATING VALUE OF SPARKS FROM THE PURDUE 
 LOCOMOTIVE, SCHENECTADY NO. 1, WHILE USING BRAZIL 
 BLOCK COAL. 
 
 
 
 
 
 
 
 
 > -a 
 
 
 
 
 
 
 J 
 
 
 ^ 
 
 \J **^ 
 
 
 3 c 
 
 .~ V- 
 
 
 
 
 j jj 
 
 "o 
 
 
 
 -^s. 
 
 > 3 
 
 III 
 
 log . 
 
 en 
 
 rt 
 
 1 
 
 (A 
 
 l|5 
 
 en 
 
 1 
 
 u 
 
 ^ 
 -3- 
 
 -^fc^ 
 J^ 
 
 
 
 < 
 
 a u 
 
 SJ| 
 uso^ 
 
 g||| 
 
 3,0 
 
 "O 
 
 **- u 
 
 g 
 
 lii 
 
 a 
 
 C 
 
 Is. 
 
 <*H rt 3 
 C 3 t" 
 
 o a 
 
 
 +- c O v. 
 
 f s 
 
 1 
 
 3 
 
 c o 
 
 it 
 
 IsJ 
 
 .ssj 
 
 X,T3 
 W 
 
 rt .- 
 
 0^ 
 
 CT 1 
 
 Isis 
 
 aOE 
 
 ll 
 
 o'rt^' o 
 
 1 g-s 
 
 111 
 
 
 o. 
 to 
 
 04 
 
 Q"" 
 
 H 
 
 CH 
 
 H^ 
 
 
 fe 
 
 CX 
 
 L 
 
 II. 
 
 III. 
 
 IV. 
 
 V. 
 
 VI. 
 
 VII. 
 
 VIII. 
 
 IX. 
 
 X. 
 
 I 
 
 15 
 
 I 
 
 i-93 
 
 79^-5 
 
 45-23 
 
 34-20 
 
 .665 
 
 22.7 
 
 2-9 
 
 2 
 
 35 
 
 I 
 
 2.98 
 
 1464.8 
 
 83.70 
 
 104.4 
 
 .801 
 
 83.6 
 
 5.7 
 
 3 
 
 35 
 
 I 
 
 3.02 
 
 15I3-6 
 
 86.50 
 
 96.00 
 
 .807 
 
 77-5 
 
 5-i 
 
 4 
 
 35 
 
 I 
 
 3.00 
 
 I557-I 
 
 88.98 
 
 108.4 
 
 .812 
 
 88.0 
 
 5-7 
 
 5 
 
 55 
 
 I 
 
 3-57 
 
 1884.4 
 
 107.68 
 
 284.7 
 
 .841 
 
 239-4 
 
 12.7 
 
 6 
 
 35 
 
 3 
 
 4.88 
 
 2017.7 
 
 115.29 
 
 177-3 
 
 .851 
 
 150.9 
 
 7-5 
 
 7 
 
 15 
 
 9 
 
 4.99 
 
 2I2I.O 
 
 121.20 
 
 293-5 
 
 .856 
 
 251.2 
 
 ii. 9 
 
CINDERS AND SPARKS. 35 
 
 viously under consideration may be had. Such an estimate in 
 terms of equivalent weight of coal is shown in Table IV. 
 
 The values given in Column VIII of this table (Table IV) 
 were taken directly from the curve in Fig. 8. Those in Column 
 IX were obtained by multiplying the values in Columns VII 
 and VIII. The values in Column X were obtained by dividing 
 100 times the values in Column IX by the values in Column V. 
 
 It will be seen that the spark- and cinder-losses measured 
 in terms of the equivalent weight of coal are, for the test for 
 which the power was lightest, equivalent to 22.7 pounds per 
 hour and for the test for which the. power was highest, 251.2 
 pounds per hour; these values being equivalent to 2.9 per cent 
 and 11.9 per cent of the weight of coal fired respectively. 
 
 Too much emphasis cannot be given the fact that these 
 results were derived while the engine was working under con- 
 ditions that are in no wise exceptional and the fact that they 
 show that more than 1 3 per cent of the fuel which passes the 
 furnace-door may completely pass the heating-surface of the 
 boiler unconsumed, h one which should merit attention. 
 
 It has already been shown that the size of the sparks varies 
 with the extent of the spark-losses. It should now be evident 
 that under low rates of combustion, the solid matter discharged 
 from the top of the stack consists of a very fine, almost sooty 
 deposit, having a very low fuel-value, while as the volume of 
 sparks is increased, the size of individual particles becomes 
 greater and their fuel-value is also increased. 
 
 14. Conclusions as to Cinder- and Spark-losses. The 
 results of the investigations herein referred to and in part 
 described, justify the following general conclusions : 
 
 1. Sparks are composed of partially consumed coal and 
 ash. 
 
 2. The total weight of cinders and sparks passing the heat- 
 
36 LOCOMOTIVE SPARKS. 
 
 ing-surface of the boiler of a locomotive increases as the rate 
 of combustion is increased, and under conditions approaching 
 maximum production may, in connection with narrow fire- 
 boxes, equal 20 per cent of the weight of coal fired. 
 
 3. Other things being equal, it is likely that the condition 
 of the fire and the character of the exhaust have considerable 
 influence upon the weight of cinders produced. 
 
 4. The fuel-value of a unit weight of sparks or of cinders 
 increases as the volume discharged increases. 
 
 5. The relation between the weight of cinders deposited in 
 a long front-end and the weight of sparks discharged from the 
 top of the stack is not clearly defined by the experiments, 
 since in general it must be a function of the length of the test 
 and of the carrying capacity of the front-end, but under high 
 rates of combustion it appears that the weight discharged from 
 the top of the stack is in excess of that from the front-end. 
 
 6. The size of sparks varies with the amount produced. 
 Thus, when conditions are such as result in small spark-losses, 
 the sparks themselves are insignificant in size, while the 
 reverse conditions result in increased size of sparks. 
 
 7. A coal burning to light ash gives a higher spark-loss 
 than one burning to clinker. 
 
CHAPTER IV. 
 SPARK-PREVENTION FRONT-END ARRANGEMENTS. 
 
 15. Spark-prevention. The problem of spark-prevention 
 is beset with difficulties. To secure the high rates of combus- 
 tion which are necessary in locomotive service, there must be 
 a free passage for air and for the products of combustion from 
 the grate to the top of the stack. Anything which may be 
 interposed in the currents of gases moving along this course 
 affects the draft and generally interferes with its action. To 
 employ obstructions which will serve in suppressing all escape 
 of sparks from the stack would choke the draft and make the 
 locomotive inoperative. In the practical working out of the 
 whole problem, therefore, spark-prevention is considered as 
 constituting but one of several factors, freedom of draft and its 
 uniform action over the whole area of the grate constituting 
 other and equally important factors. Thus it is that so-called 
 spark-arresters are inseparably connected with draft appliances 
 and that both together go to make up the front-end arrange- 
 ment. Again, the construction of the furnace may affect the 
 volume of sparks produced, the presence of a brick arch usually 
 operating to reduce spark production. 
 
 16. Increased Grate-area. Where a given quantity of 
 fuel is to be burned, the effect of increasing the grate-area is 
 to lower the rate of combustion per foot of grate-surface. 
 This means that the volume of air which, in passing a smaller 
 grate, would flow in strong currents, will, when distributed 
 
 37 
 
38 LOCOMOTIVE SPARKS. 
 
 over the area of a larger grate, flow much less rapidly. 
 Hence, it may be said that increasing the grate-area diminishes 
 the intensity of the draft-action upon the fire. With a less 
 energetic draft-action, the production of sparks is necessarily 
 reduced. Obviously, the grate cannot be regarded as a spark- 
 arrester, but since the grate is the source from which sparks 
 arise, and since when other things remain the same, an 
 increase in its area, diminishes the volume of sparks produced, 
 its proportions are not to be omitted in a consideration of the 
 general subject of spark-prevention. 
 
 17. The Brick Arch. The form of the brick arch and its 
 location within the fire-box is well shown by Fig. 9 which is 
 a vertical section of the furnace end of a locomotive boiler. 
 In the case illustrated the arch is supported upon studs or 
 brackets in the side-sheets of the furnace and extends from the 
 front-sheet obliquely backward. By its presence the length 
 of flame-way is increased and particles of fuel leaving the grate 
 are thereby held in suspension for a longer time before entering 
 the tubes, the result being that particles which would otherwise 
 be sparks or cinders are in many cases completely burned to 
 ash. The arch, also, serves to distribute the draft over the 
 grate and in so doing it doubtless contributes to the efficiency 
 of the furnace-action. 
 
 From the furnace the sparks pass directly to the front-end, 
 and it is here that provision for receiving them is chiefly pro- 
 vided. 
 
 18. A Typical Front-end arrangement, as used on 
 Schenectady No. 2, the experimental locomotive at Purdue 
 University, is shown in Fig. 10. 
 
 The exhaust-steam from the cylinders passes through the 
 exhaust-ports into the exhaust-pipe, E. From E it passes 
 through the exhaust-tip, /, and is directed upwards through 
 
SPARK-PREVENTION FRONT-END ARRANGEMENTS. 39 
 
 the petticoat-pipes, P, and out by the stack, 5. This action 
 produces a partial vacuum in the smoke-box, in response to. 
 which a current of hot gases is induced in the tubes T. The 
 hot gases finding their exit from the tubes are at once inter* 
 
 FIG. 9. 
 
 cepted by the diaphragm, or baffle-plate, D, by which they 
 are deflected downwards, as shown by the arrows. The 
 diaphragm begins above the top row of tubes and extends 
 obliquely downwards terminating in a variable slide, V, which 
 may be raised or lowered through a considerable range to meet 
 the varying conditions of service. 
 
4 LOCOMOTIVE SP4RKS. 
 
 Beyond the diaphragm is the netting, N, which divides the 
 smoke-box into a lower and an upper chamber. The door, 
 (7, is interposed in the netting to give access to the upper 
 
 FIG. 10. 
 
 chamber. Above the netting are, or may be, petticoat-pipes, 
 /*, though in many locomotives they are entirely omitted. 
 Above the petticoat-pipes is the stack, 5. At //"is a cylindrical 
 extension (not shown) which is known as the cinder-pocket, 
 
SPARK-PREVENTION FRONT-END ARRANGEMENTS. 41 
 
 through which the cinders collecting in the front-end may be 
 removed. The course, therefore, of the gases passing under 
 the diaphragm is through the netting, in and around the petti- 
 coat-pipes, where they mingle with the jet of exhaust-steam 
 and thence out through the stack. It will be seen that a spark 
 which is to pass out at the top of the stack is first met as it 
 emerges from the tubes by the diaphragm against which it 
 impinges. From the diaphragm it is deflected downward, and 
 after passing the narrow opening below the diaphragm it rises 
 to the netting. If it is very small it may at once pass the 
 netting. If it is large it will be churned about in the front- 
 end and hammered against the netting until it is sufficiently 
 pulverized to go through. It is by this process that particles 
 which otherwise would be discharged as live sparks have all 
 the fire hammered out of them before they reach the top of 
 the stack. A detailed description of the several elements 
 entering into the construction of the front-end is as follows: 
 
 19. Diaphragm or Baffle-plate. The function of the 
 diaphragm is twofold. First, it acts as a deflector to throw 
 the solid particles away from the point of strongest exhaust- 
 action, and to break up large particles which impinge against 
 it. Secondly, it acts as draft-regulating device. If the dia- 
 phragm were absent, the upper rows of tubes, owing to their 
 proximity to the exhaust-jet, would be affected by the exhaust- 
 action more than the lower tubes. The diaphragm acts as a 
 shield to the upper tubes, checking the draft action in them 
 and, by so doing, augmenting the current in the lower 
 tubes. If the draft is not well distributed in the tubes, 
 the fuel burns unevenly and the steaming-action of the 
 boiler is impaired. Mr. C. H. Quereau* gives the follow- 
 
 * Report to International Railway Congress, Paris, 1900. 
 
LOCOMOTIVE SPARKS. 
 
 ing as present American practice (1900) in the design and 
 arrangement of the diaphragm : 
 
 FIG. ii. 
 
 "Fig. ii shows the types of diaphragms generally used. 
 Arrangement a, with the plates back of the exhaust-pipe, is 
 standard with eighteen roads ; arrangement /;, with the plates 
 extended forward of the exhaust-pipe, is standard with nine 
 
SPARK-PREYENTION FRONT-END ARRANGEMENTS. 43 
 
 roads. Arrangement b sweeps the cinders from the front-end 
 so that it is not necessary to clean them either on the road or 
 at terminals, and the cinder-hopper, with the chances of its 
 leaking, are done away with. Two roads use the arrangement 
 shown in c. What its special advantage is does not appear. 
 Another arrangement of two plates is illustrated by d, which 
 is used by two roads on boilers which are larger than 62 inches 
 in diameter at the forward ring. With boilers of this size it is 
 frequently difficult to distribute the draft uniformly over the fire 
 and at the same time properly clean the cinders from the front- 
 end. Design d does this admirably." 
 
 ' ' There has been little change in the general design of the 
 diaphragm since 1890. Three roads have moved their plates 
 from in front of the exhaust-pipe to back of it, and three have 
 reversed this. One road writes as follows : ' The only change 
 we have made since 1 890 has been to put the diaphragm back 
 of the exhaust-pipe and steam-pipes to overcome the excessive 
 wear of these pipes. We also find the change has promoted 
 combustion.' 
 
 "It is the almost universal custom to use an adjustable 
 plate on the fixed plate with which to change the distance from 
 the bottom edge of the diaphragm to the bottom of the front- 
 end and in this way distribute the draft evenly over the flues 
 and grate. " 
 
 20. Netting. The purpose of the netting is to prevent 
 particles of fuel from passing out of the stack in a state of 
 ignition. It must be sufficiently open to permit the furnace- 
 gases to pass freely through and to minimize the danger of its 
 filling up with smoky deposits. It must be sufficiently close 
 to prevent escape from the stack of such larger particles as are 
 likely to be in a state of ignition. 
 
44 
 
 LOCOMOTIVE SPARKS. 
 
 Thus, Mr. Quereau* reports as follows: 
 " Present practice, in so far as the general arrangement of 
 the netting is concerned, is shown in Fig. 12, from which it 
 
 FIG. 12. 
 
 appears that four roads use arrangement a and twenty-three 
 roads b. The controlling reason for the design b seems to be 
 convenience in getting at the exhaust-tip and baffle-plates, and 
 
 * International Railway Congress, Paris, 1900. 
 
SPARK-PREVENTION-FRONT-END ARRANGEMENTS. 45 
 
 an increased area of netting. Diagram c, commonly called 
 the basket-netting, is used to some extent. This is the most 
 convenient form, in so far as ease in getting at the deflector- 
 plates and steam-pipe joints is concerned, and equally as con- 
 venient as form b when it is necessary to reach the tip, but, in 
 front-ends of large diameters, form c is liable to cause an 
 accumulation of cinders in the front-end, probably because the 
 currents around each side meet in front, causing an eddy, and 
 because the currents do not strike the netting at right angles, 
 increasing the resistance." 
 
 ' ' The preference of the roads as to the material used in the 
 netting is shown by the fact that twenty use woven wire and 
 seven, perforated plates. The favorite dimensions for wire- 
 netting is that with 2-J- X 2j meshes per square inch, with the 
 wires, .12 inch in diameter, used by nine roads. Next comes 
 a netting with the same mesh, but the wire .109 inch in 
 diameter, used by five roads. Netting with meshes as fine as 
 8x8 per square inch and wire .049 inch in diameter is used 
 by one road which runs through a country specially liable to 
 fires. " 
 
 "In the perforated plates the openings are usually about 
 i X T 3 ^ mc h or i * nc k w ^ the corners filletted, with a J-inch 
 bridge between, the sheet through which the holes are punched 
 being usually \ inch thick, as shown in Fig. 13." 
 
 21. Petticoat-pipe can only be used with advantage when 
 the exhaust-nozzle is set low. In such cases it helps to dis- 
 tribute the action of the exhaust, generally permitting the 
 deflector-plate to come higher than otherwise. The result is 
 a more open, or less obstructed front-end. The petticoat-pipe 
 provides additional channels through which the gases of the 
 smoke-box are fed to the jet of steam and by so doing they 
 serve to transform the comparatively small and powerful jet of 
 
4 6 
 
 LOCOMOTIVE SPARKS. 
 
 steam into a larger but less intense stream of mixed gase.s and 
 steam. This issuing from the first petticoat-pipe becomes the 
 moving force to act upon other portions of gas; the moving 
 stream augmented in size by fresh additions enters the second 
 
 .ruuuLnJLnJLrJ 
 
 FIG. 13. 
 
 petticoat-pipe from which it issues to again repeat the process 
 before entering the base of the stack. The petticoat-pipes 
 serve to distribute the load of smoke-box gases taken up by 
 the steam-jet, and by defining the boundaries of the combined 
 jet, they prevent its losing energy by breaking up into eddies. 
 In so far as they accomplish this they contribute to the effi- 
 ciency of the exhaust-action. 
 
 As a practical matter it should be said that experience 
 proves that the adjustment of the petticoat-pipes to a proper 
 height relative to the other elements affecting the draft is a 
 very important matter. A few inches higher or lower may 
 have a decided effect on the steaming qualities of the boiler. 
 In many cases petticoat-pipes are entirely omitted and when 
 used they may be double as shown by Fig. 10, or single. 
 
 22. Exhaust-pipe. There are two forms of exhaust-pipes 
 in general use, the single and the double. In the single 
 exhaust-pipe the steam from both cylinders escapes through 
 the same tip as shown by Fig. 14. The double exhaust-pipe 
 
SPARK-PREVENTION FRONT-END ARRANGEMENTS. 
 
 47 
 
 allows the steam from each cylinder to exhaust through an 
 independent tip as shown by Fig. 15. 
 
 The object of any design or arrangement of exhaust-pipe is 
 to serve in carrying off the exhaust-steam from the cylinders 
 
 FIG. 14. 
 
 with the least amount of back pressure and at the same time 
 give a jet having sufficient energy to produce the required 
 draft. A double nozzle provides a separate exit for the steam 
 from each cylinder ; a single nozzle requires the steam from 
 both cylinders to emerge from the same opening. With the 
 sinele nozzle, however, the passages are kept separated until 
 
 OF THE 
 UNIVERSITY 
 
4 8 
 
 LOCOMOTIVE SPARKS. 
 
 the point of discharge is nearly reached. When the exhaust- 
 pipe is very short or when other details of the whole arrange- 
 ment of ports and pipes are such that, a single nozzle might 
 allow steam exhausted from one cylinder to pass into the 
 
 FIG. 15. 
 
 exhaust-passage of the other cylinder, a double exhaust-pipe 
 must be used. Under conditions such as are shown by Figs. 
 14 and 15, it is perhaps sufficient to say that good practice 
 involves both forms and that both forms have their advocates. 
 The Master Mechanics' Committee, however, recommends the 
 
SPARK-PREVEN TIONFRCN T-END ARRANGEMEN TS. 
 
 49 
 
 single pipe (Fig. 14) as the more efficient of the two arrange- 
 ments. 
 
 23, Exhaust- tip. The exhaust- tip is the fixture at the 
 end of the exhaust-pipe. It is the tip which governs the size, 
 shape, and velocity of the exhaust-jet. Exhaust-tips may, in 
 general, be either fixed or variable. Fixed tips are designed 
 to meet the average conditions of service and are of various 
 forms as shown by Fig. 1 6. 
 
 i 
 
 FIG. 16. 
 
 The variable exhaust-tips are so designed that the area of 
 the opening may be changed at the will of the engineer as the 
 conditions of service may require, or controlled by the position 
 of the reverse lever or through the action of some other part of 
 the mechanism of the engine. In theory the variable exhaust- 
 tip is correct, but the difficulties to be overcome in its design 
 and operation have thus far prevented it from coming into 
 
50 LOCOMOTIVE SPARKS. 
 
 general use in this country. For a discussion of the relative 
 merits of fixed and variable exhaust-tips as used on foreign loco- 
 motives, the reader is referred to a report by Mr. Eduoard 
 Sauvage to the International Railway Congress, Paris, 1900.* 
 
 24. Smoke-stack. The smoke-stack serves to convey the 
 gases and the exhaust-steam from the smoke-box to the outer 
 air. There are two general classes, the open stack and the 
 diamond stack. Open stacks may be straight or tapered. 
 Until quite recently they have ordinarily been straight as 
 shown by Fig. 33, but they are now generally tapered as 
 shown by Fig. 10 and by Figs. 23 to 29. The opinion is 
 prevalent that the double-tapered stack (Fig. 10) is more 
 efficient than the straight stack and it is known to be less sub- 
 ject to wear from the action of sparks. 
 
 The open stack is used in connection with the extension 
 front; the diamond-stack, in connection with the short front- 
 end. Fig. 10 is a type of the former, and Fig. 17 of the latter. 
 The diamond-stack is essentially a combination of stack and 
 spark-arrester. The solid particles of fuel impinge against the 
 cone at the top of the stack and are deflected into the bonnet, 
 If small, they may be swept out through the netting at the 
 top, but if large they are retained in the bonnet where, by the 
 repeated action of the exhaust, they are hammered about until 
 broken sufficiently to pass through the netting. 
 
 The diamond-stack is the older type of construction, and 
 while still somewhat used it is nevertheless gradually disap- 
 pearing from service. 
 
 25. Extended Front-end. The extended front-end is a 
 necessary part of the general arrangement, the details of which 
 constitute the subject of the several paragraphs immediately 
 
 * Railroad Gazette, pp. 448-450, June 29, 1900. 
 
SPARK-PREYENTION-FRONT-END ARRANGEMENTS. $1 
 
 FIG. 17. 
 
52 LOCOMOTIVE SPARKS. 
 
 preceding, but its dimensions may be varied within rather wide 
 limits. Originally it was intended to be large in order that it 
 might supply sufficient space in which cinders could be 
 entrapped. This is shown by the following statement of the 
 inventor, as quoted by Mr. Bell : * 
 
 ' ' The nature of my invention consists in extending the 
 smoke-arch or smoke-box (front-end) so far beyond the 
 chimney (stack) and the blast-pipe that the sparks and cinders 
 ejected from the stack of pipes (tubes) connecting the smoke- 
 arch (front-end) with the furnace may be thrown so far forward 
 beyond the draft or current of smoke passing from the stack 
 (the tubes) to the chimney (stack) as to fall down and settle or 
 be retained within the smoke-box. ... I have found that by 
 extending the smoke-box (front-end) some considerable dis- 
 tance, that is, about 1 8 inches or more, in manner as described 
 and represented, beyond the course of the draft, most, if not 
 all of the sparks and cinders, will pass beyond the current of 
 smoke and be deposited in the smoke-box (front-end)." 
 
 In practice it is found that while the front-end will retain 
 some sparks, it cannot hold all which would naturally accumu- 
 late except for a brief interval. This being true the difficulties 
 of freeing the front-end of its accumulation, between terminals, 
 has led to the general adoption of such proportions as will give 
 best results in the matter of draft, regardless of its capacity for 
 cinders. Data already quoted (Table III, Chapter III) show 
 that with a front-end so designed as to be capable of holding 
 large amounts of sparks, the volume passing out of the stack 
 is greater than that which is entrapped. In general, therefore, 
 it may be said that the front-end of to-day serves the purpose 
 of providing room for a liberal area of netting. It is not 
 regarded as of value as a means for retaining cinders. 
 
 * J. Snowden Bell before the Western Railway Club, September, 1899. 
 
SPARK-PREVENTION FRONT-END ARRANGEMENTS. 53 
 
 26. Practice in Front-end Arrangements. Thus far we 
 have considered the various details which have to do with the 
 maintenance of draft and the prevention of sparks. We may 
 now take a more general survey to ascertain what are the 
 differences which characterize present-day practice, and in so 
 doing will again have resort to the excellent paper of Mr. Bell 
 from which the following is largely abstracted and arranged. 
 
 Referring first to the diamond stack, attention is called 
 to Fig. 17, which represents the standard of the Union Pacific 
 Railway for the past fifty years, and to Figs. 18 and 19, which 
 show the adaptation of this practice to some large consolida- 
 tion engines recently built for the same road. It will be seen 
 that the smoke-box is unobstructed by either diaphragm or 
 netting, that the nozzles are low and that they have a long 
 petticoat-pipe above them. The spark-arresting is accom- 
 plished in the stack which is enormously enlarged to accomo- 
 date a sufficient area of netting and which carries an inverted 
 " cone " to baffle the sparks. Figs. 20 and 21 represent the 
 standard stack and front-end for burning wood, of the Mexican 
 Central Railroad, which differs from those already described 
 only in minor details and in the proportion of parts. 
 
 Returning now to the open stack and the extended front 
 so common in present-day practice, attention should first be 
 given the particular arrangement recommended by the Master 
 Mechanics' Committee on Exhaust-pipes and Steam-passages, 
 of 1896. The Committee made elaborate experiments and 
 established dimensions for exhaust-pipe, tip, petticoat-pipes, 
 and stack which- are believed to give maximum efficiency. 
 These are shown by Fig. 22. 
 
 While the committee recommended that the smoke-box be 
 made sufficiently long to permit a cinder-pocket or cinder-pot 
 for the discharge of cinders, to be located in front of the cylin- 
 
54 
 
 LOCOMOTIVE SPARKS. 
 
 77! 
 
 3'll"X 
 
SPARK-PRE MENTION -FRONT-END ARRANGEMENTS. 55 
 
 FIG. 19. 
 
56 LOCOMOTIVE SPARKS, 
 
 der-saddle, as shown in Fig. 25, the fact was generally recog- 
 nized that the smoke-box, whether long or short, could not, 
 and did not in practice, perform to any extent the function of 
 a cinder receptacle or retainer. 
 
 FIG. 20. FIG. 21. 
 
 In further discussion of the general subject, the Convention 
 agreed that it is possible to so arrange the front-ends of 
 locomotives that they will clear themselves of cinders without 
 throwing live sparks. (Topic No. 2, pp. 103-108, Proceed- 
 ings of 1898.) 
 
SPARK-PRE^ENTION-FRONT-END ARRANGEMENTS. 
 
 T 
 
 FIG. 22. 
 
58 LOCOMOTIVE SPARKS. 
 
 The length of the front-end was not definitely fixed by the 
 committee, though the opinion was expressed that a more 
 efficient arrangement would result if it were made shorter than 
 was then (1896) common practice. As a result of this recom- 
 mendation and of the experience of master mechanics acting 
 individually, we now find many so-called " short " front-ends, 
 though many of the long or " extended " type still remain. 
 
 The general design of the Master Mechanics' Committee, 
 as applied to an extended front-end is shown by Fig. 23. 
 The extension of the deflecting-plate in front of the exhaust- 
 pipe is for the purpose of clearing the front-end of cinders. 
 Where this arrangement is employed, the cinder-pot is dis- 
 pensed with. Fig. 24 shows a self-cleaning front as used on 
 Class U engines of the Norfolk & Western Railway. Mr. 
 W. H. Lewis, Superintendent of Motive Power of that road, in 
 writing to Mr. Bell, with reference to his design, well states 
 the considerations which have led to the adoption of self-clean- 
 ing front-ends. He writes as follows: 
 
 ' ' The self-cleaning features of these are practically the 
 same, and we have found that it is possible to do away entirely 
 with the cinder-hopper and blower, and experience no trouble 
 with the front filling with cinders." 
 
 " I beg to remind you, however, that the general rules to 
 be observed in the arrangement of these spark-arresting devices 
 are largely dependent upon the character of the coal and the 
 service performed by locomotives, and the position of the 
 deflector and diaphragm-plates can only be determined by a 
 careful service test. The satisfactory results which we are 
 now obtaining have thoroughly convinced us that it is not 
 necessary to maintain a long-extended front as a receptacle 
 for cinders, and that only sufficient extension is required to 
 insure the proper area of opening in the perforated plates or 
 
SPARK-PREVENTION FRONT-END ARRANGEMENTS. 59 
 
 FIG. 23. 
 
6o 
 
 LOCOMOTIVE SPARKS. 
 
 FIG. 24. 
 
SPARK-PREVENTION FRONT-END ARRANGEMENTS. 61 
 
 netting used to insure a free draft; in fact, in the number 
 of observations which we made prior to the adoption of the 
 device, it was found that our long-extended fronts accumulated 
 the maximum amount of cinders in a distance of ten miles, 
 in heavy mountain service, so that all of the cinders and 
 sparks which entered the front-end after that time were 
 necessarily thrown out. We, therefore, felt that little ad- 
 vantage might be expected from simply storing the cinders 
 that would accumulate in going a distance of ten miles and 
 running a further distance of fifty or sixty miles without any 
 further accumulation, and that it was thoroughly logical to 
 adopt a device which would relieve the front of cinders 
 entirely." 
 
 A front-end which in its length very nearly conforms to 
 the recommendation of the Master Mechanics' Committee is 
 shown by Fig. 25. This is from the drawings of certain classes 
 of small engines on the C. B. & Q. Railway. The general 
 arrangement disclosed by the figure may be accepted as 
 common to very many locomotives in the United States. An 
 arrangement not uncommon is shown by Fig. 26, the illustra- 
 tion being taken from a heavy Atlantic type engine of the 
 C. B. & Q. In this case the exhaust-nozzle is low and the 
 general plane of the netting high, the distance between being 
 spanned by a ' < basket ' ' form of netting. The diaphragm is 
 almost entirely absent in this design, the whole front being 
 quite free of obstruction. Another arrangement, somewhat 
 similar in principle but involving a lower deflector-plate and 
 petticoat-pipes is shown by Fig. 27. 
 
 A front-end employed on ten large engines of the Mexican 
 Central is shown by Figs. 28 and 29. It will be seen that it 
 is very short, that an extension of the deflector is brought to 
 a point forward of the nozzle, and that the netting does not 
 
62 
 
 LOCOMOTIVE SPARKS. 
 
 FIG. 25. 
 
SPARK-PREVENTION -FRONT-END ARRANGEMENTS. 6 3 
 
 FIG. 26. 
 
LOCOMOTIVE SPARKS. 
 
 FIG. 27. 
 
SPARK-PRE1SENTION-FRONT-END ARRANGEMENTS. 65 
 
 connect with the deflector, there being an unobstructed 
 space of 17 inches between them. Mr. Johnstone of the 
 Mexican Central in writing to Mr. Bell of this front-end 
 says: 
 
 "You will see that we are using the master mechanics* 
 standard nozzle and petticoat arrangement, with what we call 
 the Mexican Central standard deflecting-plate and netting 
 arrangement. This gives a clear opening between the bottom 
 of the netting and the top of the deflecting-plate of 17 
 inches." To this Mr. Bell adds that "present practice 
 in front-ends is plainly marked in the abandonment of the 
 long-extended smoke-box by the Pennsylvania railroad 
 in its latest and most approved designs of locomotives, 
 for both fast passenger and heavy freight service. Figs. 
 30 and 3 1 show the front-end arrangement of the large 
 H 5 and H 6 consolidation engines, recently built by that 
 company, and the same design, in all substantial particulars, 
 is used on their latest construction of high-speed passenger 
 engines. " 
 
 4 ' In view of the fact that this front is doubtless practically 
 self-cleaning, and of the comparatively large diameter of the 
 smoke-box, it may be suggested that it could, with advantage 
 and without sacrificing any netting area, be further shortened, 
 as, say, 10 inches or thereabouts. Again, if a cinder-pocket 
 is believed to be desirable with this or any other design of 
 front, it would seem that if its smoke-box opening were made 
 oblong, with the greater dimension transverse to the engine, 
 the free discharge of the cinders would be facilitated and the 
 length of front necessary to accommodate it be diminished. 
 Among other meritorious features of this design, attention may 
 be called to the disposition of the netting, whereby as great an 
 area as is practicable within a determined length of front is 
 
66 
 
 LOCOMOTIVE SPARKS. 
 
 FIG. 28. 
 
SPARK-PREVENTION FRONT-END ARRANGEMENTS. 67 
 
 WIRE NETTING 
 NO. 3 MESH NO. 11 WIRE 
 
 FIG. 29. 
 
68 
 
 LOCOMOTIVE SPARKS. 
 
 obtained, and the sheets are inclined relatively to the trav- 
 erse of the escaping" products of combustion. The inward 
 extension of the stack, while by no means a novel feature. 
 
 FIG. 30. 
 
 having been applied in English engines as early as 1860, is 
 also believed by the writer to be of substantial practical value. 
 There can be no doubt of the efficiency of this front, both as 
 
SPARK-PREVENTION FRONT-END ARRANGEMENTS. 
 
 69 
 
 to free steaming and prevention of fire throwing, arid it has 
 been not an unimportant factor in the phenomenal performance 
 of the E I passenger engines on the Camden & Atlantic Rail- 
 road." 
 
 FIG. 31. 
 
 The Coburn front-end, which is shown in Figs. 32, 33, and 
 34, was designed by the late Mr. W. P. Coburn, of the Chicago, 
 Indianapolis & Louisville Railway. It is designed to break up 
 the sparks into fragments so small as to be incapable of doing 
 damage, before they reach the stack. This is accomplished by 
 a suitable arrangement of deflecting plate in connection with 
 nests of long, closely set cast-iron spikes extending from the 
 front door and head, rearward into the smoke-box. The cur- 
 rent passing from the deflector-plate is sent upward into and 
 
7 o 
 
 LOCOMOTIVE SPARKS. 
 
SPARK-PREVENTION FRONT-END ARRANGEMENTS. 
 
 FIG. 35. 
 
72 LOCOMOTIVE SPARKS. 
 
 through the nests of spikes already referred to. In making 
 the passage, the cinders are made to impinge against the spikes 
 which are set in their way, and are thereby pulverized to the 
 desired degree of fineness. Obviously, this front-end is self- 
 cleaning. 
 
 "The Bell front-end as in service in 21 X 26-inch con- 
 solidation engines on the Baltimore & Ohio Railroad is shown 
 in Fig. 35. In later applications, on this road and on the 
 Pittsburgh, Bessemer & Lake Erie Railroad, an addition has 
 been made to the lower end of the deflecting-plate, extending, 
 on a slight incline to a line in front of the exhaust-pipe, on the 
 same principle as that of the self-cleaning fronts before referred 
 to. The deflecting-plate is punched, with lips projecting 
 toward the front from the holes, and a sheet of netting is placed 
 in front of it to intercept any cinders that may pass through 
 the holes. The main portion of the netting is set in three 
 planes or in ' * saw-tooth ' ' form in front of the exhaust-pipe, so 
 as to present approximately vertical surfaces to the cinders as 
 they pass up from below the deflecting-plate, and a i-inch 
 clear opening, protected by a lower sheet of netting, is left 
 between the two front inclined sheets to prevent clogging by 
 accumulation of cinders between them." 
 
 27. Authorities on the Front-end. Those who may wish 
 to make a more extended study of front-end arrangements will 
 find an abundance of material. If interested in the proportions 
 which give maximum efficiency to details of usual form, they 
 should become familiar with the results of the very elaborate 
 series of experiments which will be found of record in the 
 Report on Exhaust-pipes and Steam-passages, Proceedings of 
 the Master Mechanics' Association, 1896. These experiments 
 were broadly planned and faithfully executed under the direc- 
 tion of Mr. Robert Quayle, Chairman of the Committee, 
 
SPARK-PREVENTION FRONT-END ARRANGEMENTS. 73 
 
 assisted by Mr. E. M. Herr. The work was made to involve 
 a full-sized locomotive so arranged that the desired data could 
 be obtained with a degree of accuracy which inspires confi- 
 dence in the general conclusion formulated by the committee. 
 Another elaborate series of experiments designed to serve the 
 same end, but involving quite a different plan of procedure, was 
 conducted under the direction of Herr von Borries and 
 Inspector Troske of the Prussian State Railway. An account 
 of these experiments, translated from the German, was pub- 
 lished in this country as a series of articles by the American 
 Engineer. These appeared in ten of the twelve issues for the 
 year 1896. 
 
 In his report on Draft Appliances to the International 
 Railway Congress, Paris, 1900, Mr. C. H. Quereau reviews 
 both the work of the Master Mechanics' Committee and the von 
 Borries-Troske experiments and gives in condensed form the 
 conclusions which they justify. 
 
 Those who are more interested in different combinations of 
 the details should read a paper entitled " Draft Appliances of 
 the Locomotives Exhibited at the Columbian Exposition, 
 Chicago," which was read by Mr. E. M. Herr before the 
 November, 1893, meeting of the Western Railway Club ; also 
 a paper, " Locomotive Front-ends," by J. Snowden Bell, given 
 before the Western Railway Club ; and in this connection, 
 also, Mr. Quereau's report to the International Railway Con- 
 gress to which reference has already been made. 
 
CHAPTER V. 
 
 ACTION OF THE EXHAUST-JET AND DISTRIBUTION OF 
 SPARKS WITHIN THE FRONT-END. 
 
 28. Experiments to Determine the Character of the 
 Exhaust-jet. The action of the exhaust-jet, and the design 
 and arrangement of the draft appliances, have, as previously 
 noted, been carefully investigated by a committee of the 
 American Railway Master Mechanics' Association.* That 
 part of the work which related to the action of the exhaust-jet 
 was carried on at the locomotive laboratory of Purdue Uni- 
 versity by methods which may be described as follows : 
 
 In line with the centre of the stack and exhaust-pipe, cast- 
 iron sleeves were fastened to the outside of the smoke-box 
 (Fig. 36). Through these were fitted pipes I, 2, 3, 4, and 5, 
 arranged to slide in and out across the smoke-box, and having 
 their inner ends turned down to a fine tip with sharp edges 
 bounding the orifices. The body of each pipe was graduated 
 to tenths of inches, the scale reading from a reference-mark 
 fixed to the sleeve on the outside of the smoke-box. If the 
 zero of the scale were Drought under the reference-mark, the 
 inner edge of the pipe would be directly under the centre of 
 the stack, and directly over the centre of the exhaust-pipe. 
 It is obvious that if the tip of any pipe be surrounded by the 
 
 * Report on Exhaust-pipes and Steam-passages, Master Mechanics'' 
 Proceedings, 1896. pp. 58-143. 
 
 74 
 
ACTION OF THE EXHAUST-JET. 75 
 
 jet of exhaust-steam, the velocity of the latter will tend to 
 carry steam through the pipe and to discharge it into the 
 atmosphere outside of the smoke-box. It can be shown also 
 that the force which the steam would exert in its effort to pass 
 the pipe is a function of its velocity; hence by observing the 
 force or pressure the velocity may be calculated. Pressures 
 were observed by having the outer ends of each sliding pipe 
 connected by rubber tubing with one leg of a manometer or 
 U-shaped glass tube which was fastened to the wall of the 
 laboratory. These U tubes were partially filled with mercury, 
 the displacement of which gave the pressure transmitted 
 through the tube. If, for example, the tip of any particular 
 pipe were in the jet of steam, its manometer would show pres- 
 sure ; if it were withdrawn from the jet, its manometer would 
 indicate a vacuum. 
 
 Besides these sliding pipes in the smoke-box, the stack 
 was fitted with three pipes which had plain ends projecting 
 beyond the inner wall about a quarter of an inch. These side 
 orifices were each connected with a manometer. They served 
 to show the extent of pressure or vacuum existing within the 
 stack at points where they were attached. Their exact loca- 
 tion is shown by the dimensions in Fig. 36. 
 
 The draft was measured by two different manometers, and 
 was permanently registered by a Bristol recording-gage. 
 Indicators were used to show the steam distribution in the 
 cylinders, and a special indicator fitted with a light spring gave 
 a fine record of the back-pressure line. This pressure was also 
 recorded by a Bristol gage. A Boyer speed-recorder served 
 as a means for maintaining constant speed conditions. 
 
 Observations were made as follows : Desired conditions of 
 speed and steam-pressure having been obtained, the adjustable 
 pipes (i, 2, 3, 4, and 5), Fig. 36, were withdrawn from the 
 
76 LOCOMOTIVE SPARKS. 
 
 smoke-box sufficiently to bring them entirely clear of the 
 exhaust-jet, usually to a distance of 4! inches from centre of 
 jet. Then, upon signal, all manometer-gages were read and 
 all other observations taken, the readings being taken simul- 
 taneously. Each sliding pipe was then moved inward a tenth 
 of an inch and readings repeated, after which they were moved 
 another tenth, and so on until the tips of all the pipes reach the 
 centre of the exhaust-jet. The readings thus obtained from 
 the pipes 1,2, 3, 4, and 5, Fig. 36, were entered upon a 
 half-sized drawing representing a portion of the cross-section 
 of the smoke-box, the position of each entry showing the exact 
 location to which the numerical readings applied. Upon the 
 diagram of pressures thus obtained lines were drawn through 
 points showing neither vacuum nor pressure. These lines 
 were assumed to represent the border of the steam-jet, and are 
 the outside lines in Figs. 37 to 39. In a similar manner, lines 
 were drawn inside of those just described, each line connecting 
 points representing the same pressure. These also appear in 
 Figs. 37 to 39, but the numbers given in connection therewith 
 do not represent pressure, but velocity in feet per second, as 
 calculated from the indications of the gages. Each line, there- 
 fore, represents a chain of particles which have the same 
 velocity, the value of which, in feet per second, is shown by 
 the figure attached thereto. 
 
 The three jets thus shown were obtained under the same con- 
 ditions, except that the speed of the engine for Fig. 37 was 25 
 miles; for Fig. 38, 35 miles, and for Fig. 39, 45 miles per hour. 
 The conditions of running were such that each increment of 
 speed resulted in a larger volume of steam delivered, and con- 
 sequently in a higher vacuum. The diagrams show that as 
 the volume of steam delivered increases, the velocity of the 
 jet increases and its spread diminishes, due, doubtless, to the 
 
ACTION Of THE EXHAUST-JET. 
 
 77 
 
 FIG. 36. 
 
7* LOCOMOTIVE SPARKS. 
 
 reaction of the body of smoke-box gases surrounding the jet. 
 The velocity curves which in Fig. 38 are pretty evenly dis- 
 tributed throughout the body of the jet are in Fig. 39 crowded 
 together, giving evidence in the latter case of a very dense and 
 powerful jet. 
 
 The results derived from a large number of experiments 
 similar in nature to that just described will be found presented 
 
 MILES PER HOUR 25 
 
 REVOLUTIONS PER MINUTE 135 
 
 POUNDS CF STEAM PER HOUR 6090 
 
 MILES PER HOUR 
 
 REVOLUTIONS PER MINUTE T88/ 
 
 POUNDS OF STEAM PER HOUR 8122^, 
 
 MILES PER HOUR 43 
 
 REVOLUTIONS PER MINUTE 242 
 
 POUNDS OF STEAM PER HOUR 8670 
 
 FIG. 37. 
 
 FIG. 38. 
 
 FIG. 39. 
 
 in the Proceedings which have been referred to. From their 
 study the following conclusions concerning the action of the 
 jet appear to have been justified. 
 
ACTION OF THE EXHAUST-JET, 79 
 
 29. The Action of the Exhaust-jet. Previous to the 
 experiments just described it had usually been assumed that 
 the action of the exhaust-jet is similar to that of a pump ; that 
 each exhaust supplies a ball of steam, which fills the stack 
 A^ery much as the piston of a pump fills its cylinder, and which 
 pushes before it a certain volume of the smoke-box gases until 
 it passes out at the top of the stack. The experiments dis- 
 prove this theory. They show that the jet of steam does not 
 fill the stack at or near the bottom ; that under certain condi- 
 tions common to practice it touches the stack only when it is 
 very near the top; and, finally, that a jet of steam flowing 
 steadily from the exhaust-tip, the engine being at rest, results 
 in draft conditions which are in every way similar with those 
 obtained with the engine running, the same amount of steam 
 being discharged per unit of time in each case. 
 
 Enough has not yet been done to define the precise action 
 of the jet, but it may be said with certainty (i) that it acts to 
 induce motion in the particles of gas which immediately sur- 
 round it, and also (2) that it acts to enfold and entrain the 
 gases which are thus made to mingle with the substance of the 
 jet itself. 
 
 The induced action, which, for the jets experimented upon, 
 is by far the most important, may be illustrated by means of 
 Fig. 40. The arrows in this figure represent, approximately, 
 the direction of the currents surrounding the jets. It will be 
 seen that the smoke-box gases tend to move toward the jet, 
 and not toward the base of the stack, at which point they are 
 to leave the smoke-box. That is, the jet, by virtue of its high 
 velocity and by its contact with surrounding gases, gives 
 motion to particles close about it, and these, moving on with 
 the jet, make room for other particles which are farther away. 
 As the enveloping shell of gas approaches the top of the stack, 
 
So 
 
 LOCOMOTIVE SPARKS. 
 
 FIG. 40. 
 
ACTION OF THE EXHAUST-JET. Si 
 
 its velocity increases and it becomes thinner and thinner, all 
 as shown by Fig. 40. All parts of the jet require gases to 
 work upon the upper as- well as the lower part. Gages 
 attached to the side of the stack show a vacuum, because the 
 gases needed for the upper portion of the jet can reach it only 
 by coming in around the jet lower down. In other words, the 
 action of the upper part of the jet induces a vacuum in the 
 lower part of the stack, just as the action of the jet as a whole 
 induces a vacuum in the smoke-box. It will be shown later 
 that as the amount of work to be done by the exhaust is 
 increased the jet becomes smaller, thus making room for 
 larger volumes of gas to pass between it and the stack ; the 
 velocity both of the jet and of the induced currents increasing. 
 
 The Intermingling of tJie Smoke-box Gases ivit/i tJie Steam. 
 That there is some intermingling of the smoke-box gases with 
 the steam of the jet is made evident by the appearance of the 
 combined stream as it issued from the top of the stack. The 
 manner in which this intermingling takes place will be seen 
 from the following considerations. 
 
 Any stream flowing from a nozzle through a resisting 
 medium will have a higher velocity at its centre than at its 
 circumference or sides. That is, the particles at the centre of 
 the jet move at a higher velocity than those on the outside, the 
 latter being held back by contact with the surrounding gas. 
 The result of the different velocities in the same stream is a 
 wave motion of the individual particles of which the stream is 
 composed. Thus the path of any one of these particles may 
 be shown by Fig. 41, A, but the exact form and frequency of 
 the loops will depend upon the relation between these differ- 
 ences in the velocity of particles in different portions of the 
 stream, and the actual mean velocity of the jet. If the velocity 
 of the jet is high, and differences for different portions of the 
 
LOCOMOTIVE SPARKS. 
 
 cross-section are not great, the loop may disappear, the path 
 appearing as shown by Fig. 41, B. With a still higher mean 
 velocity, and a smaller difference, the loops would approach 
 
 FIG. 41. 
 
 the form shown by Fig. 41, C. The exhaust-jet appears to 
 take this latter form. Measurements to determine its velocity 
 show that particles in the centre move much more rapidly than 
 those near the outside, and other measurements to determine 
 
Fio. 42. 
 
ACTION OF THE EXHAUST-JET. 85 
 
 the form of the jet as a whole, define a boundary which is 
 neither a straight line nor a regular curve, but which agrees 
 closely with the form given by Fig. 41, .C. All this shows 
 that the jet is stepped off in nodes, which under given condi- 
 tions remain fixed in position. This conclusion, based upon 
 measurements of the jet, is confirmed by the appearance of the 
 jet as seen in an engine running with the front-end open. 
 The jet when thus viewed exhibits one or more bright spots 
 which remain in a fixed position. It is through the wave action 
 of the particles making up 'the steam-jet that the surrounding 
 gases are enfolded and intermixed with the steam of the jet. 
 
 It is clear that any design of nozzle which will serve to 
 subdivide the stream, or to spread it so as to increase its cross- 
 section, will assist the jet in its effort to entrain the gases, but 
 it is not clear that there is any gain in efficiency to be realized 
 in such a result. It is possible that, as the mixing action is in- 
 creased, the induced action may be diminished, and that the 
 sum total of the effect produced may remain nearly constant. 
 The work which has thus far been done is not conclusive on 
 this point, but the evidence tends to show that the more com- 
 pact and dense the jet the higher its efficiency. It is certainly 
 clear that, for the jets experimented upon, the mixing action is 
 hardly more than incidental to the induced action, the latter 
 constituting the influence through which the work of the jet is 
 chiefly accomplished. 
 
 In connection with the diagrams Figs. 37 to 39, Fig. 42, 
 which is from a photograph of the jet delivered from a double 
 nozzle, will be of interest. The view represents what one sees 
 when looking into a front-end when the locomotive is being 
 run with the front door open. 
 
 30. Distribution of Sparks within the Stack. Designers 
 of draft appliances, being confronted with the problem of inter- 
 
86 
 
 LOCOMOTIVE SPARKS. 
 
 cepting the sparks at some point between the front tube-sheet 
 and the top of the stack, will be helped in this work by a 
 knowledge of the course taken by the sparks. It is thought 
 proper, therefore, to make of record such information upon this 
 point as has been derived from certain investigations, some 
 features of which have already been discussed. For the pur- 
 pose of such a presentation the data as obtained for Test 
 No. 4, Table I, Chapter III, have been selected as fairly repre- 
 sentative of the general conditions. 
 
 Sparks passing through a square-inch section of the stack 
 at various points are indicated in position and value by the 
 
 POUNDS OF SPARKS PASSING OUT OF STACK PER 
 
 SQUARE INCH OF STACK AREA PER KOUR AT THE 
 
 VARIOUS PLACES DESIGNATED- THE TWO FULL 
 
 CIRCLES INDICATE THE SIZE AND LOCATION 
 
 OF THE DOUBLE EXHAUST-TIP. 
 
 FIG. 43- 
 
 numerals given in Fig. 43. It will be seen that the weight 
 diminishes steadily as the positions of observation are changed 
 from the outside to points nearer the centre, and also that 
 those points which are most remote from the action of the 
 exhaust-jet show the largest weight of sparks. Fig. 44 gives 
 the weight of sparks per hour for the several annular rings into 
 
ACTION OF THE EXHAUST-JET. 87 
 
 which the area of the stack is assumed to be divided; the 
 breadth of each ring being 2 inches. Here, again, the fact 
 that the sparks follow the wall of the stack rather than the 
 centre of the stream is disclosed; more than 50 per cent of the 
 
 POUNDS OF SPARKS PASSING OUT OF 
 STACK'PER HOUR IN THE SEVERAL 
 AREAS INDICATED. 
 
 FIG. 44. 
 
 FIG. 45. 
 
 whole weight being credited to an area embraced by a ring 
 2 inches broad measured from the outside circumference of the 
 
88 LOCOMOTIVE SPARKS. 
 
 stream. The distribution of sparks in the stack is shown 
 graphically by Fig. 45. This figure may be accepted as a 
 correct graphical presentation of the comparative density of 
 the sparks throughout all portions of the cross-section of the 
 stack. 
 
 The conclusion concerning distribution is that the sparks 
 follow most readily those portions of the stream issuing from 
 the stack which have the lowest velocity, which conclusion is 
 entirely consistent with the information already presented re- 
 garding the action of the exhaust-jet. It should be noted, 
 however, that these observations were made on a cross-section 
 of the stream at a point immediately after it issued from the 
 stack, and may not represent conditions actually existing in 
 the stack. 
 
CHAPTER VI. 
 
 SPREAD OF SPARKS FROM LOCOMOTIVES AS DISCLOSED 
 BY OBSERVATIONS ALONG THE RIGHT-OF-WAY. 
 
 THE preceding chapters have served to show that all loco- 
 motives when working under normal conditions discharge 
 particles of ash and fuel from the top of their stacks. It has 
 been shown that the fuel-value of the material thus discharged 
 is considerable. We are now to consider what is the distribu- 
 tion of the material discharged over the surface of the ground 
 in the immediate vicinity of the track, and what liability there 
 is of fire arising from its presence. 
 
 31. Experiments and Results. To secure information 
 covering this point, investigations under the direction of the 
 author were first undertaken by Mr. George F. Mug, M.E.,* 
 who made observations both at the Purdue experimental loco- 
 motive and along the right-of-way. While Mr. Mug obtained 
 much valuable data, his efforts were largely given to the 
 developments of methods of procedure. In this he was so 
 successful that subsequent investigations have been based upon 
 his work. The most elaborate data thus far obtained are those 
 of Messrs. Ducas and Dill, from whose thesis t the facts of this 
 chapter are chiefly drawn. 
 
 * " A Study of the Cinder- and Spark-losses in Locomotives," a thesis 
 by George F. Mug, B.S., candidate for the degree of M.E., Purdue 
 University, June, 1896. 
 
 f " Spark-losses from Locomotives on the Road," a thesis by J. B. 
 Dill and Charles Ducas, candidates for the degree of B.S., Purdue Uni- 
 versity, June, 1900. 
 
 8q 
 
9 o 
 
 LOCOMOTIVE SPARKS. 
 
 The method employed may be described as follows : ten 
 metal pans 22 inches square were placed in line at right angles 
 
 FIG. 46. 
 
 to the track from 10 to 100 feet apart, and on the leeward side, 
 all as indicated by Fig. 46. The exact distance of each pan 
 from the centre of the track is shown by Table V, and a view of 
 the field with the pans in position by Fig. 47. The pans were 
 placed on one side or the other of the track, depending upon 
 
FIG. 47. 
 
 TABLE V. 
 
 Number of Test. 
 
 Distances of Pans from Centre of Track in Feet. 
 
 I 2 3 
 
 15 
 
 20 
 2O 
 
 25 
 
 35 
 40 
 
 35 
 50 
 60 
 
 45 
 65 
 80 
 
 70 
 80 
 
 IOO 
 
 IOO 
 IOO 
 
 125 
 
 150 
 125 
 1 60 
 
 2OO 
 
 175 
 
 2OO 
 
 250 
 250 
 250 
 
 350 
 350 
 
 350 
 
 4n 6 7 8 o 
 
 TO II 12 17 IJ.. 
 
 
SPREAD OF SPARKS FROM LOCOMOTIVES. 
 
 93 
 
 whether the wind was from the north or the south. A layer of 
 cotton in the bottom of each pan served to retain sparks which 
 otherwise might have been blown away by the wind, and was 
 expected to indicate by a scorched mark the degree of heat in 
 the spark. The place selected for conducting the tests was at 
 the top of a grade on the Lake Erie & Western Railroad, at a 
 point about two miles west of the Lafayette station. A profile 
 of the road in this vicinity is given as Fig. 48. The section of 
 track involved is used jointly by the L. E. & W. R. R. and by 
 the Big Four Company, all Indianapolis and Chicago trains of 
 
 370. 
 
 360. 
 
 365. 
 FIG. 48. 
 
 the latter company passing over it. It is to be noted that, 
 from the start at the station, locomotives have a heavy pull all 
 the way to the point where the observations were made, with 
 heavy grades still beyond. They were therefore invariably 
 working very hard when passing the point of observation. 
 Observations were made only on those trains which came up 
 the grade. When others passed the pans were covered. 
 
 The observations were such as served to make of record 
 the direction of wind, velocity of wind, temperature of the 
 
94 LOCOMOTIVE SP4RKS. 
 
 atmosphere, character of train (whether freight or passenger), 
 number of cars in train, time required to pass between two 
 stakes set at a known distance apart, type, name and number 
 of locomotive, and character of smoke (light, dark, very dark, 
 or black). From the observed time in passing between the 
 two stakes the speed of the train was calculated. A photo- 
 graph of each train was also taken. After the train had passed, 
 all the sparks caught in each pan were carefully collected, 
 placed in a separate bottle, and properly labelled. 
 
 Table VI presents a summary of the general observations 
 obtained during the progress of the tests. It is to be noted 
 that most of the freight trains were run with a " pusher " in 
 the rear, and the sample sparks collected represent the dis- 
 charge from two engines. The tests include conditions for 
 which the wind velocities varied from a little over five miles 
 per hour to nearly twelve miles per hour. 
 
 The weight of sparks caught in each pan for each test, as 
 well as the weight falling upon an area of 10 X 10 feet for 
 which each pan is the geometrical centre, as calculated from 
 the weight collected in the pan, is given in Tables VII and 
 VIII. All weights are in grammes. From the fourteen 
 different tests which were made, six have been selected as 
 typical, to be made the subject of a more detailed description. 
 The results of these fairly represent the whole series. They 
 are so selected as to include the full range of conditions which 
 were obtained. The collection from each pan for the six tests 
 selected is shown in detail in pages 1 10 to 127. The sketches 
 represent the actual size and shape of all the sparks caught in 
 each pan for the several tests under consideration. Tests 
 Nos. 2 and 10 are those for which the spread of sparks is 
 greatest ; Tests Nos. 5 and 6, those for which it is of average 
 extent; and Tests Nos. 8 and 14, those for which it is least. 
 In Tests Nos. 2 and 10 the greatest weight of sparks is found 
 
SPREAD OF SPARKS FROM LOCOMOTIVES. 
 
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 vo o 
 
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 8 8 8 
 
 
 O >o 
 
 8 5 ^ 
 
 
 10 " 
 
 8Q 1 \C 
 6 ~ 
 
 Test Number. 
 
 Distance of pans from 
 centre of track. Feet. 
 Weight of sparks caught 
 in each pan. Grammes. 
 Equivalent weight of 
 sparks per 100 square 
 feet. Grammes 
 
 Test Number. 
 
 Distance of pans from 
 centre of track. Feet. 
 Weight of sparks caught 
 in each pan. Grammes 
 Equivalent weight of 
 sparks per 100 square 
 feet. Grammes.... . .. 
 
 Test Number. 
 
 Distance of pans from 
 centre of track. Feet 
 Weight of sparks caught 
 in each pan. Grammes 
 Equivalent weight of 
 sparks per 100 square 
 feet. Grammes 
 
 Test Number. 
 
 Distance of pans from 
 centre of track. Feet. 
 Weight of sparks caught 
 in each pan. Grammes 
 Equivalent weight of 
 sparks per 100 square 
 feet. Grammes 
 
SPREAD OF SPARKS FROM LOCOMOTIVES* 
 
 97 
 
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 8 ff ? 
 
 Test Number. 
 
 Distance of pans from 
 centre of tr^.ck. Feet. 
 Weight of sparks caught 
 in each pan. Grammes 
 Equivalent weight of 
 sparks per 100 square 
 feet. Grammes 
 
 Test Number. 
 
 Distance of pans from 
 centre of track. Feet. 
 Weight of sparks caught 
 in each pan. Grammes 
 Equivalent weight of 
 sparks per 100 square 
 feet. Grammes 
 
 Test Number. 
 
 Distance of pans from 
 centre of track. Feet. 
 Weight of sparks caught 
 in each pan. Grammes 
 Equivalent weight of 
 sparks per 100 square 
 feet. Grammes 
 
 !?: 
 
98 LOCOMOTIVE SPARKS. 
 
 at 70 and 80 feet from the track, respectively; in Tests Nos. 
 5 and 6 the greatest weight is found at 50 and 65 feet, re- 
 spectively; and in Tests Nos. 8 and 14 the greatest weight is 
 at 20 and 40 feet, respectively. 
 
 It will be of little value to attempt to compare one test 
 with another, even though the conditions as to wind may be 
 apparently the same. Such a comparison would only lead to 
 flagrant inconsistencies. It will be shown in a subsequent 
 chapter that the distance traversed by a spark after leaving 
 the stack is dependent in part on the initial upward impulse 
 received. This in turn is dependent on conditions within the 
 locomotive itself, and concerning which no information could 
 be made of record. It is, therefore, but reasonable to expect 
 that even under like conditions of wind the distribution of 
 sparks for individual tests may be widely different, and the 
 results show that such a condition actually exists. 
 
 To better show the distribution of sparks, the weight 
 caught in each pan for each of the six typical tests is shown 
 graphically by Figs. 50, 52, 54, 56, 58, and 59. 
 
 In connection with the diagrams, photographs of the head 
 of the several trains involved by the tests are given as Figs. 
 49> 5 J > 53 ' 55' an< ^ 57' eacn of the six tests being represented 
 excepting No. 8, for which the photograph failed. The photo- 
 graphs indicate something of the heavy service which the 
 locomotives were performing, also something of the direction 
 and velocity of the wind.- It would seem that the total weight 
 of sparks discharged by the locomotives shown, under the 
 conditions which have been described, must have been nearly 
 maximum for any locomotive in good condition. With higher 
 wind velocities the sparks might be spread over somewhat 
 greater distances, but it is hardly likely that they would ever 
 be more thickly strewn or that the relation of size to distance 
 from track would be greatly changed. 
 
SPARK-LOSSES FROM LOCOMOTIVES ON THE ROAD. 
 TEST NO. 2. TRAIN WITH "PUSHER." 
 
 FIG. 49. One of the two locomotives during the test, the record for 
 which is given below. 
 
 25 50 75 
 
 100 125 150 175 200 225 350 275 300 
 
 DISTANCES OF PANS FROM TRACK IN FEET. 
 
 FIG. 50. 
 
 325 350 
 
 99 
 
SPARK-LOSSES FROM LOCOMOTIVES ON THE ROAD. 
 TEST NO. 10. TRAIN WITH l< PUSHER." 
 
 FIG. 51. One of the two locomotives during the test, the record for 
 which is given below. 
 
 50 75 100 125 150 175 300 225 350 875 300 385 350 
 
 INSTANCES OF PANS FROM TRACK IN FEET, 
 
 FIG. 52. 
 
 101 
 
SPARK-LOSSES FROM LOCOMOTIVES ON THE ROAD. 
 TEST NO. 5. TRAIN WITH "PUSHER." 
 
 FIG. 53. One of the two locomotives during the test, the record for 
 
 which is given below. 
 
 25 60 
 
 75 100 125 150 175 200 225 250 275 
 
 DISTANCES OF PANS FROM TRACK IN FEET. 
 
 FIG. 54- 
 
 325 350 
 
 103 
 
SPARK-LOSSES FROM LOCOMOTIVES ON THE ROAD. 
 TEST NO. 6. 
 
 F K;> 55 The locomotive during the test, the record for which is given 
 
 below. 
 
 25 50 
 
 75 100 125 150 175 200 225 250 275 300 325 360 
 
 DISTANCES OF PANS FROM TRACK IN FEET. 
 
 FIG. 56. 
 
 105 
 
SPARK-LOSSES FROM LOCOMOTIVES ON THE ROAD. 
 TEST NO. 14. TRAIN WITH "PUSHER." 
 
 FiG. 57. One of the two locomotives during the test, the record 
 which is given below. 
 
 for 
 
 25 50 
 
 75 100 125 150 175 200 225 250 275 300 
 DISTANCES O.F BANS FROM TRACK IN FEET. 
 
 FIG. 58. 
 
 325 350 
 
 107 
 
SPARK-LOSSES FROM LOCOMOTIVES ON THE ROAD. 
 TEST NO. 8. 
 
 The photograph for this test failed. The following is a 
 summary of the conditions which prevailed: 
 
 Number of locomotives I 
 
 Type of locomotive Mogul 
 
 Number of freight-cars 12 
 
 Speed of train, miles per hour 21.6 
 
 Velocity of wind, miles per hour 7 
 
 Character of smoke . . dark 
 
 \ 
 
 75 100 125 150 175 200 225 250 275 
 
 DISTANCES OF PANS FROM TRACK IN FEET. 
 
 FIG. 59- 
 
 300 325 350 
 
 109 
 
110 
 
 LOCOMOTIVE SPARKS. 
 
 SPARKS FROM TEST No. 2. 
 
 THIS test and Test No. 10, the results of which follow, are 
 typical of those tests in which the heaviest fall of sparks is 
 found at the greatest distance from the track. The spots 
 within each rectangle show the number and actual size of 
 sparks collected in each pan. The rectangle does not indicate 
 the size of the pan, which was 22 inches square. 
 
 The sparks collected include those deposited by the 
 locomotive at the head of the train (Fig. 49) and by the 
 4 'pusher " at its rear. 
 
 Speed of train 15.7 miles per hour 
 
 Velocity of wind 1 1.6 miles per hour 
 
 Number of freight-cars 29 
 
 15 
 
 Actual size and number of 
 .sparks falling within an area of 
 484 square inches, at a distance 
 of 75 feet from the centre of the 
 track. 
 
 2 
 
 25 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 25 feet from the centre of the 
 track. 
 
SPREAD OF SPARKS FROM LOCOMOTIVES. ill 
 
 SPARKS FROM TEST No. 2. Continued. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 35 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 45 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of jo feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 100 feet from the centre of the 
 track. 
 
 45 
 
 70 
 
 too 
 
 : ., 
 
 **!> 
 
 <a 9 <* 
 
 i *** ^^k, ^rf * 4 
 
 VMi-^v 
 
 1k> ^^ i, ^ * 
 
 ,*f . 4> Wifl . T a 
 
112 
 
 LOCOMOTIVE SPARKS. 
 
 SPARKS FROM TEST No. 2. Continued. 
 
 150 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 150 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 200 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 250 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches at a distance ~ 
 f 35 f eet from the centre of the 
 track. 
 
 200 
 
 . * 
 
 * y . ' 
 
 250 
 
 350 
 
SPREAD OF SPARKS FROM LOCOMOTIVES. 
 
 SPARKS FROM TEST No. 10. 
 
 THIS test and Test No. 2, the results of which are given 
 on preceding pages, are typical of those tests in which the 
 heaviest fall of sparks is found at the greatest distance from the 
 track. The spots within each rectangle show the number and 
 actual size of sparks collected in each pan. The rectangle does 
 not indicate the size of the pan, which was 22 inches square. 
 
 The sparks collected include those deposited by the 
 locomotive at the head of the train (Fig. 51) and by the 
 ' ' pusher ' ' at its rear. 
 
 Speed of train 14.9 miles per hour 
 
 Velocity of wind 7.9 miles per hour 
 
 Number of freight-cars 34 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 20 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 4.0 feet from the centre of the 
 track. 
 
 10 
 
 40 
 
114 LOCOMOTIVE SPARKS. 
 
 SPARKS FROM TEST No. 10. Continued. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 60 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 80 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 100 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 125 feet from the centre of the 
 track. 
 
 10 
 
 * v 
 
 ', ** 
 
 so 
 
 10 
 
 + 
 
 
 too 
 
 125 
 
SPREAD OF SPARKS FROM LOCOMOTIVES. 
 
 SPARKS FROM TEST No. 10. Continued. 
 
 160 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 160 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 200 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 250 feet from the centre of the 
 track. 
 
 10 
 
 10 
 
 10 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 350 feet from the centre of the 
 track. 
 
 200 
 
 250 
 
 350 
 
n6 
 
 LOCOMOTIVE SPARKS. 
 
 SPARKS FROM TEST No. 5. 
 
 THIS test and Test No. 6, the results of which follow, are 
 typical of those tests in which the heaviest fall of sparks is 
 found at a moderate distance from the track. The spots within 
 each rectangle show the number and actual size of sparks col- 
 lected in each pan. The rectangle does not indicate the size 
 of the pan, which was 22 inches square. 
 
 The sparks collected include those deposited by the 
 locomotive at the head of the train (Fig. 53) and by the 
 ' ' pusher ' ' at the rear. 
 
 Speed of train 15.1 miles per hour 
 
 Velocity of wind 8.7 miles per hour 
 
 Number of freight-cars 34 
 
 20 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 5 
 of 20 feet from the centre of the 
 track. 
 
 . 
 
 35 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance _ 
 of 35 feet from the centre of the 
 track. 
 
SPREAD OF SPARKS FROM LOCOMOTIVES. 
 
 117 
 
 SPARKS FROM TEST No. 5. Continued. 
 
 50 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 
 9 
 
 of 50 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 65 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 5 
 of 80 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 100 feet from the centre of the 
 track. 
 
 65 
 
 80 
 
 100 
 
n8 
 
 LOCOMOTIVE SPARKS. 
 
 SPARKS FROM TEST No. 5. Continued. 
 
 125 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 5 
 of 125 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 5 
 of 775 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance r- 
 of 250 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance ,. 
 f 35 f ee t from the centre of the 
 track. 
 
 175 
 
 250 
 
 350 
 
SPREAD OF SPARKS FROM LOCOMOTIVES. 
 
 119, 
 
 SPARKS FROM TEST No. 6. 
 
 THIS test and Test No. 5, the results of which are given 
 on preceding pages, are typical of those tests in which the 
 heaviest fall of sparks is found at a moderate distance from the 
 track. The spots within each rectangle show the number and 
 actual size of sparks collected in each pan. The rectangle does 
 not indicate the size of the pan, which was 22 inches square. 
 
 The sparks collected are those deposited by a single 
 locomotive (Fig. 55) at the head of a train. 
 
 Speed of train 23.3 miles per hour 
 
 Velocity of wind 9.8 miles per hour 
 
 Number of freight-cars 1 1 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 20 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 35 feet from the centre of the 
 track. 
 
 35 
 
120 
 
 LOCOMOTIVE SPARKS. 
 
 SPARKS FROM TEST No. 6. Continued. 
 
 50 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 50 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 65 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 80 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 100 feet from the centre of the 
 track. 
 
 65 
 
 ' 
 
 100 
 
SPREAD OF SPARKS FROM LOCOMOTIVES. 
 
 121 
 
 SPARKS FROM TEST No. 6. Continued. 
 
 125 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 125 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 775 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 250 feet from the centre of the 
 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 350 feet from the centre of the 
 track. 
 
 115 
 
 250 
 
 r. 
 
 350 
 
122 
 
 LOCOMOTIVE SPARKS. 
 
 SPARKS FROM TEST No. 8. 
 
 THIS test and Test No. 14, the results of which follow, are 
 typical of those tests in which the heaviest fall of sparks is 
 found near to the track. The spots within each rectangle show 
 the number and actual size of sparks collected in each pan. 
 The rectangle does not indicate the size of the pan, which was 
 22 inches square. 
 
 The sparks collected were from a single locomotive at the 
 head of the train. 
 
 Speed of train 21.6 miles per hour 
 
 Velocity of wind 7 miles per hour 
 
 Number of freight-cars 12 
 
 20 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 20 feet from the centre of the 
 track. 
 
 35 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 
 o 
 
 f 35 f eet from the centre of the 
 track. 
 
SPREAD OF SPARKS FROM LOCOMOTIVES. 
 
 123 
 
 SPARKS FROM TEST No. 8. Continued. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 50 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 65 feet from the cencre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 80 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 100 feet from the centre of the 
 track. 
 
 50 
 
 
 65 
 
 '*- ' < ' 
 
 80 
 
 100 
 
 . 
 
I2 4 
 
 LOCOMOTIVE SPARKS. 
 
 SPARKS FROM TEST No. 8. Continued. 
 
 125 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 125 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 775 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance ~ 
 of 250 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 350 feet from the centre of the 
 track. 
 
 175 
 
 250 
 
 350 
 
SPREAD OF SPARKS FROM LOCOMOTIVES. 
 
 125 
 
 SPARKS FROM TEST No. 14. 
 
 THIS test and Test No. 8, the results of which are given 
 on preceding pages, are typical of those tests in which the 
 heaviest fall of sparks is found near to the track. The spots 
 within each rectangle show the number and actual size of 
 sparks collected in each pan. The rectangle does not indicate 
 the size of pan, which was 22 inches square. 
 
 The sparks collected include those deposited by the 
 locomotive at the head of the train (Fig. 57) and by its 
 * ' pusher ' ' at the rear. 
 
 Speed of train 18.3 miles per hour 
 
 Velocity of wind 8.9 miles per hour 
 
 Number of freight-cars 30 
 
 20 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 20 feet from the centre of the 
 track. 
 
 40 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance - 
 of 4.0 feet from the centre of the 
 track. 
 
126 
 
 LOCOMOTIVE SPARKS. 
 
 SPARKS FROM TEST No. 14. Continued. 
 
 60 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 60 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 80 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 100 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance i 
 of 125 feet from the centre of the 
 track. 
 
 80 
 
 100 
 
 
 
 *!**; : -v 
 
 fo?v\ : : 
 *>/:' 
 
 125 
 
SPREAD OF SPARKS FROM LOCOMOTIVES. 
 
 127 
 
 SPARKS FROM TEST No. 14. Continued. 
 
 160 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 1 60 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 200 feet from the centre of the 
 track. 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance 
 of 250 feet from the centre of the 
 track. 
 
 14 
 
 Actual size and number of 
 sparks falling within an area of 
 484 square inches, at a distance .. 
 f 35 f eet from the centre of the 
 track. 
 
 200 
 
 250 
 
 350 
 
128 LOCOMOTIVE SPARKS. 
 
 32. A Summarized Statement of Results of experiments 
 to determine the spread of sparks along the right-of-way is as 
 follows : 
 
 1. The greatest number of sparks fell at from 35 to 150 
 feet from the centre of the track. It may therefore be assumed, 
 from the data at hand, that the possibility of fire is greatest 
 within these limits. 
 
 2. With a few exceptions, the pans nearest the track, i.e., 
 from 15 to 20 feet, caught but few sparks. Local conditions, 
 due to air-currents about the train, may in part be responsible 
 for this. 
 
 3. No scorching of the cotton in the pans was in any case 
 observed. This may be accounted for by the fact that during 
 the time the tests were run (in April and May) the tempera- 
 tures were comparatively low. Some of the larger sparks were 
 quite warm, however, when picked up immediately after falling. 
 
 4. Beyond 125 feet from the centre of the track the sparks 
 were of such character as to preclude any possibility of fire 
 from them. 
 
 5. In March, preceding the tests, when a light crust of 
 snow covered the ground, it was possible to trace evidence of 
 dust from passing locomotives at a distance of 800 feet from 
 the track. The wind velocity was high about 20 miles an 
 hour. Nothing in this observation should be interpreted as in 
 conflict with the statement of the preceding paragraph. 
 
CHAPTER VII. 
 
 THEORETICAL CONSIDERATIONS AFFECTING THE 
 SPREAD OF SPARKS BY MOVING LOCOMOTIVES. 
 
 33. THE results of actual observations upon the size of 
 sparks, and the extent of area over which they are distributed 
 by moving locomotives, have been presented in the preceding" 
 chapter. It is the purpose of the present chapter to discuss 
 the various forces affecting the spread of sparks and to show 
 their relation one to another, so that if certain conditions are 
 assumed to prevail, the resulting effect can be predicted. 
 
 34. Preliminary Conceptions. All change of motion is 
 the result of force. If a body freed from the influence of all 
 forces save that of gravity be thrown vertically upward, the 
 action of gravity will cause it to return by the same path as 
 that by which it rose until it rests upon the same spot from 
 whence it started. Or, if a body in the air is freed from the 
 influence of all forces excepting that of the wind, it will move 
 with the wind in the direction in which the wind is moving and 
 at the same velocity as the wind. The effect of several 
 forces acting at the same time upon a given body was origi- 
 nally stated by Newton as follows: -"When any number 
 of forces act simultaneously upon a body, then whether the 
 body be originally at rest or in motion, each force produces 
 exactly the same effect in magnitude and direction as if acting 
 alone." This principle is often called the Law of Independ- 
 ence of Motion. By this law it will be seen that if a body, as, 
 
 129 
 
13 LOCOMOTIVE SPARKS. 
 
 for example, a spark, be projected upwards in the presence of 
 a strong wind, it will move upward in response to the initial 
 impulse to a certain height and will then descend. This 
 upward and downward movement will extend over the same 
 vertical distances, and will take the same time as would be the 
 case if the wind were not blowing. On the other hand, a 
 spark thus projected will respond to the influence of the wind 
 throughout the time it remains in the air to the same extent 
 that it would if the force of gravitation were not in action. 
 Being, therefore, under the influence of gravity, which tends 
 to retard or to produce motion in vertical lines, and under the 
 influence of the wind, which tends to produce motion in hori- 
 zontal lines, the actual path followed will be a curve. 
 
 35. The Path and Horizontal Displacement of a Body 
 Assumed to be in Air at a given Distance from the Ground 
 and Free to Move Both in Response to Gravity and to the 
 Influence of Wind Acting in a Horizontal Direction. If, 
 now, we assume a body, as A, Fig. 60, held in the air at a 
 given distance from the ground and subject to the action of 
 gravity and to the influence of wind, it will, when released, 
 move in obedience to both of these forces; it will fall through 
 the height // to the ground, and in the time occupied in falling 
 the wind will have caused it to move horizontally through the 
 distance d, the path followed by the body being described by 
 the curve AB. From this general statement it is possible to 
 express mathematically the relation between the height of the 
 fall h and the horizontal displacement d, which is 
 
 /aX 
 
 - V ? ' 
 
 in which d is the horizontal distance traversed in feet; z/ f the 
 velocity of wind in feet per second; //, the height through 
 
SPREAD OF SPARKS BY MO YIN G LOCOMOTIVES. 
 
 which the body is allowed to fall in response to gravity; and 
 j the acceleration due to gravity, or 32.2.* By use of this 
 
 FIG. 60. 
 
 * The full demonstration is as follows : 
 
 Let v = velocity of wind in feet per second; 
 
 h = iiitial height in feet which a freely falling body may be above 
 
 the ground; 
 d = horizontal distance in feet through which the body would 
 
 move in falling to the ground; 
 / = time of descent in seconds; 
 
 g = acceleration due to gravity (= 32.2 feet per second). 
 If the effect of the wind velocity alone is considered, then 
 
 d = vt, (i) 
 
 whence 
 
 t = * (2) 
 
 V 
 
 If the effect of the acceleration of gravity alone is considered, then, 
 from the law of falling bodies, 
 
 h = &/*, ........... (3) 
 
 whence 
 
 t if 
 
 (4) 
 
 But when the forces act simultaneously, the time /, required to fall the 
 distance h, is the same as the time required to travel the distance d. Ex- 
 
1 3 2 
 
 LOCOMOTIVE SPARKS. 
 
 formula the values for d shown by Table IX have been 
 obtained. The table shows how far it is possible for a particle 
 to be borne by the wind starting from points at various dis- 
 tances from the ground and influenced by wind of different 
 velocities. 
 
 TABLE IX. 
 
 SHOWING THE HORIZONTAL DISPLACEMENT OF A BODY 
 UNDER THE INFLUENCE OF WIND OF DIFFERENT VE- 
 LOCITIES, WHILE FALLING FROM DIFFERENT HEIGHTS. 
 
 Velocity of 
 Wind. 
 
 Initial Height in Feet from which the Body is Assumed to Start. 
 
 Feet 
 
 Miles 
 
 
 
 
 
 
 
 
 
 per 
 
 Second. 
 
 Hour. 
 
 15 
 
 20 
 
 25 
 
 30 
 
 40 
 
 50 
 
 75 
 
 100 
 
 2.Q3 
 
 2 
 
 2.8 
 
 3-3 
 
 3-6 
 
 4.0 
 
 4.6 
 
 5-2 
 
 6-3 
 
 7.3 
 
 7-34 
 
 5 
 
 7-o 
 
 8.1 
 
 9-i 
 
 10. 
 
 ii. 5 
 
 13-0 
 
 15-8 
 
 18.3 
 
 11.74 
 
 8 
 
 ii. 3 
 
 13-0 
 
 14-5 
 
 16.0 
 
 18.4 
 
 20.8 
 
 25-3 
 
 29.2 
 
 17.60 
 
 12 
 
 16.9 
 
 19-5 
 
 21.8 
 
 23-9 
 
 27.6 
 
 31-2 
 
 38.0 
 
 43-8 
 
 23-47 
 
 16 
 
 22.5 
 
 26.0 
 
 29.1 
 
 3i-9 
 
 36.8 
 
 41.5 
 
 50.5 
 
 58.4 
 
 29-34 
 
 20 
 
 28.2 
 
 32.6 
 
 36.4 
 
 39-9 
 
 46.1 
 
 51.9 
 
 63-3 
 
 73-o 
 
 44.01 
 
 30 
 
 42.2 
 
 48.8 
 
 54-6 
 
 59-8 
 
 69.1 
 
 77.9 
 
 94-9 
 
 109.6 
 
 58.68 
 
 40 
 
 56-3 
 
 65.1 
 
 72.7 
 
 79-8 
 
 92.1 
 
 103.8 
 
 126.6 
 
 146.1 
 
 73-35 
 
 50 
 
 70.4 
 
 81.4 
 
 90.9 
 
 99-7 
 
 II5-I 
 
 129.8 
 
 158.2 
 
 182.6 
 
 88.02 
 
 60 
 
 84-5 
 
 97-7 
 
 109.1 
 
 II9-7 
 
 138.2 
 
 155.8 
 
 189.9 
 
 219.1 
 
 For example, when the initial height // of the body above the 
 ground is 20 feet and the wind velocity is 12 miles per hour, 
 the horizontal distance d is 19.5 feet. Again, when the 
 initial height is 50 feet and the wind velocity is 40 miles per 
 hour, the distance is 103.8 feet. It is to be noted that the 
 
 pressing this fact mathematically by equating the right-hand .members of 
 (2) and (4), we get 
 
 ' = 4/ 2 - 
 
 v g 
 
 whence 
 
 d = 
 
 (5) 
 
 (6) 
 
SPREAD OF SPARKS BY MO V 'ING LOCOMOTIVES. 
 
 133 
 
 equation and the table derived by its use, presuppose that the 
 body in question is free from the action of all forces except that 
 of gravity and that of the horizontal movement of the wind. 
 Under this assumption the values given are absolute. As a 
 matter of fact, a body in falling in air is retarded somewhat by 
 the resistance of the atmosphere, and would therefore be a 
 trifle longer in its descent than is allowed by the formula, with 
 the result that the horizontal distance would also be greater. 
 In another paragraph an attempt will be made to correct for 
 this influence. For the present the' results as given should be 
 accepted as defining the physical relationship applicable to a 
 freely falling body. 
 
 FIG. 61. 
 
 35. The Path and Horizontal Displacement of a Body 
 Projected Vertically Upward when Free to Respond to the 
 Influence of Gravity and of Wind Acting Horizontally. 
 
 Fig. 6 1 is a graphical representation of the path followed by a 
 freely falling body which when starting from a definite point, 
 as A , is projected vertically upward while subject to the action 
 
134 LOCOMOTIVE SPARKS. 
 
 of the wind under the influence of which it is assumed to move 
 horizontally. The arrow g shows the direction of the force of 
 gravity. The arrow v shows the direction of the constant 
 wind velocity. The curved line A BCD shows the path which 
 the body will follow in its journey to the ground. The maxi- 
 mum height, 7/ 2 , is not reached until some distance, ! l , from the 
 initial position. From this point the body gradually falls to 
 the ground through a horizontal distance / 2 . The total hori- 
 zontal distance* traversed by the body is expressed by 
 
 d i 1 
 
 g 
 
 Table X gives values for d as obtained from formula (b) 
 by the substitution of successive values of //., and 7'. The 
 
 * Let v\ = velocity of wind in feet per second; 
 
 hi = initial height in feet of body above ground; 
 
 h?, = maximum height in feet of body above ground; 
 
 g = acceleration of gravity (= 32.2 feet per second); 
 
 d = horizontal distance in feet through which the body would 
 
 move in falling to the ground. 
 
 The path of the body is divided into two parts: that from A to B, and 
 that from B to D. 
 
 The horizontal distance traversed in passing from A to B is ex- 
 pressed by 
 
 The horizontal distance traversed in passing from B to D is expressed 
 by 
 
 ...... .... (2) 
 
 But the total horizontal distance is /, + / a = d. Therefore 
 
 , i i A9 , f . 
 
 d = v ---- \- v - -- ....... (3) 
 
 o 
 
 or 
 
SPREAD OF SPARKS BY MOVING LOCOMOTIVES. 
 
 initial height // x is taken at 15 feet.* For example, when the 
 maximum height to which the body rises is 20 feet and the 
 wind velocity is 12 miles per hour, the horizontal distance d 
 through which the body will travel in falling to the ground is 
 found to be 29.4 feet. If the maximum height be increased 
 to 50 feet and the wind velocity to 40 miles per hour, the 
 horizontal distance d is found to be 191 .4 ; if the wind velocity 
 be 60 miles, the displacement becomes 247.8 feet. 
 
 TABLE X. 
 
 SHOWING THE HORIZONTAL DISPLACEMENT OF A BODY 
 PROJECTED VERTICALLY UPWARD FROM AN INITIAL 
 HEIGHT OF FIFTEEN FEET AND FREE TO MOVE BOTH 
 IN RESPONSE TO GRAVITY AND TO THE INFLUENCE OF 
 WIND ACTING IN A HORIZONTAL DIRECTION. 
 
 Velocity of 
 Wind. 
 
 Maximum Height in Feet to which Body is Projected. 
 
 Feet 
 
 Miles 
 
 
 
 
 
 
 
 
 
 per 
 
 per 
 
 15 
 
 20 
 
 25 
 
 3 
 
 4 o 
 
 50 
 
 75 
 
 TOO 
 
 Second. 
 
 Hour. 
 
 
 
 
 
 
 
 
 
 2-93 
 
 2 
 
 2-8 
 
 4.9 
 
 5-9 
 
 6.8 
 
 8-3 
 
 9.6 
 
 12.0 
 
 I4.I 
 
 7-34 
 
 5 
 
 7.0 
 
 12.2 
 
 14.8 
 
 17.0 
 
 20.7 
 
 23-9 
 
 30.0 
 
 35-2 
 
 11.74 
 
 8 
 
 "3 
 
 19.6 
 
 23-7 
 
 27-3 
 
 33-o 
 
 38.3 
 
 48.0 
 
 56.2 
 
 17.60 
 
 12 
 
 16.9 
 
 29.4 
 
 35-6 
 
 40.9 
 
 49.6 
 
 57-4 
 
 71-9 
 
 84-4 
 
 23-47 
 
 16 
 
 22-5 
 
 39-2 
 
 47-5 
 
 54-6 
 
 66.1 
 
 76.5 
 
 95-i 
 
 112.5 
 
 29-34 
 
 20 
 
 28.2 
 
 50.0 
 
 59-4 
 
 68.2 
 
 82.6 
 
 95-7 
 
 119.9 
 
 140.6 
 
 44.01 
 
 30 
 
 42.2 
 
 73-5 
 
 89.1 
 
 102.3 
 
 123.9 
 
 143-5 
 
 179.9 
 
 210.9 
 
 58.68 
 
 40 
 
 56.3 
 
 98.0 
 
 118.7 
 
 136.4 
 
 165.2 
 
 I9I-3 
 
 239-8 
 
 281.2 
 
 73-35 
 
 50 
 
 70.4 
 
 122.5 
 
 148.4 
 
 170.5 
 
 206.5 
 
 239.1 
 
 299.8 
 
 351-5 
 
 88.02 
 
 60 
 
 84-5 
 
 147.0 
 
 178.1 
 
 204.6 
 
 247.8 
 
 286.9 
 
 359-7 
 
 421.9 
 
 While the results given in Tables IX and X are not with- 
 out value as a basis from which to predict the probable flight 
 of sparks, it should be remembered that the body in the pre- 
 ceding illustrations is assumed to fall freely, as in a vacuum, 
 and when liberated to at once partake of the velocity of the 
 
 * An initial height of 15 feet represents approximately the distance 
 of the top of a locomotive-stack above the ground. 
 
I3 6 LOCOMOTIVE SPARKS. 
 
 wind. We are now to consider what are the modifications in 
 the assumptions and results which will follow the substitution 
 of a spark for a freely falling body. 
 
 37. The Horizontal Displacement of Sparks which are 
 Assumed to be in Air Free to Respond to the Action of 
 Gravity and to the Influence of Wind Acting Horizontally. 
 The theoretical considerations of the preceding paragraphs 
 relative to the action of any freely falling body is applicable to 
 a spark after leaving the stack of a locomotive. The values 
 given in Tables IX and X do not, however, accurately repre- 
 sent the horizontal distances which a spark may be assumed 
 to travel after leaving the stack, owing to the fact that these 
 values were computed by using 32.2 as the acceleration due 
 to gravity. This value represents the velocity of a body 
 starting from rest and falling in vacuum for one second. A 
 spark is a comparatively light body, and the resistance of the 
 atmosphere impedes its movements; hence, after its emission 
 from a locomotive stack, it will remain in the air for a longer 
 time than a heavier or more dense body. In other words, 
 the apparent value of the acceleration of gravity for a spark is 
 less than 32.2 feet per second. Before tables can be con- 
 structed, similar in form to those representing the movement of 
 a freely falling body (Tables IX and X), it is first necessary 
 to determine the acceleration for a falling spark in air. Such a 
 determination has been made experimentally. To serve in this 
 research, special apparatus was designed, the essential details 
 of which are shown in Fig. 62. It consists of three vertical 
 rods, the two outer ones being placed before a graduated scale 
 showing feet and inches. Upon each of these two outer rods 
 slides a horizontal arm, at the outer end of which is fastened 
 a cylindrical tube, open at both ends. Two movable hori- 
 zontal arms extend from the central rod. At the extremities 
 
SPREAD OF SPARKS BY MOVING LOCOMOTIVES. 
 
 137 
 
 FIG. 62. 
 
I3 8 LOCOMOTIVE SPARKS. 
 
 of each of these arms is fastened a flat piece of metal for 
 covering the bottom of the tubes. In conducting the experi- 
 ments the tube A, Fig. 62, was first placed at some predeter 
 mined height 7i l , and the movable bottom C adjusted to the 
 lower end of the tube. The tube B was then placed at some 
 height less than // x , and its bottom piece likewise adjusted. In 
 the upper tube, A, was next placed a small lead bullet. In the 
 lower tube, B, was placed a spark taken from the front-end of a 
 locomotive. A quick rotation of the central rod served to 
 withdraw the bottoms from both tubes simultaneously and to 
 allow their contents, in one case a bullet, and in the other case 
 a spark or cinder, to fall to the floor. By repeated trials the 
 tube B was finally placed at a height such that the spark and 
 bullet both reached the floor at the same instant. By noting 
 the heights /^ and /i. 2 from which the two bodies dropped, 
 respectively, and from a knowledge of the acceleration 01 
 gravity for the bullet (assumed to be 32.2), the acceleration for 
 the falling spark was determined.* 
 
 * Let //i = height in feet of bullet above the floor; 
 Ji-i height in feet of spark above the floor; 
 / = time in seconds of descent for spark and bullet; 
 g = 32-2; 
 a = acceleration for spark. 
 
 Then, from the law of falling bodies: 
 For the bullet 
 
 /Si = \&* ........... (i) 
 
 whence 
 
 For the spark 
 
 ** = i' 2 > . . ......... (3) 
 
 whence 
 
 But the time of descent, /*, is the same for the bullet as for the spark. 
 
SPREAD OF SPARKS BY MOVING LOCOMOTIVES. 139 
 
 A long series of experiments was thus conducted, and from 
 the results obtained the average value of the acceleration for a 
 falling spark was found to be 22.72. The sparks experimented 
 with were both cold and incandescent, but differences due to 
 changes in the temperature of the spark were too small to be 
 detected. 
 
 Tables XI and XII have been computed under conditions 
 identical with Tables IX and X, respectively, except that the 
 value of a (22.72) was used instead of g (32.2). It is to be 
 noted that the values of d given in Tables XI and XII are 
 uniformly greater than those given in Tables IX and X, 
 respectively, a fact entirely consistent with the conditions 
 imposed. 
 
 38. The Effect of the Direction of the Wind on the Dis- 
 tance from the Track to which Sparks may be Carried. It 
 is obvious that a spark projected from a moving locomotive 
 will, other things being equal, travel a maximum distance from 
 the track when the direction of the wind is at right angles to 
 the direction of the track. The values given in the preceding 
 tables may be taken to represent maximum distances from the 
 track at which sparks \vill alight when the direction of the wind 
 is at right angles to the track. For all other directions of 
 wind relative to track, the distances from the track at which 
 sparks will find lodgment will be less than those given in the 
 tables. The diagram Fig. 63 will serve to make these state- 
 Expressing this mathematically by equating the right-hand members of (2) 
 and (4), 
 
 2/5, 2// 2 
 
 ::_-.. ........ ( 5 ) 
 
 Therefore 
 
 (6) 
 
140 
 
 LOCOMOTIVE SPARKS. 
 
 TABLE XL 
 
 SHOWING THE HORIZONTAL DISPLACEMENT OF A SPARK 
 UNDER THE INFLUENCE OF WIND OF DIFFERENT VE- 
 LOCITIES, WHILE FALLING FROM DIFFERENT HEIGHTS. 
 
 Velocity of 
 
 
 Wind. 
 
 
 Feet 
 
 Miles 
 
 
 
 per 
 Second. 
 
 Hour. 
 
 15 
 
 20 
 
 2-93 
 
 2 
 
 3-3 
 
 3-8 
 
 7-34 
 
 5 
 
 8.2 
 
 9-5 
 
 11.74 
 
 8 
 
 i3-i 
 
 15-2 
 
 17.60 
 
 12 
 
 19.7 
 
 22.7 
 
 23-47 
 
 16 
 
 26.2 
 
 30.3 
 
 29-34 
 
 20 
 
 32.8 
 
 37-9 
 
 44-01 
 
 30 
 
 49-2 
 
 56.8 
 
 58.68 
 
 40 
 
 65.6 
 
 75-8 
 
 73-35 
 
 50 
 
 81.9 
 
 94-7 
 
 88.02 
 
 60 
 
 98.3 
 
 II3-7 
 
 Initial Height of Spark in Feet. 
 
 25 
 
 3 
 
 40 
 
 50 
 
 75 
 
 roo 
 
 4.2 
 
 4.6 
 
 5-4 
 
 6.0 
 
 7-4 
 
 8-5 
 
 10.6 
 
 ii. 6 
 
 13-4 
 
 15- 1 
 
 18.4 
 
 21.3 
 
 16.9 
 
 18.6 
 
 21.4 
 
 24.2 
 
 29.5 
 
 34-o 
 
 25-4 
 
 27-9 
 
 32.2 
 
 36.3 
 
 44-2 
 
 5i.o 
 
 33-9 
 
 37-1 
 
 42.9 
 
 48-3 
 
 58.9 
 
 68.0 
 
 42-3 
 
 46.4 
 
 53-6 
 
 60.4 
 
 73-7 
 
 85.0 
 
 63-5 
 
 69.6 
 
 80.4 
 
 90.6 
 
 110.5 
 
 127-5 
 
 84.7 
 
 92.9 
 
 107.2 
 
 120.9 
 
 147.4 
 
 170.0 
 
 105.8 
 
 116.1 
 
 134.0 
 
 151-1 
 
 184.2 
 
 212.5 
 
 127.7 
 
 139-3 
 
 160.8 
 
 181.3 
 
 221 .O 
 
 255-0 
 
 TABLE XII. 
 
 SHOWING THE HORIZONTAL DISPLACEMENT OF A SPARK 
 PROJECTED VERTICALLY UPWARD FROM AN INITIAL 
 HEIGHT OF FIFTEEN FEET AND FREE TO MOVE BOTH 
 IN RESPONSE TO GRAVITY AND TO THE INFLUENCE OF 
 WIND ACTING IN A HORIZONTAL DIRECTION. 
 
 Velocity of 
 Wind. 
 
 Maximum Height in Feet to which the Spark is Projected. 
 
 Feet 
 
 Miles 
 
 
 
 
 
 
 
 
 
 per 
 
 per 
 
 15 
 
 20 
 
 25 
 
 30 
 
 40 
 
 50 
 
 75 
 
 IOO 
 
 Second. 
 
 Hour. 
 
 
 
 
 
 
 
 
 
 2.93 
 
 2 
 
 3-3 
 
 5-7 
 
 6.9 
 
 7-8 
 
 9.6 
 
 II. I 
 
 13.9 
 
 16.4 
 
 7.34 
 
 5 
 
 8.2 
 
 14-3 
 
 17.3 
 
 19.8 
 
 24.0 
 
 27.8 
 
 34-9 
 
 40.9 
 
 11-74 
 
 8 
 
 13-1 
 
 22.8 
 
 27.6 
 
 31-8 
 
 38.5 
 
 44-5 
 
 55-8 
 
 65.5 
 
 17.60 
 
 12 
 
 19.7 
 
 34-2 
 
 41.5 
 
 47.6 
 
 57-7 
 
 66.8 
 
 83-7 
 
 98.2 
 
 23-47 
 
 16 
 
 26.2 
 
 45-6 
 
 55-3 
 
 63-5 
 
 76.9 
 
 89.1 
 
 in. 7 
 
 130.9 
 
 29.34 
 
 20 
 
 32.8 
 
 57-0 
 
 69.1 
 
 79-4 
 
 96.1 
 
 in. 3 
 
 139.6 
 
 163.7 
 
 44.01 
 
 30 
 
 49.2 
 
 85-5 
 
 103-7 
 
 119.2 
 
 144.2 
 
 167.0 
 
 209.4 
 
 245.5 
 
 58.68 
 
 40 
 
 65.5 
 
 114.0 
 
 138.2 
 
 158-8 
 
 192.3 
 
 222.7 
 
 279.1 
 
 327.4 
 
 73-35 
 
 50 
 
 81.9 
 
 142.5 
 
 172.8 
 
 198.5 
 
 240.4 
 
 278.3 
 
 348.9 
 
 409.2 
 
 88.02 
 
 60 
 
 98.3 
 
 171.1 
 
 207.3 
 
 238.1 
 
 288.4 
 
 334-0 
 
 418.7 
 
 491.0 
 
SPREAD OF SPARKS BY MOVING LOCOMOTIVES. 141 
 
 ments clear. Table XIII gives multipliers by the use of 
 which the values in Tables IX to XII, inclusive, can be made 
 to show the distance from the centre of the track at which a 
 spark will alight under the influence of winds which blow at 
 various angles with the direction of the train's motion.* 
 
 TABLE XIII. 
 
 Angle , Fig. 63, which Direction of Wind 
 makes with Direction of the Train's Motion. 
 
 Multipliers to be Used. 
 
 
 30 
 
 500 
 
 
 45 
 
 .707 
 
 
 60 
 
 .866 
 
 For example, from Table XI it will be found that when the 
 initial height is 20 feet and the wind velocity is 1 2 miles per 
 hour, the maximum distance traversed by the spark will be 
 22.7 feet. This distance assumes the wind to blow at right 
 angles with the track. If the wind is assumed to blow at an 
 angle of 45 with the track, this value of d would become 
 .707 X 22.734 = 16.0. In a similar manner corrections may 
 be applied to all the tables. 
 
 39. Effect of Train's Motion on the Distance from the 
 Centre of the Track at which Sparks Find Lodgment. - 
 The train's motion does not affect the maximum distance from 
 the centre of the track at which the spark will alight except 
 in so far as incidental air-currents may have their influence. 
 The present purpose deals with the well-known physical con- 
 ditions only. The ejected spark has the same forward motion 
 
 * The distance AB(\g. 63) traversed by the spark is the same whatever 
 may be the direction of the wind. The distance CB varies with the angle 
 (p>, or 
 
 CB = (AB) sin (i) 
 
142 
 
 LOCOMOTIVE SPARKS. 
 
 
 CO/ 
 
 f 
 
SPREAD OF SPARKS BY MOVING LOCOMOTIVES. 143 
 
144 LOCOMOTIVE SPARKS. 
 
 at the time it is sent forth from the stack as the locomotive 
 itself, and it retains something of this motion until the initial 
 energy is entirely absorbed by frictional contact with the 
 atmosphere. That such motion does not affect the distance 
 from the centre of the track traversed by the spark will appear 
 from Fig. 64, which shows that if the locomotive were at rest, 
 with the wind blowing across the track, the spark leaving A 
 would follow the path d and land at a point B. If the loco- 
 motive were in motion, the spark starting from A would follow 
 a curved path, landing at C. The distance CB depends upon 
 the velocity of the train, but in either case the distances AB 
 and DC depend upon the velocity of the wind and are equal. 
 
CHAPTER VIII. 
 CHANCES OF FIRE FROM SPARKS. 
 
 40. A Review of Certain Facts already Presented. In 
 
 the preceding chapters there has been disclosed much that is 
 important concerning the chances of fire from locomotive 
 sparks. In a review of this matter it is well, first of all, to 
 note that the production of sparks constitutes one of the neces- 
 sary manifestations attending the action of a modern locomo- 
 tive. It is not possible under any circumstances to entirely 
 suppress them. Other things remaining the same, the amount 
 of solid matter thrown from the stack increases when the 
 intensity of the draft-action is increased, so that when the loco- 
 motive is worked to high power more sparks are thrown than 
 when the power developed is low. Their volume varies, also, 
 with the character of fuel ; for example, anthracite coal gives 
 off but few sparks, and these are composed chiefly of ash, 
 while the light and friable lignite coals, such as must be used 
 on many Western roads, are prolific spark-producers. 
 
 The composition of sparks varies from that of ash such as 
 results from the complete combustion of fuel to that of fuel but 
 slightly charred. Ash-sparks are incapable of carrying fire, 
 but sparks composed of partially burned fuel may appear as 
 small coals of coke which glow in the dark, or as incandescent 
 or even as flaming particles. It is noteworthy that incan- 
 descent or flaming sparks constitute but a small proportion of 
 all the solid matter ejected. It appears, also, that those 
 
 145 
 
146 LOCOMOTIVE SPARKS. 
 
 particles which are composed of combustible material and 
 which are, therefore, capable of carrying fire are, except in 
 rare instances, deprived of fire by violent contact with the 
 mechanism of the front-end against which they are driven, and 
 by gathering moisture from the stream of exhaust-steam which 
 serves to send them out into the atmosphere. In the vernac- 
 ular of the road, they are ' ' killed. ' ' 
 
 The size of sparks, as estimated from appearances about 
 the stack, is often deceptive. Incandescent particles emitted, 
 especially at night, appear large, when in reality they are very 
 small. An investigation of the front-end mechanism, through 
 which all sparks must pass before they can reach the outer air, 
 will generally show that it is impossible for sparks larger than 
 a half-kernel of corn to be emitted. An examination of sparks 
 which perchance collect in quiet corners about railroad stations 
 will supply added evidence tending to confirm this statement; 
 the largest spark that can be found generally being much 
 smaller than a half-kernel of corn. 
 
 The fact has been mentioned that but few of all the sparks 
 delivered carry fire, and many of these are doubtless small in 
 size. The experiments in gathering sparks from passing loco- 
 motives, the results of which are recorded in a preceding 
 chapter, failed to disclose a single instance in which a falling 
 spark sufficed to scorch common, unbleached cotton muslin 
 which was laid in the bottom of the collecting-pans to receive 
 them. These observations were made in the months of April 
 and May. It is the testimony of many experienced railway 
 men that atmospheric conditions have much to do with the 
 fire-carrying properties of sparks; that in winter, when the air 
 and all combustible material upon which sparks may fall are 
 cold, fires from sparks never occur; that it is only in midsum- 
 mer, when the temperature of the atmosphere is high, and 
 
CHANCES OF FIRE FROM SPARKS. 147 
 
 when long-continued dry weather has prepared the grass of 
 the roadside for a fire, and a hot sun has warmed it to a high 
 temperature, that fires from sparks are, under normal condi- 
 tions, possible. So small is the heat-carrying power of a spark 
 from a locomotive in good order that it may be doubted whether 
 such a spark was ever the means of communicating fire to the 
 roof of a building, even when under the influence of a summer 
 sun the roof had become well dried and highly heated, except 
 in cases where it may have fallen on materials more finely 
 divided than shingles. 
 
 The distance traversed by sparks, as shown by observa- 
 tions along the track, establishes the danger-line very close to 
 the track. Both a large percentage of all sparks thrown out 
 and the largest individual specimens were found, in the experi- 
 ments herein recorded, within a distance of 100 feet from the 
 centre of the track. This distance fixes the danger-line. As 
 tending to further confirm this statement, the testimony of 
 those who have had occasion to observe the progress of fires 
 originating from locomotives is to the effect that while objects 
 located at considerable distances from the track sometimes 
 burn, the firing of such objects is not the immediate result of a 
 spark from a locomotive; that the initial fire from the locomotive 
 spark is invariably started upon the right-of-way inside of the 
 fence; that this initial fire, which is invariably in the grass, is 
 communicated to a pile of ties or of refuse materials or to the 
 right-of-way fence, the burning embers of which are wind- 
 borne to more distant objects. The fact, therefore, that a 
 building 60 or So yards from the track may burn should not 
 be accepted as evidence that sparks from a locomotive will 
 carry fire to such distances, though a spark may have been an 
 indirect cause of the fire. In all such cases, however, there 
 will be evidence of the initial fire. 
 
148 LOCOMOTIVE SPARKS. 
 
 Against the statements of the preceding paragraphs may 
 be urged the fact that persons standing at considerable dis- 
 tances from the track sometimes feel upon their face and hands 
 the impact of particles discharged from a passing locomotive, 
 the experience indicating that such particles do travel consider- 
 able distances. A close inspection of the particles which thus 
 impress themselves will, however, show them to be very 
 minute, so small in fact as to be hardly more than finely 
 divided dust, wholly incapable of carrying fire. The hands 
 and face are so very sensitive that the impress of such material 
 gives one the impression of being bombarded by fragments of 
 considerable size, but the slightest examination will suffice to 
 convince him of his mistake. Obviously, the present dis- 
 cussion is not concerned with the distribution of these dust- 
 like sparks. 
 
 Finally, as tending to still further confirm the conclusions 
 already stated, it appears that if, in his efforts to make sparks 
 travel long distances from the track, one abandons all con- 
 sideration of local conditions, and bases an estimate on the 
 physical laws governing the movement of all bodies in air, he 
 will be obliged to assume that sparks rise to a very great 
 height, or that they are influenced by a very strong wind, 
 before his results will carry the sparks very far afield. In 
 other words, it may be readily shown by the application of 
 well-known laws applying to falling bodies that sparks suffi- 
 ciently large to carry fire must, under ordinary conditions of 
 discharge and of wind velocity, strike the ground within com- 
 paratively short distances from the track. A concise statement 
 of the facts in this case is presented elsewhere. 
 
 41. The Influence of Air-currents about a Moving Train. 
 A moving train is surrounded by a zone of air which par- 
 takes more or less completely of the motion of the train itself, 
 
CHANCES OF FIRE FROM SPARKS. 149 
 
 depending upon the thickness of the enveloping film which one 
 chooses to consider, and upon the part of the train to which it 
 is assumed to apply. The head of the moving train entering 
 undisturbed air creates strong lines of pressure which wrap 
 themselves in wave-like form about its initial end and are 
 carried along by it. At the rear of the moving train the 
 atmospheric pressure is less than normal, and the air rushes in 
 from all sides in strong currents to fill the space left by the 
 receding train. The effect of eddies thus formed upon the 
 course of sparks discharged by the locomotive at the head of 
 the train is a subject which probably has not been carefully 
 studied. There is, however, much to sustain the theory that 
 such sparks do not escape the influence of the eddies, that 
 they are caught up by them, held within their influence, and 
 finally drawn into the zone of low pressure at the rear of the 
 train. In so far as this argument applies it serves to show 
 that sparks which would otherwise be carried by the wind at 
 right angles to the track are in reality carried along with the 
 strong currents of air which move with the train until they 
 settle upon the track at its rear. 
 
 An observer at the rear of a rapidly moving train cannot 
 "but be impressed by the vigor of the air-currents which are 
 drawn in upon the track in its rear, reaching out to and influ- 
 encing the motion of objects far distant from the track itself. 
 The smoke from a locomotive at the head of a rapidly moving 
 train trails close on the top of the train and drops as it passes 
 over the last car, regardless of the direction or velocity of the 
 wind. 
 
 Professor Francis E. Nipher, who has conducted elaborate 
 experiments in determining the velocity of air-currents imme- 
 diately about a moving train, argues that the effect of a moving 
 train upon the atmosphere is such as to draw objects in its 
 
150 LOCOMOTIVE SPARKS. 
 
 vicinity to itself. Hats which are blown from the heads of 
 persons standing on a station platform are drawn under the 
 train. Bed-mattresses rolled into bundles and piled upon the 
 platform of a freight station have been observed to topple over 
 under the influence of the wind from a passing train, and to 
 be drawn under the wheels.* These considerations imply that 
 sparks are not always free to respond to the influences of the 
 wind, but that they are constrained in their motion, and that 
 the effect of the resistance is to hold them to the course of the 
 train. 
 
 42. Sparks from a Locomotive and Sparks from a Fixed 
 Fire are not Subjected to the Same Influences. It is a matter 
 of common knowledge that sparks and sometimes brands 
 arising from a fixed fire are carried by the wind over long dis- 
 tances. Fragments arising from a burning building, for 
 example, are not infrequently carried a half mile or more. 
 The question at once suggests itself as to why it is that brands 
 from a burning building will travel such distances, while sparks 
 from a locomotive are borne but a few feet. The answer is 
 to be found in the different conditions which prevail in the two 
 cases. Thus the shape of many of the fragments arising from 
 a burning building well fits them for sailing in the air. When 
 such a fragment, as, for example, a shingle, is blazing, it 
 carries with it its own sustaining power. The heat from the 
 flame stimulates ascending currents of air which, acting upon 
 the broad surface of the fragment, tend to keep it in air while 
 the wind bears it away. Again, a fixed fire serves to establish 
 strong and far-reaching air-currents. If the wind is light, the 
 
 * Professor Nipher's discussion and mathematical deductions concern- 
 ing " The Frictional Effect of Railway Trains upon the Air " will be found 
 in the Transactions of the Academy of Science of St. Louis, vol. x, No. 10, 
 issued Nov. 12, 1900. 
 
CHANCES OF FIRE FROM SPARKS. 151 
 
 column of heated air rises as the fire proceeds to greater and 
 greater heights, the activity of the upward current becomes 
 intensely strong, and particles which are caught within its 
 influence are borne to very great heights. When these are of 
 the sort which have been described, they settle very slowly 
 after being released from the influence of the upward current, 
 and drift away with the wind. If a large fixed fire occurs in 
 the presence of a strong wind, the heated current constitutes a 
 vast lane moving obliquely upward, reaching out over territory 
 miles distant from the source of heat, bearing fragments and 
 burning brands. In either case the power of the fixed fire in 
 spreading sparks and brands lies in the fact that the heat 
 developed in any one moment is supplemented by that which 
 is developed the next moment. The currents of air which are 
 set in motion by the heat developed during any one period 
 are accelerated by the heat of a later period. The whole 
 process is cumulative, and, other things being the same, the 
 larger the fire the more rapid the currents become and the 
 farther they extend their influence. 
 
 In striking contrast with all this are the conditions which 
 surround the discharge from the stack of a locomotive. The 
 sparks delivered are comparatively heavy in proportion to the 
 extent of their exposed surface, and are thus not easily borne 
 by ascending air-currents. They are so small that, while they 
 give up the heat they carry very rapidly, the amount liberated 
 is insufficient to stimulate to any marked degree upward cur- 
 rents of air about them. Again, the total amount of heat 
 liberated from a locomotive is small compared with that 
 generated by a burning building and, hence, all effects are less 
 pronounced. As sparks go out of the locomotive stack, they 
 find no far-reaching current to carry them on, for each exhaust 
 from the stack is into undisturbed air. There is absolutely no 
 
152 LOCOMOTIVE SPARKS. 
 
 cumulative effect. The heat-energy delivered is dissipated in 
 the atmosphere which canopies the whole length of track, the 
 discharge of a single minute being perhaps distributed over a 
 mile of territory. There is, therefore, nothing to buoy up 
 the locomotive spark but the initial velocity with which it is 
 projected. From these considerations it should be evident 
 that conclusions based on observations in connection with 
 fixed fires are not applicable to the conditions affecting sparks 
 in locomotive service. 
 
APPENDIX. 
 
 THE PURDUE UNIVERSITY LOCOMOTIVE 
 TESTING-PLANT. 
 
 43. Development of the Plant. The discussions of the 
 preceding chapters so frequently refer to results which have 
 been obtained in connection with the experimental locomotive 
 of Purdue University that it appears desirable that there be 
 added some description of this locomotive and of the mechan- 
 ism upon which it runs. 
 
 The purpose of the experimental testing-plant is to permit 
 the action of a locomotive to be studied with the same ease 
 and degree of accuracy as attends the study of a stationary 
 engine. This is accomplished by converting, in effect, the 
 locomotive into a stationary engine, but by doing this in such a 
 manner that the locomotive remains free to exercise all its 
 usual functions. The experimental locomotive is a machine 
 which in size and in the completeness of its appointments is 
 capable of doing immediate service on the road at the head of 
 a train. 
 
 The plan of mounting a locomotive for experimental pur- 
 poses as developed at Purdue involves (i) supporting wheels 
 carried by shafts running in fixed bearings, to receive the loco- 
 motive drivers and to turn with them; (2) brakes mounted on 
 
 153 
 
154 APPENDIX. 
 
 the shafts of the supporting wheels, which should have suffi- 
 cient capacity to absorb continuously the maximum power of 
 the locomotive; (3) a traction dynamometer to measure the 
 horizontal moving force of the engine on the supporting 
 wheels. 
 
 Assume an engine, thus mounted, to be running in forward 
 motion, the supporting wheels, the faces of which constitute 
 the track, revolving freely in rolling contact with the drivers. 
 The locomotive as a whole being at rest, the track under it 
 (the tops of the supporting wheels) is forced to move back- 
 ward. If now the supporting wheels be retarded in their 
 motion, as, for example, by the action of friction-brakes, the 
 engine must, as a result, tend to move off them. If they be 
 stopped, the drivers must stop or slip. Whether the resistance 
 be great or small, the force which is transmitted from the 
 driver to the supporting wheel to overcome the resistance will, 
 reappear as a stress in the draw-bar, which alone holds the 
 locomotive to its place upon the supporting wheels. The 
 dynamometer constitutes the fixed point with which the draw- 
 bar connects and serves to measure stresses transmitted. 
 
 It is evident from these considerations that the tractive 
 power of such a locomotive may be increased or diminished by 
 simply varying the resistance against which the supporting 
 wheels turn, and that the readings of the traction dynamom- 
 eter will always serve as a basis for calculating work done at 
 the draw-bar. A locomotive thus mounted can be run either 
 ahead or aback under any desired load and at any speed ; and, 
 while thus run, its performance can be determined with a 
 degree of accuracy and completeness far excelling that which 
 it is possible to secure under ordinary conditions on the road. 
 
 The matter of having a locomotive mounted upon the plan 
 described was discussed at Purdue early in the year 1890, and 
 
APPENDIX. 155 
 
 it was so well received that in May, 1891, an order was given 
 the Schenectady Locomotive Works for a 17" X 24" eight- 
 wheeled engine. The details of the mounting were worked 
 out during the two months following. In September the loco- 
 motive had been delivered, and it was in operation before the 
 close of the year. 
 
 This plant, the first of its kind, is described in detail in a 
 paper entitled " An Experimental Locomotive," which was 
 read before the American Society of Mechanical Engineers at 
 the San Francisco meeting in May, 1892. 
 
 On the 23d of January, 1894, the plant was destroyed by 
 fire. Plans for reconstruction were at once entered upon and 
 vigorously pushed. The damaged engine was extricated from 
 the ruins of the building and repaired. The mounting ma- 
 chinery was redesigned, improved in details, and a separate 
 building was built for its accommodation. It is this recon- 
 structed plant (Figs. 65 to 69) which has served in all work 
 the results of which are referred to in preceding chapters. 
 Recently the original locomotive, now known as Schenectady 
 No. I, has given way to one of heavier and more modern 
 design, but the later machine (Schenectady No. 2) is not asso- 
 ciated with any of the results which are herein described. 
 
 A detailed description of the present plant is next pre- 
 sented : 
 
 44. The Wheel-foundation. By reference to Figs. 65 and 
 66 it will be seen that there is provided a wheel-foundation, A, 
 of nearly 25 feet in length. This is more than sufficient to 
 include the driving-wheel base of any standard eight-, ten-, or 
 twelve-wheeled engine. For engines having six wheels 
 coupled, a third supporting axle will be added to those shown, 
 and for engines having eight wheels coupled four new axles, 
 having wheels of smaller diameter than those shown, will be 
 used. 
 
156 
 
 APPENDIX. 
 
APPENDIX. 
 
 '57 
 
 COAL SUPPLr 
 
I5 8 APPENDIX. 
 
 The wheel-foundation carries cast-iron bed-plates, to which 
 are secured pedestals for the support of the axle-boxes. The 
 lower flanges of the pedestals are slotted and the bed-plates 
 have threaded holes spaced along their length. By these 
 means the pedestals may be adjusted to any position along the 
 length of the foundation. 
 
 The boxes in use at present are plain babbitted shaft-bear- 
 ings, and between each bearing and its pedestal a wooden 
 cushion is inserted. A bearing has been designed for use in 
 some special experiments which provides for the suspension of 
 the axle from springs, but this bearing has not yet been used. 
 
 The outer edges of the wheel-foundation are topped by 
 timbers to which the brake-cases are anchored. The brakes 
 which absorb the power of the engine are the ones which were 
 used in the original plant. They are constructed upon a prin- 
 ciple developed by Professor Geo. I. Alden, and their capacity 
 and wearing qualities are beyond question. The load upon 
 them is controlled by varying the pressure of water which 
 circulates through them and carries away the heat. The water- 
 pressure acts upon stationary copper plates which are forced 
 against a moving cast-iron disc, thereby producing friction. 
 No provision is made for determining the load upon each 
 brake, but the loads may be equalized by equalizing the flow 
 and pressure of the cooling water. The sum of these loads 
 plus the friction of the axles in their boxes makes up the sum- 
 total of work to be done ; this work must be given out from 
 the locomotive drivers. It all reappears in the form of draw- 
 bar stress, and its value is shown by the traction dynamometer. 
 An elaborate system of piping (not shown in figures) provides 
 for the circulation of the cooling water for the brakes at what- 
 ever point along the length of the foundation they may be 
 located. 
 
APPENDIX. 159 
 
 45. The Traction Dynamometer. The vibrating character 
 of the stresses to be measured makes the design of the traction 
 dynamometer a matter of some difficulty. The dynamometer 
 of the original plant consisted of an inexpensive system of 
 levers attached to a heavy framework of wood, the vibrations 
 being controlled by dashpots. In the present construction 
 wood as a support is entirely abandoned and a massive brick 
 pier, well stayed with iron rods, has been substituted. The 
 dynamometer itself (B, Figs. 65 and 66) consists of the 
 weighing-head of an Emery testing-machine, the hydraulic 
 support of which is capable not only of transmitting the stress 
 it receives, but also of withstanding the rapid vibrations which 
 the draw-bar transmits to it. The apparatus is of 30,000 
 pounds capacity. 
 
 In view of the enormous force which a locomotive is 
 capable of exerting it would appear, at first sight, that an error 
 of 50 or even 100 pounds in the determination of draw-bar 
 stresses would be of slight consequence, and that great accu- 
 racy in this matter is not required. Under some conditions 
 this conclusion is correct, but under others it is far from true. 
 The work done at the draw-bar is the product of the force 
 exerted multiplied by the space passed over; if the force ex- 
 erted be great and the speed low, a small error in the draw- 
 bar stress is not a matter of great importance ; but if the reverse 
 conditions exist if the speed be high and the draw-bar stress 
 low then it is absolutely necessary that the draw-bar stress 
 be determined with great accuracy. Moreover, high speeds 
 necessarily involve low draw-bar stresses. A locomotive 
 which at 10 miles an hour may pull 12,000 pounds will have 
 difficulty, when running 60 miles per hour, in maintaining a 
 pull of 2500 pounds. These conditions have prompted the 
 Purdue authorities to make extraordinary efforts to secure 
 
160 APPENDIX. 
 
 accurate measurements at the draw-bar, and . they serve as a 
 sufficient justification of the heavy expenditure involved in the 
 purchase of the Emery machine. 
 
 As is well known, the arrangement of the hydraulic support 
 of the Emery testing-machine permits the weighing-scale to 
 be at any convenient distance from the point where the stresses 
 are received. Figs. 65 and 66 show only the receiving end 
 of the apparatus. The draw-bar connects with this apparatus 
 by a ball-joint, which leaves its outer end free to respond to 
 the movement of the locomotive on its springs. A threaded 
 sleeve allows the draw-bar to be lengthened or shortened for 
 a final adjustment of the locomotive to its position upon the 
 supporting wheels; and finally, to meet the proportions of 
 different locomotives, provision is made for a vertical adjust- 
 ment of the entire head of the machine upon its frame. 
 
 46. The Superstructure. Figs. 67 and 68 show the ar- 
 rangement of floors. The " visitors' floor " (Fig. 68) and the 
 fixed floors adjoining are at the level of the rail. The open space 
 over the wheel-foundation is of such dimensions as will easily 
 accommodate an engine having a long driving-wheel base, 
 movable or temporary floors being used to fill in about each 
 different engine, as may be found convenient. The temporary 
 flooring shown is that employed for the locomotive Schenec- 
 tady No. I. 
 
 The level of the * ' tender-floor "is at a sufficient height 
 above the rail to serve as a platform from which to fire. At 
 the rear is a runway leading to the coal-room, the floor of 
 which is somewhat lower than the tender floor. A platform 
 scale is set flush with the floor at the head of the runway. 
 During tests the scale is used for weighing the coal which is 
 delivered to the fireman. 
 
 The feed-water tank, from which the injectors draw their 
 
APPENDIX. 
 
 161 
 
i6 2 
 
 APPENDIX. 
 
APPENDIX. 163 
 
 supply, is shown in the lower right-hand corner of Fig. 68. 
 Above this supply-tank are two small calibrated tanks so 
 arranged that one may be filled while the other is discharging. 
 
 The steam-pump shown on the visitors' floor is for the 
 purpose of supplying water under pressure to the friction-brakes 
 which load the engine. 
 
 The conditions under which the engine is operated are at 
 all times within the control of a single person, whose place is 
 just at the right of the steps leading to the tender-floor. From 
 this position he can see the throttle and reverse-lever and 
 observe all that goes on in the cab. At his right is the 
 dynamometer scale-case, wherein is shown the load at the 
 draw-bar; in front are the gages giving the water-pressure 
 on the brakes ; and under his hand are the valves controlling 
 the circulation of water through the brakes. 
 
 No attempt has been made in these drawings to show small 
 accessory apparatus, neither does it seem necessary to give an 
 enumeration of such details. 
 
 47. The Building. Fig. 69 presents several views of the 
 locomotive building. The entrance-door, which opens upon 
 the visitors' floor, is shown in the south elevation. It is 
 approached from the general laboratory, 45 feet away. 
 
 The north and west elevations show the roof-construction, 
 whereby the upper end of the locomotive stack is made to 
 stand outside of the building. The roof-sections shown may 
 be entirely removed and a door in the cross-wall, which 
 extends between the removable roof and the main roof, pro- 
 vides ample height for the admission of the locomotive to the 
 building. A window in this door (Fig. 68) serves .to give the 
 fireman a clear view of the top of the locomotive stack from 
 his place in the cab, a condition which is essential to good 
 work in firing. Above the stack is a pipe to convey the smoke 
 
i6 4 
 
 APPENDIX. 
 
APPENDIX. 165 
 
 clear of the building. To meet a change in the location of the 
 stack this pipe may be moved to any position along the length 
 of the removable roof. 
 
 The plan of the building (Fig. 69) shows the arrangement 
 of tracks for the locomotive and of those used for supplying 
 coal. 
 
INDEX. 
 
 PAGR 
 
 Acceleration of sparks, experiments to determine 136-138 
 
 Air-currents about a train 148-150 
 
 Alden friction-brake 158 
 
 Analysis of sparks, chemical , . . , 33 
 
 Anthracite coal for locomotives 12, 13 
 
 Arch, function of brick 38 
 
 Area of grate, limitations upon 11-14 
 
 Ash sparks 145 
 
 Atlantic type of locomotives 12 
 
 Authorities on the front-end 7 2 ~73 
 
 Baffle-plate: see Diaphragm. 
 
 Baltimore and Ohio R. R., front-end used on 69 
 
 Basket-netting , 45 
 
 Bell, J. Snowden, front-end arrangements by 52-72 
 
 Bell front-end 69-72 
 
 Blast-pipe: see Exhaust-pipe. 
 
 Boiler, Wootten 12, 13 
 
 Bonnet 50 
 
 Borries, Herr von, experiments on exhaust-jet by 72 
 
 Brakes, Alden fricti;>n 158 
 
 Brick arch 38 
 
 Camden & Atlantic R. R., front-end used on 69 
 
 Chances of fire from sparks 145-152 
 
 Chemical analysis of sparks 33 
 
 Chicago, Burlington and Quincy R. R., front-end used on 61 
 
 Cinder-pot 40, 53, 
 
 Cinder-pocket: see Cinder -pot. 
 
 167 
 
1 68 INDEX. 
 
 PAGB 
 
 Cinders and sparks, definition of 17-18 
 
 " " " production of 18 
 
 " " ' experiments to determine extent of loss by 27-32 
 
 " " " size of 21-25 
 
 ' " " conclusions on 35~3 
 
 (See also Sparks.) 
 
 Coal equivalent of sparks 3 2 ~35 
 
 Coal tests of locomotives 31 
 
 Coburn front-end 69 
 
 Combustion, rates of 9-10 
 
 ' ' conditions governing rates of 10-14 
 
 ' ' effect of draft upon 14 
 
 ' ' experiments on rates of. ... 14 
 
 Comparison of locomotive and stationary plants 6 
 
 Cone : see Diamond-stack. 
 
 Deflector-plate : see Diaphragm. 
 
 Diamond-stack 50 
 
 Diaphragm, function of 41 
 
 ' ' arrangements of 41-43 
 
 Dill. Mr. J. B., experiments by 89 
 
 Direction of wind, effect upon spread of sparks of 139-141 
 
 Distances traversed by sparks 95-143 
 
 Distribution of sparks along right-of-way 95-128 
 
 " within stack 85-88 
 
 Door, fire 7 
 
 Draft, definition of 14 
 
 1 ' factors producing 14 
 
 " effect of 14-15 
 
 " measurement of H-I5 
 
 ' ' comparison of 15 
 
 " appliances 37~73 
 
 " pipes : see Petticoat-pipes. 
 
 Ducas, Mr. Chas., experiments by 89 
 
 Dynamometer, traction 159 
 
 Exhaust-jet, experiments with 74-^5 
 
 " " appearance of - . 84 
 
 " " character of 79-^5 
 
 " ' ' velocity of 78, 82, 85 
 
 Exhaust-nozzle : see Exhaust-pipe. 
 
 Exhaust-pipe, function of 47 
 
 4 ' " forms of 46-48 
 
 Exhaust-tip, function of 49 
 
 " " forms of 49-50 
 
INDEX. 169 
 
 PAGE 
 
 Experiments on rates of combustion 7 rr: T4~ 
 
 " ' ' draft and combustion 15 
 
 " to determine spark- and cinder-losses 2 7~3 2 
 
 " " " spread of sparks 85-128 
 
 11 " " fuel- value of sparks 33 
 
 " " " acceleration of falling sparks 136-138 
 
 Extended front-end : see Front-end. 
 
 Falling bodies, action of 129-144 
 
 Fire-box : see Furnace. 
 
 Fire-door : definition of J 
 
 Fire-grate, definition of ^ 
 
 " " size of 12 
 
 Fire from sparks, chances of 145-152 
 
 Fixed-fire, sparks from a 150-152 
 
 Front-end, a typical 38-41 
 
 " arrangements S3~7 2 
 
 " recommended by Master Mechanics' Association 53, 58, 61, 65 
 
 " used on the C., B. & Q. R. R 61 
 
 " " " " C. I. & L. R. R.: see Coburn Front-end. 
 
 " " " " Camden and Atlantic R. R 69 
 
 " ' " Mexican Central R. R 53-65 
 
 <' " 4< Norfolk and Western R. R 58 
 
 <l " <; Pennsylvania R. R 65 
 
 " " " Pittsburgh, Bessemer and Lake Erie R. R 69-72 
 
 " tt it it Union Pacific R. R 53 
 
 " the Bell 69-72 
 
 u the Coburn 69 
 
 < ' authorities on 7 2 ~73 
 
 Front-ends, kinds of 5-5 2 
 
 Front-sheet: see Tube-sheet. 
 
 Fuel-loss by cinders and sparks 27-32 
 
 Fuel-value of sparks 32-35 
 
 Furnace, locomotive 7 
 
 Furnace-action in locomotive 7 
 
 Garstang, Mr. Wm., tests by 31 
 
 Grate, fire 7 
 
 Grate-area, limitations upon size of. 11-14 
 
 Heating value of sparks 32-35 
 
 Herr, Mr. Edwin M., experiments by 72 
 
 Independence of motion, law of. 129 
 
1 7 INDEX. 
 
 PAGB 
 
 Jet, exhaust 74-85 
 
 " appearance of. < 84 
 
 " character of 79-85 
 
 " velocity of 78, 82, 85 
 
 Limitations affecting design of stationary power-plants 1-3 
 
 " " ii tt moving power-plants 2, 3, 4 
 
 Locomotive testing plant 153-165 
 
 Loss of fuel by cinders and sparks 2 7~32 
 
 Master Mechanics' Association, front-end recommended by 53, 58, 61, 65 
 
 " " " experiments upon exhaust-jet by 79-85 
 
 Mexican Central R. R., front-end used on 53, 61, 65 
 
 Motion, law of independence of 129 
 
 Motion of train, effect upon spread of sparks of 141-144 
 
 Moving power-plants, limitations affecting design of 2, 3, 4 
 
 " " comparison of stationary plants with. . 6 
 
 Mug, Mr. George F., experiments by 89 
 
 Netting, function of 43 
 
 " arrangements of 43~45 
 
 " basket 45 
 
 Newton's law of motion 129 
 
 Nipher, Prof. Francis E., experiments by 149-150 
 
 Norfolk and Western R. R., front-end used on 58 
 
 Nozzle, exhaust: see Exhaust-pipe. 
 
 Open stack 50 
 
 Pennsylvania R. R. , front-end used on. 65 
 
 Petticoat-pipe 45 
 
 Pipe, exhaust 46-48 
 
 Pittsburgh, Bessemer and Lake Erie R. R., front-end used on 69, 72 
 
 Plate, deflector: see Diaphragm. 
 Pocket, cinder: see Cinder-pot. 
 
 Pot, cinder 40, 53 
 
 Prevention of sparks, difficulties besetting 37, 38 
 
 " " " devices employed for the 38-45 
 
 Quereau, Mr. C. H. , report by 42-43 
 
 Quayle, Mr. Robert, experiments by 72 
 
 Rates of combustion 9-10 
 
 Rates of combustion, conditions governing 10-14 
 
 " " " experiments on 14 
 
 Right-of-way, distribution of sparks along 95-128 
 
INDEX. I7 1 
 
 PAGE 
 
 Sauvage Mr. E. , report by 50 
 
 Sheet, front: see Tube- sheet. 
 
 Sheet, tube 7 
 
 Short front-end: see Front-end. 
 
 Size of cinders and sparks 21, 25, 111-128 
 
 Smoke-box: see Front-end. 
 
 Smoke-stack, functions of 50 
 
 " kinds of 53~7-2 
 
 Spark-prevention, difficulties besetting 37~3^ 
 
 1 ' devices employed for 38-45 
 
 Sparks, definition of 18 
 
 11 production of 16, 18 
 
 " ash 145 
 
 " heating value of 3 2 ~35 
 
 " chemical analysis of 33 
 
 Spark-losses, methods of determining 19-21 
 
 ' ' experiments to determine 2 7~3 2 
 
 Spark- and cinder-losses, conclusions concerning 3 5-36 
 
 Sparks, distribution within stack of 85-88 
 
 " method of determining spread of 90-92 
 
 " spread of 89-128 
 
 " summary of tests to determine spread of 97-9$ 
 
 < ' at various distances from track 1 1 1-128 
 
 " theory of spread of. 129-144 
 
 " acceleration of gravity for falling 136-139 
 
 tl effect of direction of wind upon distribution of 139-141 
 
 " " " motion of train upon distribution of 141-144 
 
 " chances of fire from 145-152 
 
 " from fixed fire 150-152 
 
 Stack: see Smoke-stack. 
 
 Stack, diamond 50 
 
 ' ' open 50 
 
 Standard front-end 53, 58, 61, 65 
 
 Stationary power-plants, limitations affecting design of 1-3 
 
 " " comparison of moving power-plants with 6 
 
 " " rates of combustion employed in 9 
 
 " " draft in 15 
 
 Test, Chas. D. , chemical analyses by 33 
 
 Tests of coal 31 
 
 Testing plant, locomotive 153-165 
 
 Theory of spread of sparks 129-144 
 
 Tip, exhaust 49, 50 
 
 Train, air-currents about 148-150 
 
172 INDEX. 
 
 PAtiE 
 
 Traction dynamometer *59. l6 
 
 Trajectories of falling bodies I 3 I ~ I 33 
 
 Troske. Inspector, experiments by 7 2 
 
 Tubes 7 
 
 Tube-sheet 7 
 
 Union Pacific R. R., front-end used on 53 
 
 Velocity of exhaust-jet 7 8 > 82 > 8 5 
 
 Wheel foundation of testing-plant ISS^S 8 
 
 Wootten boiler I2 > X 3 
 
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UNIVERSITY OF CALIFORNIA LIBRARY 
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