Scientific American Supplement, No. 794, March 21, 1891 by Various

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[Illustration]

SCIENTIFIC AMERICAN SUPPLEMENT NO. 794

NEW YORK, March 21, 1891

Scientific American Supplement. Vol. XXXI., No. 794.

Scientific American established 1845

Scientific American Supplement, $5 a year.

Scientific American and Supplement, $7 a year.

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TABLE OF CONTENTS

I. BOTANY.--New Race of Dwarf Dahlias.--A new and valuable
flowering plant, with portrait of the introducer.--1 illustration.

II. CHEMISTRY.--Carbon in Organic Substances.--By J. MESSINGER.--
An improved method of determining carbon by inorganic
combustions.--1 illustration.

III. CIVIL ENGINEERING.--A New Integrator.--By Prof. KARL
PEARSON. M.A.--An apparatus for use for the engineer in working
up areas, indicator diagrams, etc.--4 illustrations.

Best Diameter of Car Wheels.--The size of car wheels from the
standpoint of American engineering.--A plea for a moderate sized
wheel.

Improved Overhead Steam Traveling Crane.--A crane constructed
for use in steel works.--Great power and range.--3 illustrations.

Some Hints on Spiking Track.--A most practical article for telling
exactly how to conduct the operation on the ground.--1 illustration.

IV. ELECTRICITY.--Electrical Laboratory for Amateurs.--By GEO.
M. HOPKINS.--A simple collection of apparatus for conducting a
complete series of electrical experiments.--17 illustrations.

The Action of the Silent Discharge on Chlorine.--How an electric
discharge affects chlorine gas.--An important negative result.

V. ETHNOLOGY.--Some Winnebago Arts.--An interesting article
upon the arts of the Winnebago Indians.--A recent paper before
the New York Academy of Sciences.

VI. MEDICINE AND HYGIENE.--The Philosophy of Consumption.
--By Dr. J.S. CHRISTISON.--A review of the present theories of
consumption, and the role played in it by its bacillus.

VII. MUSIC.--Spacing the Frets on a Banjo Neck.--By Prof. C.W.
MACCORD.--A most practical treatment of this subject, with full
explanations.--1 illustration.

VIII. ORDNANCE.--High Explosives in Warfare.--By Commander
F.M. BARBER, U.S.N.--An elaborate review of modern explosives
in their applicability to ordnance, etc.

The Experiments at the Annapolis Proving Grounds.--The recent
tests at Annapolis described and illustrated.--Views of the
projectiles, plates, etc.--3 illustrations.

IX. PHYSICS.--Araeo-Picnometer.--An entirely novel form of hydrometer,
of very extended use and application.--1 illustration.

X. TECHNOLOGY.--Fabric for Upholstery Purposes.--Full technical
description of the method of producing a new and characteristic
fabric.--1 illustration.

Gaseous Illuminants.--By Prof. VIVIAN B. LEWES.--Continuation
of this important article, treating of the water gas and special
processes, with analyses.

Glove Making.--Early history of glove making in America.--Its
present aspects and processes.

Reversible Ingrain or Pro-Brussels Carpet.--An imitation of
Brussels carpet on the Ingrain principle.--Full description of the
process of making.--3 illustrations.

The Manufacture and Use of Plaster of Paris.--An excellent
treatment of a subject hitherto little written about.--Full
particulars of the manufacturing process.

* * * * *

IMPROVED OVERHEAD STEAM TRAVELING CRANE.

We show in Fig. 1 a general view, and in Figs. 2 and 3 a side
elevation and plan of an overhead steam traveling crane, which has
been constructed by Mr. Thomas Smith, of Rodley, near Leeds, for use
in a steel works, to lift, lower, and travel with loads up to 15 tons.
For our engravings and description we are indebted to _Industries._
The crane is designed for hoisting and lowering while traveling
transversely or longitudinally, and all the movements are readily
controlled from the cage, which is placed at one end of and underneath
the transverse beams, and from which the load can be readily seen. All
the gear wheels are of steel and have double helical teeth; the shafts
are also of steel, and the principal bearings are adjustable and
bushed with hard gun metal. This crane has a separate pair of engines
for each motion, which are supplied with steam by the multitubular
boiler placed in the cage as shown. The hoisting motions consist of
double purchase gearing, with grooved drum, treble best iron chain
with block and hook, driven by one pair of 8 in. by 12 in. engines.
The transverse traveling motion consists of gearing, chain, and
carriage on four tram wheels, with grooved chain pulleys, driven by
the second pair of 6 in. by 10 in. engines, and the longitudinal
traveling motion driven by the other pair of 8 in. by 12 in. engines.
The transverse beams are wrought iron riveted box girders, firmly
secured to the end carriages, which are mounted on four double flanged
steel-tired wheels, set to suit a 38 foot span.

[Illustration: IMPROVED OVERHEAD TRAVELING CRANE]

[Illustration: FIG. 2 SIDE ELEVATION]

[Illustration: FIG. 3 PLAN]

* * * * *

BEST DIAMETER CAR WHEELS.[1]

[Footnote 1: By Samuel Porcher, assistant engineer motive power
department, Pennsylvania Railroad. Read at a regular meeting of the
New York Railroad Club, Feb. 19, 1891.]

It goes almost without saying that for any given service we want the
best car wheel, and in general it is evident that this is the one best
adapted to the efficient, safe and prompt movement of trains, to the
necessary limitations improved by details of construction, and also
the one most economical in maintenance and manufacture.

It is our aim this afternoon to look into this question in so far as
the diameter of the wheel affects it, and in doing it we must consider
what liability there is to breakage or derangement of the parts of the
wheel, hot journals, bent axles, the effect of the weight of the wheel
itself, and the effect upon the track and riding of the car, handling
at wrecks and in the shop, the first cost of repairs, the mileage,
methods of manufacture, the service for which the wheel is intended
and the material of which it is made.

Confining ourselves to freight and passenger service, and to cast iron
and steel wheels in the general acceptation of the term as being the
most interesting, we know that cast iron is not as strong as wrought
iron or steel, that the tendency of a rotating wheel to burst is
directly proportional to its diameter, and that the difficulty of
making a suitable and perfect casting increases with the diameter.
Cast iron, therefore, would receive no attention if it were not for
its far greater cheapness as compared to wrought iron or steel. This
fact makes its use either wholly or in part very desirable for freight
service, and even causes some roads in this country, notably the one
with which I am connected, to find it profitable to develop and
perfect the cast iron wheel for use in all but special cases.

Steel, on the other hand, notwithstanding its great cost, is coming
more and more into favor, and has the great recommendations of
strength and safety. It is also of such a nature that wheels tired
with it run much further before being unfit for further service than
those made of cast iron, and consequently renewals are less frequent.
The inference would seem to be that a combination of steel and cast
iron would effect the desirable safeness with the greatest cheapness;
but up to the present this state of affairs has not yet been realized
to the proper extent, because of the labor and cost necessary to
accomplish this combination and the weakness involved in the manner of
joining the two kinds of material together.

Taking up the consideration of the diameter of the wheel now, and
allowing that on the score of economy cast iron must be used for
wheels in freight service, we are led to reflect that here heavy loads
are carried, and there is a growing tendency to increase them by
letting the floor of the car down to a level with the draft timbers.
All this makes it desirable to have the wheels strong and small to
avoid bent axles and broken flanges, to enable us to build a strong
truck, to reduce the dead weight of cars to a minimum, and have wrecks
quickly cleared away. The time has not yet come when we have to
consider seriously hot journals arising from high speed on freight
trains, and a reasonable degree only of easy riding is required. The
effect on the track is, however, a matter of moment. Judging from the
above, I should say that no wheel larger than one 33 in. in diameter
should be used under freight cars. Since experience in passenger
service shows that larger cast iron wheels do not make greater mileage
and cost more per 1,000 miles run, and that cast iron wheels smaller
than 33 in., while sometimes costing less per 1,000 miles run, are
more troublesome in the end, it is apparent that 33 in. is the best
diameter for the wheels we have to use in freight service.

When we take up passenger service we come to a much more difficult and
interesting part of the subject, for here we must consider it in all
its bearings, and meet the complications that varying conditions of
place and service impose. In consequence, I do not believe we can
recommend one diameter for all passenger car wheels although such a
state of simplicity would be most desirable. For instance, in a sandy
country where competition is active, and consequently speed is high
and maintained for a length of time without interruption, I would
scarcely hesitate to recommend the use of cast iron for car wheels,
because steel will wear out so rapidly in such a place that its use
will be unsatisfactory. If then cast iron is used, we will find that
we cannot make with it as large a wheel as we may determine is
desirable when steel is used. And just to follow this line out to its
close I will state here that we find that 36 in. seems to be the
maximum satisfactory diameter for cast iron wheels, because this size
does not give greater mileage than 33 in., costs more per 1,000 miles
run, and seems to be nearer the limit for good foundry results. On the
other hand, a 36 in. wheel rides well and gives immunity from hot
boxes--a most fruitful source of annoyance in sandy districts. It is
also easily applicable where all modern appliances under the car are
found, including good brake rigging. In all passenger service, then, I
would recommend 36 in. as the best diameter for cast iron wheels.

Next taking up steel wheels, a great deal might be said about the
different makes and patterns, but as the diameter of wheels of this
kind is not limited practically to any extent by the methods of
manufacture, except as to the fastening of the wheel and tire
together, we will note this point only. Tires might be so deeply cut
into for the introduction of a retaining ring that a small wheel would
be unduly weakened after a few turnings.

On the other hand, when centers and tires are held together by
springing the former into the latter under pressure, it is possible
that a tire of larger diameter might be overstrained. But allowing
that the method of manufacture does not limit the diameter of a steel
wheel as it does a cast iron one, the claim that the larger diameter
is the best is open to debate at least, and, I believe, is proved to
the contrary on several accounts. It is argued that increasing the
diameter of a wheel increases its total mileage in proportion, or even
more. Whether this be so or not, there are two other very
objectionable features that come with an increase in diameter--the
wheel becomes more costly and weighs more, without giving in all cases
a proportionate return. We have to do more work in starting and
stopping, and in lifting the large wheel over the hills, and when the
diameter exceeds a certain figure we have to pay more per 1,000 miles
run. I am very firmly convinced that the matter of dead weight should
receive more attention than it does, with a view to reducing it. The
weight of six pairs of 42 in. wheels and axles alone is 15,000 to
16,000 lb.

The matter of brakes is coming up for more attention in these days of
high speed, heavy cars and crowded roads, and the total available
braking power, which has hitherto been but partially taken advantage
of, must be fully utilized. I refer to the fact that many of our
wheels in six-wheel trucks have gone unbraked where they should not.
As the height of cars and length of trucks cannot well be increased
for obvious reasons, it is necessary to keep the size of the wheels
within the limits that will enable us to get efficient brakes on all
of them that carry any weight. This is not easy with a 42 in. wheel in
a six-wheel truck, which is usually the kind that requires most
adjustment and repairs after long runs. The Pullman Co. has recognized
this fact, and is now replacing its 42 in. wheel with one 38 in. in
diameter.

A 42 in. wheel with 4 in. journal has a greater leverage wherewith to
overcome the resistance of journal friction than the 38 in. wheel with
the same journal, and even more than the 36 in. and 33 in. wheels with
33/4 in. and 31/2 in. journals respectively, but the fact remains that the
same amount of work has to be done in overcoming the friction in each
case, and what may be gained in ease of starting with the large wheel
is lost in time necessary to do it, and in the extra weight put into
motion.

A large wheel increases the liability to bent axles in curving on
account of greater leverage unless the size and weight of the axle are
increased to correspond, and the wheel itself must be made stronger. A
four or six wheel truck will not retain its squareness and dependent
good riding qualities so well with 42 in. wheels as with 33 in. ones.
Besides the brakes, the pipes for air and steam under the cars
interfere with large wheels, and as a consequence of all this 42 in.
wheels have been replaced by 36 in. ones to some extent in some places
with satisfactory results. On one road in particular so strong is the
inclination away from large wheels that 30 in. is advocated as the
proper size for passenger cars.

On the other hand, there is no doubt a car wheel may be too small, for
the tires of small wheels probably do not get as much working up under
the rolls, and therefore are not as tough or homogeneous. Small wheels
are more destructive to frogs and rail joints. They revolve faster at
a given speed, and when below a certain size increase the liability to
hot journals if carrying the weight they can bear without detriment to
the rest of the wheel. Speed alone I am not willing to admit is the
most prolific source of hot boxes. The weight per square inch upon the
bearing is a very important factor. I have found by careful
examination of a great many cars that the number of hot boxes bears a
close relation to the weight per square inch on the journal and the
character of lubrication, and is not so much affected by the size of
wheel or speed. These observations were made upon 42 in., 36 in. and
33 in. wheels in the same trains. We find, furthermore, that while a
3-3/8 in. journal on a 33 in. wheel is apt to heat under our passenger
coaches, a 33/4 in., even when worn 3-5/8 in., journal on a 36 in. wheel
runs uniformly cool. In 1890 on one division there were about 180 hot
boxes with the small wheel, against 29 with the larger one, with a
preponderance of the latter size in service and cars of the same
weight over them.

I do not know that there is any more tendency for a large wheel to
slide than a small one under the action of the brakes, but large
wheels wear out more brake shoes than small ones, if there is any
difference in this particular.

My conclusions are that 42 in. is too large a diameter for steel
wheels in ordinary passenger service, and that 36 in. is right. But as
steel-tired wheels usually become 3 in. smaller in diameter before
wearing out, the wheel should be about 38 in. in diameter when new.
Such a wheel can be easily put under all passenger cars and will not
have become too small when worn out. A great many roads are using 36
in. wheels, but when their tires have lost 3 in. diameter they have
become 33 in. wheels, which I think too small.

There are many things I have left unsaid, and I am aware that some of
the members of the club have had most satisfactory service with 42 in.
wheels so far as exemption from all trouble is concerned, and others
have never seen any reason for departing from the most used size of 33
in.

One more word about lightness. A wrought iron or cast steel center, 8
or 9 light spokes on a light rim inside a steel tire, makes the
lightest wheel, and one that ought to be in this country, as it is
elsewhere, the cheapest not made of cast iron.

* * * * *

A NEW INTEGRATOR.[1]

[Footnote 1: A paper read before the University College Engineering
Society on January 22.--_Engineering_.]

BY PROFESSOR KARL PEARSON, M.A.

As I fear the title of my paper to our Society to-night contains two
misstatements of fact in its three words, I must commence by
correcting it. In the first place, the instrument to which I propose
to draw your attention to-night is, in the narrow sense of the words,
neither an integrator nor new. The name "integrator" has been
especially applied to a class of instruments which measure off on a
scale attached to them the magnitude of an area, arc, or other
quantity. Such instruments do not, as a rule, represent their results
graphically, and we may take, as characteristic examples of them,
Amsler's planimeter and some of the sphere integrating machines.

An integrator which draws an absolute picture of the sum or integral
is better termed an "integraph." The distinction is an important and
valuable one, for while the integraph theoretically can do all the
work of the integrator, the latter gives us in niggardly fashion one
narrow answer, _et praeterea nil_. The superiority of the integraph
over the integrator cannot be better pointed out than by a concrete
example. The integrator could determine by one process, the bending
moment, from the shear curve, at any one chosen point of a beam; the
integraph would, by an equally simple single process, gives us the
bending moment at all points of the beam.

In the language of the mathematician, the integrator gives only that
miserly result, a definite integral, but the integraph yields an
indefinite integral, a picture of the result at all times or all
points--a much greater boon in most mechanical and physical
investigations. Members of our Society as students of University
College have probably become acquainted with a process termed "drawing
the sum curve from the primitive curve." Many have probably found this
process somewhat wearisome; but this is not an unmixed evil, as the
irksomeness of any manual process has more than once led to the
invention of a valuable machine by the would-be idler. Thus our innate
desire to take things easy is a real incentive to progress. It was
some such desire as this on my part which led me, three years ago, to
inquire whether a practical instrument had not been, or could not be,
constructed to draw sum curves. Such an instrument is an integraph,
and the one I have to describe to you to-night is the outcome of that
inquiry. It is something better than my title, for it is an integraph,
and not an integrator.

[Illustration: A NEW INTEGRATOR]

Before I turn to its claims to be considered new, I must first remind
you of the importance of an instrument of this kind to the
draughtsman. I put aside its purely mechanical applications, where it
has been, or can be, attached to the indicators of steam engines, to
dynamometers, dynamos, and a variety of other instruments where
mechanical integration is of value. These lie entirely outside my
field, and I propose only to refer to a few of the possible services
of the integrator when used by hand, and not attached to a machine.

The simple finding of areas we may omit, as the planimeter will do
that equally well. But of purely graphical processes which the
integraph will undertake for us, I may mention the discovery of
centroids, of moments of inertia (or second moments), of a scale of
logarithms, of the real roots of cubic equations, and of equations of
higher order (with, however, increasing labor). Further, the
calculation of the cost of cutting and embanking for railways by the
method of Bruckner & Culmann, the solution of a very considerable
number of rather complex differential equations, various problems in
the storage of water, and a great variety of statistical questions may
all be completely dealt with, or very much simplified by aid of the
integraph.

In graphical statics proper the integraph draws successively the
curves of shear, bending moment slope, and deflection for simple
beams; it does the like service for continuous beams, after certain
analytical or graphical calculations have first been made; it can
further lighten greatly the graphical work in the treatment of masonry
arches and of metal ribs. In graphical hydrostatics it finds centers
of pressure and gives a complete solution for the shear and bending
moment, curves in ships, besides curves for their stability. In
graphical dynamics the applications of the integraph seem still more
numerous. It enables us to pass from curves of acceleration to curves
of speed, and from curves of speed to curves of position. Applied to
the curve of energy of either a particle or the index point of a rigid
body, it enables us by the aid of easy auxiliary processes to
ascertain speeds and curves of action. In a slightly altered form,
that of "inverse summation," we can pass from curves of action to
curves of position, and deal with a great range of resisted motions,
the analysis of which still puzzles the pure mathematician; the
variations of motion in flywheels, connecting rods, and innumerable
other parts of mechanism, may all be calculated with much greater ease
by the aid of an integraph. Shortly, it is the fundamental instrument
of graphic dynamics.

It would be needless to further multiply the instances of its
application; the questions we have rather to ask are: Can a practical
instrument be made which will serve all these purposes? Has such an
instrument been already put upon the market? If I have to answer these
questions in the negative, it is rather a doubtful negative, for the
instrument I have to show you to-night goes so far, and suggests so
many modifications and possibilities, which would take it so much
further, that it is very close to bringing the practical solution to
the problem.

Let me here lay down the conditions which seem essential to a
practical integraph. These are, I think, the following:

1. The price must be such that it is within the reach of the ordinary
draughtsman's pocket. The Amsler's planimeter at L2 10s. or L3 may be
said to satisfy this first condition. The price for the first complex
integraph designed by Coradi was L24 to L30. The modified form in
which I show it to-night is estimated to cost retail L14. Till an
equally efficient instrument can be produced for L5 I shall not
consider the price practical. If the error of its reading be not
sensibly greater than that of a planimeter, it is certainly worth
double the money.

2. The instrument must not be liable to get out of order by fair
handling and a reasonable amount of wear and tear. I cannot speak at
present with certainty as to how far our integraph satisfies this
condition; it is rather too complex to quite win my confidence in this
respect.

3. It must be capable of being used on the ordinary drawing board, and
of having a fairly wide range on it, i.e., it must not be limited to
working where the primitive is at one part only of the board.

This condition takes out of every day practical drawing use the
integraph invented by Professors James and Sir William Thomson, in
which the sum curve is drawn on a revolving cylinder. It is essential
that the sum curve should be drawn on the board not far from the
primitive, and that this sum curve can be summed once or twice again
without difficulty. The time involved in drawing the four sum curves,
for example, required in passing from the load curve to the deflection
curve of a simple beam, if these curves were drawn on different pieces
of paper and had to be shifted on and off cylinders, would probably be
as long as the ordinary graphical processes. Coradi's integraph works
on an ordinary drawing board, but since there are nearly 10 inches
between the guide point and tracer, the sum curve is thrown 10 inches
behind the primitive in each integration. Thus a double summation
requires say 26 inches of board, and it is impossible to integrate
thrice without reproducing the primitive. The fact that the primitive
and sum curve are not plotted off on the same base is also troublesome
for comparison, and involves scaling of a new base for each summation.
I have endeavored to obviate this by always drawing the second sum
curve on a thin piece of paper pinned to the board, which can then be
moved back to the position of the first primitive. But this shifting,
of course, involves additional labor, and is also a source of error.

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