Chapter 5

Mr. J. Campbell remarked that at present the great American liners had only the ordinary compound engines, and he thought that, instead of converting them to triple expansion, they should take a step further at once, and adopt quadruple expansion engines. This class of engines was being very successfully built in various parts of the country. He should recommend the adoption of a three-crank six-cylinder engine.

Mr. Hamilton did not think it had been demonstrated that greater efficiency had been got out of twin screws than out of single screws; but there was no doubt they would tend to additional safety.

Mr. Martell said that when they had got satisfactory data, twin screws would be adopted for ships requiring great speed; but they had not got that data at present.

Admiral Sir John Hay, referring to twin screws as applying to sea-going steamers which might be employed for imperial defense, said it was quite certain that the defense of their extended commerce would always require to be assisted by ships such as the Oregon and other magnificent vessels which had been used for that purpose on a recent occasion. He believed that for war purposes the twin screw was recognized by all naval men as having very many advantages. If that were so, it was quite evident that it would be a great advantage, under such conditions as occurred at the loss of the Oregon, if the compartments could be made completely water-tight; and the twin screw, with the separation of the ship longitudinally, gave them the very greatest possible protection. They could not trust to bulkheads that were only closed occasionally by doors. What was required for war purposes was the entire and complete isolation of different parts of the ship, having always practically closed communications between them.

Mr. John then replied on the general discussion. He was pleased to find that they had faith in the future of the twin screw and of subdivision. The public had a right to demand greater safety than they at present had on the Atlantic, or could have with a single screw.

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EXAMINATION QUESTIONS IN GENERAL CONSTRUCTION.

The following is a copy of the last examination paper given to candidates who are desirous of employment in the constructive departments of the municipality of New York:

N.B.--In case candidate does not remember formula or method of solving any problem submitted to him, let him name any work upon the subject where such formula or method may be found.

1. What is civil engineering?

2. Have you ever pursued a course of study in any educational institution, or with any civil engineer, which would fit you for the position of assistant engineer? If so, state when and with whom; state also, in detail, what experience you have had.

3. Have you ever had responsible charge of any public work? If so, state particulars.

4. Solve the following according to the algebraic signs:

/ (6-2/7 - 4-3/9) × 8-7/16 / ------------------------ × 67873.367, and show your work. \/ 4-4/12

5. The population of a certain town in 1880 was 7,095; it having increased 25 per cent. in ten years, what was it in 1870? Show your work.

6. How many feet, board measure, in the flooring of a room 20 feet by 30 feet and 2½ inches thick?

7. Find value of x and y in the following equations:

2 x + 3 y = 33 4 x - y = 17.

8. Find value of x in equation x² - x - 40 = 170.

9. Find value of x in equation

a / a² - x² x - + / ------- = - b \/ x² b

10. Explain the meaning of the expression a½ × b¾.

11. What is a logarithm?

12. What is the base of the common system?

13. In making what calculations are logarithms useful?

14. How do you find the logarithm of a number in a table of logarithms?

15. What are similar triangles?

16. How are similar triangles proportioned to each other?

17. The sides of a polygon being prolonged, what is the sum of all the exterior angles equal to?

18. How do you pass the circumference of a circle through three given points not in the same straight line?

19. How do you describe a square in a circle?

20. In the triangle, b being a right angle, what proportion does d b bear to a d and d c?

21. How do you inscribe a regular hexagon in a circle?

22. What proportion do circumference and areas of circles bear to their radii?

23. How do you find the area of a regular polygon?

24. Of an irregular polygon?

25. Of a circle?

26. How do you find the solid contents of a cylinder?

27. Of a wedge?

28. Of a pyramid?

29. Find the contents of the wedge, base 20 feet by 30 feet, height 10 feet, edge 15 feet.

30. State the prismoidal formula; would you use it in calculating earthwork?

31. Is a simple question in calculating areas.--Ed. _Eng. News_.

32. How many and what parts of a plane triangle must be given to find the rest?

33. Define the terms sine, co-sine, tangent, and co-tangent.

34. What are natural sines, co-sines, etc.?

35. What is a table of logarithmic sines, co-sines, etc.?

30. Two sides and two angles of a plane triangle being given, how do you find the other parts?

37. When two sides of a plane triangle and their included angles are given, how do you find the other parts?

38. In the right-angled triangle, A B H express algebraically the value of the sine, co-sine, tangent, and co-tangent of angle A in terms of a, b, and h, they being the altitude, base, and hypothenuse of the triangle.

39. What is the law of gravitation?

40. Do you understand that there is any difference in the meaning of the terms gravitation and gravity?

41. What is the law of falling bodies?

42. Express algebraically this law, taking v = velocity of falling body; g = acceleration of gravity; and h = height.

43. What is the center of gravity of a body?

44. How is it found?

45. Where is the center of gravity of a homogeneous body whose sides are all rectangles?

46. What is the specific gravity of a body?

47. What is the standard for solids and liquids?

48. What for gases?

49. What laws govern the pressure of liquids at rest?

50. How do you find the number of gallons of water to the cubic foot?

51. What is the weight of a gallon of water?

52. What is the pressure per square inch on the side of a vessel at the depth of 10 feet below the surface of the water?

53. What will be the theoretical volume of discharge per second from a reservoir through a pipe 1 foot in diameter, discharging at a depth of 100 feet below the surface of the water?

54. How many gallons of water will be discharged through a pipe 1 foot in diameter, 328 feet long, head 13½ feet, coefficient of flow = 0.007?

55. State how many men are needed to make up a full party for a survey of a preliminary line or location of a public work, such as a railroad or aqueduct.

56. State also their several duties.

57. For what purpose is the magnetic needle used in surveying land?

58. What is a traverse table and for what used?

59. How do you set out a circular curved line upon the ground?

60. If an obstacle occurs to alignment, state how you would overcome it upon straight lines, also upon curves.

61. The radius of a curve being given, and angle of intersection of the two tangents, how do you find the length of the tangent from their intersection to the beginning of the curve?

62. Describe an engineer's transit, and name its adjustments.

63. Describe a Y level, and name its adjustments.

64. How many kinds of leveling rods do you know of?

65. State how they are graduated, and how they can be read to the 1/1000 of a foot.

66. Show a form of field-book for transit notes used when "running" curves, and place thereon notes of a 5 deg. curve for 1,000, with two intermediate "set-ups."

67. Show a form of level-book, and place therein sufficient figures to show your method.

68. What are cross-sections?

69. How do you set slope stakes for excavation and embankment?

70. What is a grade line?

71. What proportion of the breaking weight of a beam would you consider a safe load?

72. With the load uniformly distributed, what fractional part of the whole weight may be considered, in all calculations, as being carried at the center?

73. Suppose a beam supported at both ends, and take w = weight, l = length of beam, b = breadth, d = depth, s = breaking weight. Express algebraically the value of s in terms of the other quantities.

74. Sectional area being 36 square inches, which would be the stronger section, 6 by 6 or 4 by 9?

75. Make a design for a pair of rafters, connected by a tie-beam, for a roof 30 feet span, showing the dimensions of the several parts and the manner of connecting them. State in detail your method of obtaining the several dimensions.

76. How do you apply the principle of the parallelogram of forces in determining the strain on the various members of a structure? Illustrate graphically.

77. What should be the thickness at the top and base of a retaining wall 15 feet high, built to retain ordinary earth? Show your method of obtaining the required dimensions, also a sketch of the wall, showing how it should be founded.

78. A reservoir is to be built, depth of water 10 feet. If the walls are built of masonry, find the thickness of the same, and state how they should be built. Show your work.

79. What is an arch, of how many forms, and of what may it be constructed?

80. Can you state how you would find the thickness of an arch of stone, span and rise being given?

81. Define the intrados and extrados of an arch.

82. Where should the line of resistance to pressure be found in an arch in order to retain its stability?

83. Can you find the thickness of the abutments, the rise and span of the arch being given?

84. In a semicircular arch, where is the horizontal thrust greatest and where least?

85. Name the common kinds of stone used in building.

86. Define the terms "quarry-faced," "rough-pointed," "fine-axed," "bush-hammered," as applied to the dressing of stone.

87. Describe "rubble" masonry, "ashlar" masonry, and "broken ashlar" masonry.

88. What are "headers" and "stretchers"?

89. What should be the proportion of "headers" to "stretchers"?

90. How would you prepare the foundation for a heavy wall, and how deep should it be excavated?

91. How are walls founded on soft or yielding materials?

92. Describe a good quality of bricks, and state how you would know a good brick from a poor one.

93. In how many ways is brickwork "bonded" to make good work in heavy walls?

94. What is hydraulic cement, and how many kinds do you know of?

95. Which do you consider the better quality, Rosendale or Portland, and why?

96. What is mortar composed of, and how mixed?

97. What kind of sand should be used, and how do you test its quality?

98. What is the meaning of the term "setting" as applied to cement?

99. How would you test cement?

100. What is concrete, of what composed, and in what proportion should its ingredients be mixed?

101. Name the common kinds of wood used in building.

102. What kind of timber resists decay longest under ground?

103. How may timber be preserved from decay?

104. What do you understand by limit of elasticity as applied to a beam under strain or pressure? What is meant by the neutral axis of a beam?

105. What is the tensile strength of a good quality of wrought iron per square inch?

106. For what parts of a structure may cast and wrought iron be used in reference to tension and compression?

107. Make a sketch of the form of cast-iron beam best adapted to resist a transverse strain.

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CELEBRATION OF THE FIVE HUNDREDTH ANNIVERSARY OF THE UNIVERSITY OF HEIDELBERG, AUGUST, 1886.

The wave of pleasure and enjoyment which flooded everything has passed. Heidelberg, usually so quiet, assumed the role of a city of the world, and all was bustle and excitement in the streets, which were hung with flags and other decorations. The trains constantly brought new accessions to the crowd, and gayety and mirth reigned supreme.

The dedication of the renovated _Aula_ of the University served as a prelude to the festivities of the week. On this occasion a splendid flag, embroidered by order of the wives of the faculty of the Academy, an equally costly cover for the scepter, and a silver inkstand were added to the treasures of the University. Conspicuous among the numerous presents received were a richly carved set of furniture--the gift of former students from Switzerland--and all the publications of certain book dealers.

On the afternoon of August 2, the Grand Duke and Duchess arrived in Heidelberg, where they were received with much enthusiasm. They remained at the modest palace during the time of the jubilee, and whenever they appeared they were greeted with expressions of patriotism and love. On the evening of the 2d, the _Oberburgermeister_, Dr. Wilckens, extended a hearty welcome to the guests who had gathered in the over crowded hall. Vincenz Lachner conducted the musical part of the entertainment, which was charming. The German Crown Prince arrived early on the 3d, so as to accompany his royal cousins to the service in the beautifully decorated _Heiliggeistkirche_, on which occasion Prof. Bassermann spoke with great effect. At 11 o'clock, the Court appeared in the _Aula_, where the Grand Duke presided, in virtue of his office of "Rector Magnificentissimus." His address was followed by those of the Crown Prince; the _Prorector Geheimrath_, Dr. Bekker; Edward Zeller, of Berlin; Jules Zeller, of Paris; and others. In the evening the citizens and strangers were attracted to the _Jettenbühel_ by the festival at the castle; from 7:30 until 10 o'clock the nobility held court in the _Bandhause_. The scene was like fairyland, all the outlines of the castle were marked by thousands of small lights, and the court was lighted by great candelabra. In the ever-increasing crowd it was difficult to find a place and to obtain refreshments, which were given out in immense quantities by the State.

On the morning of the 4th the people thronged again to the _Heiliggeistkirche_ to listen to the address of the _Geheimrath_, Dr. Kuno Fischer, on the fate of the Palatinate and Heidelberg, which was preceded and followed by music. After this the participants in the festival were brought together by a dinner in the Museum Hall, and seldom have speeches so inspired an audience as did those of the Grand Duke and the Crown Prince. Never has Heidelberg seen such a torch-light procession as that formed by the students in honor of their Rector; 3,000 torches lighted him to the City Hall. He thanked them, and proposed cheers for the Crown Prince.

On the morning of the 5th there was the presentation of degrees. In the afternoon a special train carried four hundred people to Karlsruhe, where the royal party held a great reception. The capital was decorated with flags, the city parks were lighted with Bengal lights, there was music, and a song by the patriotic bard Vierordt was sung.

All the splendor and interest shrank into insignificance before the grand historical procession on the morning of the 6th, which made a lasting impression on the minds of all. The throng of 100,000 people watched quietly while the whole history of the Palatinate passed in review before them. The procession illustrated this history much better than it could have been told by any professor or any book. There was not a vacant space to be found, extra trains having brought more spectators, and yet everything passed off quietly and without accident. In the evening there was a heavy shower, which freshened everything, leaving no ill effects to be seen the next morning, which was more than could be said of many of those who attended the imposing _Commerse_ of the Heidelberg students. As a former student, the Grand Duke appeared among the 6,000 visitors at the _Commerse_, where he presided and spoke enthusiastically of the Emperor. Other speeches followed, until the conversation became so animated that even Von Treitschke, who was received with an ovation, could not be heard. At midnight the court retired and the _Fidelitas_ succeeded to their rights.

On the 7th the time was spent in excursions and carousing until the illumination of the castle began. I never saw an illumination of the ruins which could compare in beauty with that of the 7th. The night was favorable for fireworks, until finally they were rivaled by the moon, numerous boats trimmed with colored lanterns passed along the river, there were fire-wheels on the bridge, water fireworks on the river, and the quiet was disturbed alternately by the rockets and music, and when the names of the Grand Duke and Duchess, crowned with brilliant fire, appeared over the water, there was an involuntary outburst of enthusiasm. If the old Elector and Electoress could have been present at the closing entertainment of the jubilee, on the evening of the 8th, they would have rejoiced to see the new life brought to the ruins by their successor.--_Illustrirte Zeitung._

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MANUFACTURE OF LEATHER IN RUSSIA.

From this extensive paper it appears that the matters chiefly used in tanning are the bark of the oak, containing from 6.04 to 4.37 per cent. of tannin according to the season, that of willows, of the elm, and the birch. The leaves of the arbutus, employed in the governments of Kasan, Viatka, and Perm, contain about 16 per cent. of tannin, while the root of wild sorrel (_Rumex acetosella_) contains 12 per cent. For removing the hair from hides, a lye made from wood ashes is still employed. The softening of the leather is effected by means of the excrement of dogs, which acts on the leather by means of the biliary acid present, which forms with soda a kind of soap. After tanning, white Russia leather is coated with a mixture of tar and seal oil. Black Russia leather is dyed with alum, extract of sanders, and ferrous sulphate. Horse hides are tanned to a great extent for sole leather.--_M. Ryloff._

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IMPURITIES IN PHOTOGRAPHIC CHEMICALS, AND TESTS FOR SAME.

[Table referred to in a paper read before the Birmingham Photographic Society by G.M. JONES, M.P.S.]