they were to have greater speed on the Atlantic, there was one point
which was not alluded to in the paper, and that was the total
abolition of cargo on board the great passenger steamers. If vessels
were built solely for passenger traffic, they would be able to insure
greater speed by reason of the greater slightness in build and the
additional space at the command of the designer. The existing Atlantic
express steamer was far too heavy, and might, if cargo was dispensed
with, be made with finer lines and more yacht-like. He looked on the
proposition to fit such vessels with longitudinal bulkheads with great
fear. If a collision took place--such, for example, as that which sunk
the Oregon--water would get access to one side only of the ship, and
it was not at all improbable that if a sea was on, she would turn
right over. At all events, very serious risk would be involved.
Mr. W.H. White, Chief Constructor to the Admiralty, said the question
of twin screw propulsion was one of special interest to himself, and
had been so for many years. In 1878 he dealt with it as fully as he
then could on the basis of the Admiralty data, and he then ventured to
say everything in favor of twin screws that Mr. John had said in his
paper. If greater power than that now used in such a ship as the
Etruria, for example, were demanded, two screws must be used. Good as
are the results obtained with the Etruria, it was by no means certain
that still better might not be had. If she had been fitted with two
screws instead of one, very great advantage would be gained by the
greater submergence of the twin screws, as thus racing would be almost
wholly prevented.
Mr. Calvert urged that more attention should be devoted to studying
the relative values of different portions of the propeller.
The sitting was then suspended. In the afternoon, as we have already
stated, the members visited the steamship Germanic on the invitation
of Messrs. Ismay, Imrie & Co., subsequently proceeding to Messrs. Cope
Brothers' tobacco works, and thence to the exhibition, where the
dinner of the Institution took place in the evening.
On Friday morning no paper was read; some official business was
transacted, and this being done, the discussion on Mr. John's paper
was resumed.
Mr. Biles remarked that there were many advantages in the use of twin
screws which had not been sufficiently taken into account. When a ship
with twin screws was being handled in dock there was greater
maneuvering power, and therefore less liability for the ship to come
in contact with the walls, although, if she did so, there would be
greater probability of damage to the propellers. He thought means
could be easily devised of protecting the screws when the ship was in
dock. Another of the incidental advantages connected with twin screws
was that smaller engines and smaller propellers were required, and
therefore they might run them at a higher speed. They would also get
lighter machinery with twin screws, and there would be less liability
to have bad castings and forgings in the smaller engines, and of
course the cost would be less.
With respect to the question of the middle line bulkheads, he could
not quite agree with Mr. John as to the great advantages of them in a
big passenger steamer. He thought there would be greater difficulty in
managing a ship so built if she was in danger of sinking. Increased
subdivision in a longitudinal direction was a very desirable thing,
and almost necessary for a condition of immunity from sinking. In
future Atlantic steamers longitudinal bulkheads should be placed not
in the middle line, but nearer the sides of the ships, and they should
recognize the fact that they had engines and boilers in different
compartments, and make arrangements whereby the ship would still
float, although the doors in these compartments were kept open. The
proper way to arrive at that was to have a ship with great beam, and
to have two longitudinal bulkheads at considerable distances from the
sides of the ship, subdivided as completely as possible, both under
and above water, so that, even supposing they got water into the space
between one bulkhead and the side of the ship, they would have
sufficient buoyancy in the other parts of the ship to keep her afloat.
Broad ships must necessarily mean deep ships, in order to have comfort
at sea. They were limited in length, and first came the question how
many passengers they wanted to carry. The experience of a ship like
the America--which was only 400 ft. in length--showed it was not
necessary to go to great length to have great speed. A ship of 400 ft.
to 430 ft. in length, 65 ft. of beam, and with a depth of 45 ft.,
would be a ship of proper dimensions for the Atlantic trade, and he
believed it quite possible to build a vessel of special construction
of about 7,000 tons gross register which should steam with less
consumption of coal than the Umbria and Etruria at a rate of 22 knots,
crossing the Atlantic from Liverpool to New York in six days. He
thought that was likely to be the vessel of the future, and that it
would be quite as commercially successful as the Umbria or Etruria.
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.
* * * * *
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?
[Illustration]
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.
* * * * *
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._
* * * * *
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._
* * * * *
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.]