Donad M. Bliss.

Some of the most difficult problems encountered by the student of electrical science and industry present themselves at the very beginning of his studies, and their nature is indicated in the first questions he usually asks. What is electricity, what are the laws governing its action, and what are the terms so frequently used - volts, pressure, E.M.F., amperes, ohms, etc. ? Of the making of textbooks there is no end, and the student or amateur will find standard works in most well-equipped bookstores, at a moderate price, in which he will find these questions answered very fully. Unfortunately, however, the explanation of the various terms and rules are so frequently complicated by mathematics and pure theory, that unless the student has access to a properly equipped laboratory and the services of a skilled instructor, a great deal of tedious labor is necessary to enable him to reason intelligently and appreciate his first problems. These conditions are not usually within the reach of the amateur, and the so-called popular works on electricity are worthless as a real aid to his studies, being largely compiled from manufacturers' catalogues, with a smattering of information taken at random from obsolete works from which the copyright has long since expired.

We will endeavor in this series of articles to ■" make haste slowly," and to illustrate each principle or rule by simple but comprehensive experiments with apparatus made by the student himself, thus maintaining an even balance between theory and practice, and enabling the student to secure a clear understanding of electrical science as it exists to-dav.

To the question, "What is electricity?" no answer can be given. We know it only in the same way in which we recognize light and heat; namely, by the effects produced by its action. At this early stage it would be useless to examine in detail the theories most commonly accepted regarding the nature of electricity itself. We can only state that it is one form of the everlasting energy of nature, and displays itself to us as one member of the great trinity of natural forces - heat, light and electricity.

For many centuries electricity was only known in the impressive form, still exhibited in nature's laboratory by the thunderstorm, and in the feeble attraction of excited amber or resin for particles of paper or other light substances. The fact that this phenomenon of attraction was produced by' the same force that forms lightning, was not suspected or proved until comparatvely recent times.

The first and one of the most important facts to be noted by the student is that there is only one kind of electricity, and the difference between the lightning's flash and the feeble current generated by a single cell of battery is only one of degree; both effects being produced by the same force, the results differing only with the varying conditions in each case, and in direct accordance with well-known laws; The early experimenters conceived electricity to be a sort of fluid, and drew close distinctions between the various forms of electrical display with which they were familiar. Atmospheric electricity, frictional electricity, galvanic, and the electricity produced by earth currents, etc., were treated as though they were entirely separate forces. It is true that the action of electricity in many respects bears a striking similarity to the flow of fluids, and many of the terms and expressions used by the early scientists have been continued to the present time. As the purpose of these articles is to give the home student a practical knowledge of electricity as it is used in every-day life, as illustrated by the telephone, telegraph, electric light and power, electroplating, etc., the state of electrical action under high pressures, and known as static electricity, will not be taken up until a good start has been made in the' more important and useful branches of the science. Electrical action, whatever its form, is controlled by the amount of pressure, the quantity of current flowing, and the time in which such action takes place in any given circuit. The term circuit is applied to any electrical system allowing of a flow or circuit of electricity through its various parts. To take a familiar example: An electric-doorbell circuit is composed of a generator or battery, wires connecting the battery with the circuit-closer, or push-button, and the bell. The office of the pushbutton is to break or open the circuit at this point, so as to prevent the current flowing through the system and operating the bell until this contact is closed by pressing the button, when the current will at once flow through the circuit and operate the bell or signal. As stated above, the action of a current of electricity in such a circuit resembles in many respects the behavior of a fluid under pressure. It will assist the student to a better understanding of the laws governing electrical phenomena by examining the accompanying illustrations : In Fig. 1, A represents a force pump of any type, here shown as a rotary pump, and driven by any source of power. C is a water motor of the same type, and B and B' the pipes connecting the two machines. It is evident that if the pump A be driven so as to force water into the pipe B under sufficient pressure, the water motor C will revolve and may be used to furnish power, as indicated by the belt. It is also evident that all the water forced through the motor must return to the pump, so that a continual circulation of water takes place in the system so long as the pump is operated and the conditions remain unchanged. The water in the above case can only flow in one direction, as indicated by the arrows. If the pipes and apparatus are only strong enough to run under the moderate pressure of say 10 lbs. to the square inch, and the pump could be driven at a higher rate of speed, so as to keep a pressure of say 1,000 lbs., it is apparent that the pipes and joints, or the weakest point of the system, would soon begin to leak, and finally burst, and the water escape.

Studies In Electricity I 3Studies In Electricity I 4