Scientific American Supplement, No. 810, July 11, 1891 by Various
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Various >> Scientific American Supplement, No. 810, July 11, 1891
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SCIENTIFIC AMERICAN SUPPLEMENT NO. 810
NEW YORK, JULY 11, 1891
Scientific American Supplement. Vol. XXXII, No. 810.
Scientific American established 1845
Scientific American Supplement, $5 a year.
Scientific American and Supplement, $7 a year.
* * * * *
TABLE OF CONTENTS.
I. BOTANY.--Cocos Pynaerti.--A new dwarf growing palm.--1 illustration.
II. CHEMISTRY.--The Application of Electrolysis to Quantitative
Analysis.--By CHARLES A. KOHN, B.Sc., Ph.D.--Applicability of
these methods to poison determinations.
III. CIVIL ENGINEERING.--The Kioto-Fu Canal in Japan.--A
Japanese canal connecting the interior of the country with the
sea.--3 illustrations.
The Iron Gates of the Danube.--An important engineering work,
opening a channel in the Danube.--1 illustration.
The New German Ship Canal.--Connection of the Baltic with
the North Sea.--Completion of this work.--1 illustration.
Transit in London, Rapid and Otherwise.--By JAMES A. TILDEN.
--A practical review of London underground railroads and their
defects and peculiarities.
IV. ELECTRICITY.--An Electrostatic Safety Device.--Apparatus
for grounding a circuit of too high potential.--1 illustration.
Experiments with High Tension Alternating Currents.--Sparking
distance of arc formed by a potential difference of 20,000 volts.
--1 illustration.
Laying a Military Field Telegraph Line,--Recent field trials in
laying telegraph line in England.--3 illustrations.
Some Experiments on the Electric Discharge in Vacuum Tubes.
--By Prof. J.J. THOMSON, M.A., F.R.S.--Interesting experiments
described and illustrated.--4 illustrations.
The Electrical Manufacture of Phosphorus.--Note upon a new
English works for this industry.
V. GEOGRAPHY.--The Mississippi River.--By JACQUES W. REDWAY.
--An interesting paper on the great river and its work and
history.
VI. MECHANICAL ENGINEERING.--How to Find the Crack.--
Note on a point in foundry work.
Riveted Joints in Boiler Shells.--By WILLIAM BARNET LE
VAN.--Continuation of this practical and important paper.
--10 illustrations.
VII. MEDICINE AND HYGIENE.--Influence of Repose on the Retina.
--Important researches on the physiology of the eye.
The Relation of Bacteria to Practical Surgery.--By JOHN B.
ROBERTS, A.M., M.D.--A full review from the surgeon's standpoint
of this subject, with valuable directions for practitioners.
VIII. MINERALOGY.--Precious and Ornamental Stones and Diamond
Cutting.--By GEORGE FREDERICK KUNZ.--An abstract
from a recent census bulletin, giving interesting data.
IX. MINING ENGINEERING.--Mine Timbering.--The square system
of mine timbering as used in this country in the Pacific coast
mines and now introduced into Australia.--1 illustration.
X. MISCELLANEOUS.--Freezing Mixtures.--A list of useful freezing
mixtures.
Sun Dials.--Two interesting forms of sun dials described.
--3 illustrations.
The Undying Germ Plasm and the Immortal Soul.--By DR. R.
VON LENDENFELD.--A curious example of modern speculative
thought.
XI. NAVAL ENGINEERING.-The New British Battle Ship Empress
of India.--A first class battle ship recently launched at
Pembroke dockyard.
XII. TECHNOLOGY.--Composition of Wheat Grain and its Products
in the Mill.--A scientific examination of the composition of
wheat and its effect on mill products.
Fast and Fugitive Dyes.--By Prof. J.J. HAMMEL.--Practical
notes from the dyer's standpoint upon coloring agents.
* * * * *
MINE TIMBERING.
The square system of timbering, in use in most of our large mines on
the Pacific coast, was first introduced in Australia by Mr. W.H.
Patton, who adopted it in the Broken Hill Proprietary mines, although
it does not seem to be so satisfactory to the people there as to our
miners, who are more familiar with it. The accompanying description
and plans were furnished by Mr. Patton to the report of the Secretary
of Mines for Victoria:
"The idea is supposed to have originated in the German mines,
but in a crude form. It was introduced among the mines of the
Pacific coast of America some 20 years ago, by a gentleman
named Diedesheimer. Its use there is universal, and experience
has evolved it from the embryo state to its present
perfection. The old system and its accompanying disadvantages
are well known. A drive would be put in for a certain
distance, when it had to be abandoned until it could be filled
up with waste material and made secure. This process entailed
much expense. The stuff had first to be broken on the surface,
then sent below, trucked along the drives, and finally
shoveled into place. Ventilation was impaired and the drives
were filled with dust. The men worked in discomfort, and were
not in a condition to perform a full measure of labor. Under
the system as adopted in the Proprietary mine, these
disadvantages disappear. The cost is one-third less,
ventilation is perfect, and every portion of the faces are
accessible at all times. Sawn timber is used throughout; the
upright and cross pieces are 10 inches by 10 inches, and stand
4 feet 6 inches apart; along the course of the drive, the
cross pieces are five feet in length, and the height of the
main drives and sill floor sets are 7 feet 2 inches in the
clear. In blocking out the stopes, the uprights are 6 feet 2
inches, just one foot shorter than those in the main drives.
The caps and struts are of the same dimensions and timber as
the sill floor. The planks used as staging are 9 inches by 21/2
inches; they are moved from place to place as required, and
upon them the men stand when working in the stopes and in the
faces. A stope resembles a huge chamber fitted with
scaffolding from floor to roof. The atmosphere is cool and
pure, and there is no dust. Stage is added to stage, according
as the stoping requires it, and ladders lead from one floor to
the other; the accessibility to all the faces is a great
advantage.
If, while driving, a patch of low grade ore is met with, it
can be enriched by taking a higher class from another face,
and so on. Any grade can be produced by means of this power of
selection. Opinions have been expressed that this system of
timbering is not secure, and that pressure from above would
bring the whole structure down in ruins. But an opinion such
as this is due to miscomprehension of the facts. If signs of
weakening in the timbers become apparent, the remedy is very
simple. Four or more of the uprights are lined with planks,
and waste material is shot in from above, and a strong support
is at once formed, or if signs of crushing are noticed, it is
possible to go into the stope, break down ore, and at once
relieve the weight."
[Illustration: THE SQUARE SYSTEM OF TIMBERING IN MINES.]
* * * * *
TRANSIT IN LONDON, RAPID AND OTHERWISE.[1]
[Footnote 1: Abstract from a paper read before the Boston Society
of Engineers, in April, 1890.]
By JAMES A. TILDEN.
The methods of handling the travel and traffic in the city of London
form a very interesting subject for the study of the engineer. The
problem of rapid transit and transportation for a city of five
millions of inhabitants is naturally very complicated, and a very
difficult one to solve satisfactorily.
The subject may be discussed under two divisions: first, how the
suburban travel is accommodated, that is, the great mass of people who
come into the business section of the city every morning and leave at
night; second, how the strictly local traffic from one point to
another is provided for. Under the first division it will be noted in
advance that London is well provided with suburban railroad
accommodation upon through lines radiating in every direction from the
center of the city, but the terminal stations of these roads, as a
rule, do not penetrate far enough into the heart of the city to
provide for the suburban travel without some additional methods of
conveyance.
The underground railroad system is intended to relieve the traffic
upon the main thoroughfares, affording a rapid method of
transportation between the residential and business portions, and in
addition to form a communicating link between the terminals of the
roads referred to. These terminal stations are arranged in the form of
an irregular ellipse and are eleven in number.
One of the most noticeable features of the underground system in
London is that it connects these stations by means of a continuous
circuit, or "circle," as it is there called. The line connecting the
terminal stations is called the "inner circle." There is also an
extension at one end of this elliptical shaped circle which also makes
a complete circuit, and which is called the "middle circle," and a
very much larger circle reaching the northern portions of the city,
which is called the "outer circle." The eastern ends of these three
circles run for a considerable distance on the same track. In addition
to this the road branches off in a number of directions, reaching
those parts of the city which were not before accommodated by the
surface roads, or more properly the elevated or depressed roads, as
there are no grade crossings.
With regard to the accommodation afforded by this system: it is a
convenience for the residents of the western and southern parts of
London, especially where they arrive in the city at any of the
terminal stations on the line of the "circle," as they can change to
the underground. They can reach the eastern end of the "circle," at
which place is located the bank and the financial section of London,
in a comparatively short time. For example, passengers arriving at
Charing Cross, Victoria or Paddington stations, can change to the
underground, and in ten, fifteen and thirty minutes respectively,
reach the Mansion House or Cannon street stations, which are the
nearest to the Bank of England. In a similar manner those arriving at
Euston, St. Pancras or King's Cross on the northern side of the
"circle," can reach Broad Street station in ten or fifteen minutes,
which station is nearest the bank on that side of the "circle."
In a number of cases the underground station is in the same building
or directly connected by passages with the terminal stations of the
roads leading into the city. Examples of this kind would be such
stations as Cannon Street, Victoria or Paddington. They are not,
however, sufficiently convenient to allow the transference of baggage
so as to accommodate through passengers desiring to make connection
from one station to another across the city. Hand baggage only is
carried, about the same as it is on the elevated road in New York. The
method of cross town transfer, passengers and baggage, is invariably
done by small omnibuses, which all the railroads maintain on hand for
that special purpose. A very large proportion of the travel, however,
if not the largest, is obtained by direct communication by means of
the "circle" on branch lines with the various residential portions of
north, west and south London.
Approximately on the underground railroad the fare is one cent per
mile for third class, one cent and a half for second class, and two
cents for first class, but no fare is less than a penny, or two cents.
Omnibus fares in some instances are as low as a penny for two miles.
This is not by any means the rule, and is only to be found on
competing lines. The average fare would be a penny a mile or more.
The fares on the main lines which accommodate the suburban traffic are
somewhat higher than on the underground, perhaps 50 per cent. more. In
every case, on omnibus, tram cars or railroads, the rates are charged
according to distance. The system such as in use on our electric,
cable and horse cars and on the elevated road in New York, of charging
a fixed fare, is not in use anywhere.
The ticket offices of the underground roads are generally on a level
with the street. In some instances both the uptown and downtown trains
are approached from one entrance, but generally there is an entrance
at either side of the railroad, similar to the elevated railroad
system. In purchasing a ticket, the destination, number of the class,
and whether it is a single or return ticket have to be given. The
passenger then descends by generally well lighted stairways to the
station below, and his ticket is punched by the man at the gate. He
then has to be careful about two things; first, to place himself on
that part of the platform where the particular class which he wishes
to take stops, and secondly, to get on to the right train. In the
formation of the train the first class coaches are placed in the
center, the second and third class respectively at the front and rear
end. There are signs which indicate where passengers are to wait,
according to the class. There is a sign at the front end of the
engine, which to those initiated sufficiently indicates the
destination of the train. The trains are also called out, and at some
stations there is an obscure indicator which also gives the desired
information. The stations are from imperfectly to well lighted,
generally from daylight which sifts down from the smoky London
atmosphere through the openings above. The length of the train
averages about eight carriages of four compartments, each compartment
holding ten persons, making a carrying capacity of 320 passengers. The
equipment of the cars is very inferior. The first class compartments
are upholstered and cushioned in blue cloth, the second class in a
cheaper quality, while most of the third class compartments have
absolutely nothing in the way of a cushion or covering either on the
seat or back, and are little better than cattle pens. The width of the
compartment is so narrow that the feet can easily be placed on the
opposite seat, that is, a very little greater distance than would be
afforded by turning two of our seats face to face. The length of the
compartment, which is the width of the car, is about a foot and a half
less than the width of our passenger cars, about equal to our freight
cars. Each compartment is so imperfectly lighted by a single lamp put
into position through the top of the car that it is almost impossible
to read.
The length of time which a train remains at a station is from thirty
to forty seconds, or from three to four times the length of time
employed at the New York elevated railroad stations. The reason for
this is that a large proportion of the doors are opened by passengers
getting in or out, and all these have to be shut by the station porter
or guard of the train before the train can start. If the train is
crowded one has to run up and down to find a compartment with a vacant
seat, and also hunt for his class, and as each class is divided into
smoking and non-smoking compartments, making practically six classes,
it will be observed that all this takes time, especially when you add
the lost time at the ticket office and gate.
The ventilation of the tunnels and even the stations is oftentimes
simply abominable, and although the roads are heavily patronized there
is a great amount of grumbling and disfavor on this account. The
platforms of the stations are flush with those of the cars, so that
the delay of getting in or out is very small, but the doors are so low
that a person above the average height has to stoop to get in, and
cannot much more than stand upright with a tall hat on when he is once
in the car. The monitor roof is unknown.
The trains move with fair speed and the stations are plainly and
liberally marked, so that the passenger has little difficulty in
knowing when to get out. There are two signs in general use on English
railroads which are very simple and right to the point, namely, "Way
Out" and "Way In," so that when a passenger arrives at a station he
has no question how to get out of it. The ticket is given up as the
passenger leaves the station. There is nothing to prevent a passenger
with a third class ticket getting into a first class compartment
excepting the ominous warning of 40 shillings fine if he does so, and
the liability of having his sweet dreams interrupted by an occasional
inspector who asks to see the denomination of his ticket. All
compartments intended for the use of smokers are plainly marked and
are to be found in each class. Almost the entire part of the railroads
within the thickly settled portions of the city run in closed tunnels.
Outside of this they frequently run in open cuttings, and still
further out they run on to elevated tracks.
With regard to the equipment of the suburban or surface lines not
belonging to the underground system the description is about the same.
The cars are generally four compartments long and sometimes not
exceeding three. They are coupled together with a pair of links and
fastened to the draw bar on one car and the other thrown over a hook
opposite and brought into tension by a right and left hand screw
between the links. This is obviously very inconvenient for shunting
purposes, especially as the cars are not provided with hand brakes and
no chance to get at them if there were any. Consequently it appears
that when a train is made up it stays so for an indefinite period. A
load of passengers is brought into the station and the train remains
in position until it is ready to go out. As the trains run very
frequently this appears to be a very economical arrangement, as no
shunting tracks are needed for storage. The engine which brings the
train in of course cannot get out until the train goes out with the
next load. Turn tables for the locomotives are but very little used,
as they run as double enders for suburban purposes.
In conclusion it will be safe to say that the problem of rapid transit
for a city as large as London is far from solved by the methods
described. Although there are a great many miles of underground lines
and main lines, as they have been called throughout the paper, and
although grade crossings have been entirely abolished, allowing the
trains to run at the greatest speed suitable to their frequency, still
there are a great many sections which have to depend entirely upon the
omnibus or tram car. The enormous expense entailed by the construction
of the elevated structures can hardly be imagined. We have but one
similar structure in this country, which is that running from the
Schuylkill River to Broad Street station, in Philadelphia. The
underground system is even more expensive, especially in view of the
tremendous outlay for damages. This goes to show that money has not
been spared to obtain rapid transit.
After all, the means to be depended upon when one desires to make a
rapid trip from one part of the city to another is the really
admirable, cheap, always ready, convenient and comfortable London
hansom; while the way to see London is from the top of an omnibus, the
most enjoyable, if not the most expeditious, means of conveyance.
* * * * *
[Continued from SUPPLEMENT, NO. 809, page 12930.]
RIVETED JOINTS IN BOILER SHELLS.[1]
[Footnote 1: A paper read at a meeting of the Franklin Institute.
From the journal of the Institute.]
By WILLIAM BARNET LE VAN.
[Illustration: FIG. 11.]
Fig. 11 represents the spacing of rivets composed of steel plates
three-eighths inch thick, averaging 58,000 pounds tensile strength on
boiler fifty-four inches diameter, secured by iron rivets
seven-eighths inch diameter. Joints of these dimensions have been in
constant use for the last fourteen years, carrying 100 pounds per
square inch.
_Punching Rivet Holes._--Of all tools that take part in the
construction of boilers none are more important, or have more to do,
than the machine for punching rivet holes.
That punching, or the forcible detrusion of a circular piece of metal
to form a rivet hole, has a more or less injurious effect upon the
metal plates surrounding the hole, is a fact well known and admitted
by every engineer, and it has often been said that the rivet holes
ought all to be drilled. But, unfortunately, at present writing, no
drilling appliances have yet been placed on the market that can at all
compare with punching apparatus in rapidity and cheapness of working.
A first-class punching machine will make from forty to fifty holes per
minute in a thick steel plate. Where is the drilling machine that will
approach that with a single drill?
The most important matter in punching plates is the diameter of the
opening in the bolster or die relatively to that of the punch. This
difference exercises an important influence in respect not only of
easy punching but also in its effect upon the plate punched. If we
attempt to punch a perfectly cylindrical hole, the opening in the die
block must be of the same diameter as the point of the punch, or, at
least, a very close fit. The point of the punch ought to be slightly
larger in diameter than the neck, or upper part, as shown in Figs. 12
and 13, so as to clear itself easily. When the hole in the bolster or
die block is of a larger diameter than the punch, the piece of metal
thrust out is of larger diameter on the bottom side, and it comes out
with an ease proportionate to the difference between the lower and
upper diameters; or, in other words, it produces a taper hole in the
plate, but allows the punching to be done with less consumption of
power and, it is said, with less strain on the plate.
[Illustration: FIG. 12.]
[Illustration: FIG. 13.]
As to the difference which should exist between the diameter of the
punch and the die hole, this varies a little with the thickness of the
plate punched, or should do so in all carefully executed work, for it
is easy to understand that the die which might give a suitable taper
in a three-fourths inch plate would give too great a taper in a
three-eighths inch plate. There is no fixed rule; practical experience
determines this in a rough and ready way--often a very rough way,
indeed, for if a machine has to punch different thicknesses of plate
for the same size of rivets, the workman will seldom take the trouble
to change the die with every variation of thickness. The maker of
punches and dies generally allows about three sixty-fourths or 0.0468
of an inch clearance.
The following formula is also used by punch and die makers:
Clearance = D = d + 0.2t
where
D = diameter of hole in die block;
d = diameter of cutting edge of punch;
t = thickness of plate in fractions of an inch;
that is to say, the diameter of the die hole equals diameter of punch
plus two-tenths the thickness of the plate to be punched.
_Example_.--Given a plate 3/8 or 0.375 of an inch thick, the diameter
of the punch being 13/16 or 0.8125 of an inch, then the diameter of
the die hole will be as follows:
Diameter of die hole = 0.8125 + 0.375 X 0.2 = 0.8875 inch diameter,
or say 7/8 or 0.875 inch diameter.
Punches are generally made flat on their cutting edge, as shown in
Fig. 12. There are also punches made spiral on their cutting edge, as
shown in Fig. 13. This punch, instead of being flat, as in Fig. 12, is
of a helical form, as shown in Fig. 13, so as to have a gradual
shearing action commencing at the center and traveling round to the
circumference. Its form may be explained by imagining the upper cutter
of a shearing machine being rolled upon itself so as to form a
cylinder of which its long edge is the axis. The die being quite flat,
it follows that the shearing action proceeds from the center to the
circumference, just as in a shearing machine it travels from the
deeper to the shallower end of the upper cutter. The latter is not
recommended for use in metal of a thickness greater than the diameter
of the punch, and is best adapted for thicknesses of metal two-thirds
the diameter of the punch.
Fig. 14 shows positions of punch and attachments in the machine.
[Illustration: FIG. 14.]
It is of the greatest importance that the punch should be kept sharp
and the die in good order. If the punch is allowed to become dull, it
will produce a fin on the edge of the rivet hole, which, if not
removed, will cut into the rivet head and destroy the fillet by
cutting into the head. When the punch is in good condition it will
leave a sharp edge, which, if not removed, will also destroy the
fillet under the head by cutting it away.
Punching possesses so many advantages over drilling as to render it
extremely important that the operation should be reduced to a system
so as to be as harmless as possible to the plate. In fact, no plate
should be used in the construction of a boiler that does not improve
with punching, and further on I will show by the experiments made by
Hoopes & Townsend, of Philadelphia, that good material is improved by
punching; that is to say, with properly made punches and dies, by the
upsetting around the punched hole, the value of the plate is increased
instead of diminished, the flow of particles from the hole into the
surrounding parts causing stiffening and strengthening.
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