Electrical machine

“ It is not our purpose here to describe at length the electrical machine, but we may state that it consists of two parts, one for generating electricity by means of the friction of a rubber against glass, and another consisting of a system of brass tubes, of considerable surface, supported on glass stems, for collecting and retaining the electricity so produced. This latter part of the machine is called its prime conductor. ”

“ Having described the electrical machine, we are now to consider some of the phenomena attending its operation. When the prime conductor receives electricity from the cylinder, it is said to be electrified by communication, and it then acts in every respect like the cylinder itself, except that the latter, when touched by a conductor communicating with the earth, gives a considerable number of sparks before it is discharged; whereas the conductor discharges itself by a single spark. ”

“ CHAPTER LIII.—THE ELECTRICAL MACHINE, AND HOW TO MAKE IT. In our chapter on the Leyden Jar we assumed that those of our readers who were likely to experiment in frictional electricity would be in possession of an electrical machine to start with. Many, however, may be desirous of building an electrical machine of their own. ”

“ Replace it, and let the cylinder be again wiped; the machine is fit for use.
4. Sometimes the electric matter will not be well collected, because the machine is not sufficiently supplied with it from the earth; which happens, when the table upon which the electrical machine is placed and to which the chain or wire of the rubber is connected, is very dry, and consequently a bad conductor. In this case, the best method is to connect the chain or wire of the rubber with some moist ground, or with the iron-work of a water-pump, if convenient. ”

“ To milk cows by electricity is simply to apply the vacuum-cleaner idea to the process, and, in general, doing things by electricity usually means doing them by some machine that is made to go by an electric motor. This then is the first key to the Electrical Show, and if you will remember to look first for the motor it may remove much of the mystery from some of the exhibits. In many cases it is not necessary to have a complete electric motor, but simply an electro-magnet to do the work. ”

“ After demonstrating the practicability of this method of transmission, the thought naturally occurred to me to use the earth as a conductor, thus dispensing with all wires. Whatever electricity may be, it is a fact that it behaves like an incompressible fluid, and the earth may be looked upon as an immense reservoir of electricity, which, I thought, could be disturbed effectively by a properly designed electrical machine. Accordingly, my next efforts were directed toward perfecting a special apparatus which would be highly effective in creating a disturbance of electricity in the earth. ”

“ Fig. 175. The Leyden jar and brass wire discharger.
Thirty-sixth Experiment.
The jar is silently discharged if the balls are removed from the discharger and points used instead; so, also, the whole of the electricity produced by an electrical machine in full action may be readily drawn off by a pointed conductor, such as a needle, placed at the end of a brass wire. Electricity passes much more rapidly through points than rounded surfaces, hence the reason why all parts of electrical apparatus are free from sharp points and rough asperities. ”

“ On account of this very low electrical pressure all danger from the current is eliminated and the apparatus may be handled with the same freedom as any ordinary metal-working machine. In the distribution of the electrical appliances the current is usually generated by a machine conveniently located with reference to the source of power, and the current carried by wires to the welders, where the transformation takes place, each welder being provided with its own converter, proportioned so as to supply the character of current best suited to the special work of the machine. ”

“ In the specification of the patent which he took out for this machine in 1782 it is described as a ‘new invention and most usefull improvement in the common electrical machine (which I call the insulated medical electrical machine) by insulating the whole in a particular manner, and constructing the conductors so that either shocks or sparks may be received from them.’ Nairne published a description of this machine, which reached an eighth edition, in 1796. ”

“ In the case, therefore, of the electrical machine, it appears that the accumulation of electricity in an insulated conductor is always accompanied by the excitement of the contrary electricity in the surrounding atmosphere, and in every conductor placed near the former conductor. It does not seem possible, in this case, to produce one electricity by itself. ”

“ When but one of the machines is running, the idle machine is brought up to speed with the main switch open, and the voltage regulated by means of the rheostat and voltmeter until the voltages of the machines are the same. Then the main switch is thrown in and the load on the machines (which is ascertained by the ammeters) is equalized by means of the rheostats. Should there be any great difference in voltages, the higher one will run the other as a motor without changing the direction of rotation. ”

“ He showed that all substances could be electrified by friction, but that to electrify conductors they must be insulated or supported on non-conductors. Various improvements were made in the electrical machine, and thereby experimentalists were provided with the means of generating strong electrification ”

“ If an insulated conductor, connected with the positive conductor of an electrical machine, have a metal rod 0.3 of an inch in diameter projecting from it outwards from the machine, and terminating by a rounded end or a small ball, it will generally give good brushes; or, if the machine be not in good action, then many ways of assisting the formation of the brush can be resorted to ”

“ Observations of Faraday and Henry—Magneto-Electric Machines of Pixii and of Saxton—Hjorth’s Dynamo of 1855—Wilde’s Machine of 1866—Siemens’ of 1867—Gramme’s of 1870—Tesla’s Polyphase Currents.
In the last thirty-five years of the Nineteenth Century there has grown up into the full stature of mechanical majority this stalwart son of electrical lineage. As the means for furnishing electrical power it stands to-day the great fountain head of electrical generation, and in its peculiar field ranks as of equal importance with the steam engine. ”

“ The electrical machines in common use are composed of a hollow glass cylinder, or circular plate of glass, turning on an axis, and rubbing against two or more leather rubbers covered with silk, the electricity being collected by sharp points fixed in a metal rod standing on a glass pillar. ”

“ The framework of the machine is now complete, and we have to provide the glass plate from which the electricity is to be produced. As we cannot make this we must apply to an electrician for it. This is 10 inches in diameter. If the maker is good at, and has appliances for, working in brass on a small scale, he can make the axle himself by taking a [Pg 5] piece of brass rod 1⁄4 inch in diameter and 3 inches long and fastening the glass plate in the center. ”

“ Collecting Ring.
In some kinds of generators instead of the commutator a pair of
collecting rings of metal, insulated from the machine and from each
other, are carried on the armature shaft. A brush, q. v., presses on
each, and the circuit terminals connect to these two brushes. Such rings
are employed often on alternating current generators, where the current
does not have to be changed or commuted. Collecting rings with their
brushes are used also where a current has to be communicated to a
revolving coil or circuit as in the magnetic car wheel, the cut of which
is repeated here. ”

“ Any machine that can be used as a dynamo will, when supplied with electrical power, run as a motor, and conversely, a motor when driven by mechanical power, will supply electrical energy to the circuit connected to it. ”

“ However, Professor Wheatstone, having once taken in hand the production of electricity by an improved method, worked at the problem until he solved it. The electrical invention that ranks next in importance to the telegraph is the dynamo machine, and this also he had a share in introducing and improving. Its first conception has been claimed by different electricians. ”

“ As designed for power work and generally for lighting service, the brushes of each machine are set at the neutral point in order to get the best results for operating alternately either as a generator or motor. ”

“ Frictional electrical machines can be purchased from any electrical instrument makers, at a small price, and with these experiments mentioned are more readily performed. In this article I only mention experiments that can be performed with materials to be found in every house, or the necessaries for which can be procured from a shop for a nominal sum. ”

“ Vol. L. p. 329, also Hutton’s abridgments, Vol. XI. p. 149.
A.D. 1738.—Boze—Böse— (Georg Matthias) (1710–1761) , Professor of Philosophy at Wittemburg, publishes his “Oratio inauguralis de electricitate,” which is followed, in 1746, by “Recherches sur la cause et sur la véritable théorie de l’électricité,” and, in 1747, by his completed “Tentamina electrica.”
To him is due the introduction in the electrical machine of the prime conductor, in the form of an iron tube or cylinder. The latter was at first supported by a man insulated upon cakes of resin and afterward suspended by silken strings. ”

“ Contact surfaces forming part of electrical circuits must also be clean and tightly screwed together. An important point to bear in mind when assembling a machine is, to so place the parts that it will not be necessary to remove any one of them in order to get some other part in its proper position. ”

“ If this does not happen either the glass or some part of the machine is damp, or the machine is not put together quite correctly, and must be examined to find out the fault.
A machine of the size described should give a spark an inch long when working properly. A great number of experiments may be performed with this machine with appar [Pg 9] atus capable of being made at home. I give a final illustration (Fig. 6) to show how the machine looks when completed.
How to Make an Induction Coil. ”

“ The simplest form of an electric machine is one in which the operator is a prominent part of the operation. Electricity, like magnetism, operates in a closed circuit, even when it is static—so-called. Take a stick of sealing-wax, say, in your left hand, and rub it with a piece of fur or silk with your right hand, and you have the simplest form of electric machine—the one that was known to the ancients, and the one from which the science, great as it is to-day, had its beginnings. ”

“ To begin with, you all know that a piece of machinery is usually made to work by revolving a wheel which is part of the machine, either by means of a steam-engine or by water-power, or, as a sewing-machine, by foot-power. Now, when we work a piece of machinery by electricity we do just the same thing by using, instead of the steam-engine or water or foot power, an electric-engine called an "electromotor," which operates in the same way—namely, by turning the wheel of the machine it is applied to. ”

“ It is not our intention to say exactly how much is used on any one dynamo, because that is among the things you will have to learn when you come to study the subject of electricity more deeply.
We simply want to have you understand that upon the number of turns of wire on any one machine depends the effect that that amount of wire, carrying electricity, will have upon a certain weight of iron when the armature is revolved a certain number of turns per minute. ”

“ The machine gets charged after a few turns of the handle, and the operator feels that, as the charging progresses, it gets harder to turn the handle. In large machines the manual work becomes so heavy that it is convenient to use an electric motor for working the machine. ”

“ You light the burners on these machines as you light the gas, turn the electric switch and iron. It is quite simple and safe. Many of the machines have a pilot light to tell when the current (electric) is on or off. To heat by electricity all you do is to attach the cord to the ordinary wall socket.
A hand-power machine is driven by turning a handle. Thirty-five turns a minute is the right speed. It can be converted any time into a belt-driven machine and attached to the washing machine or anything else that goes by motor. ”

“ In mechanical appliances the new world has seemed to complete the inventions begun in the old world. Such was the case with the recording telegraph, the telephone, and the electric light. But in another class of inventions America did little or nothing. It was Europe that supplied the artificial generators of electricity. The voltaic pile, the thermo-electric pile, the Daniell and Grove batteries, and the dynamo machine were creations of the old world ”

“ We cannot pick up positive units of electricity from the ground as if they were pebbles and carry them by hand to the sphere; we must proceed in a different way. Let us then take a frictional machine and connect its negative wire to the ground, and the positive to the sphere. If the machine is worked, it will push negative electricity into the ground and positive on to the sphere. In other words, a charging current will flow along that wire, and more and more electricity will accumulate on the sphere the longer the machine is at work. ”