The Mysteries of Electricity

New Zealand Tablet, Volume XXXIII, Issue 17, 27 April 1905, Page 5

The Mysteries of Electricity

Now thja/t electricity is coming into sucfi general ufse in New Zealanld the following particulars regarding it, takeln *rom Uhe ' New Ydrk Press,' will be of interest : The generator is a prcrdjuscer of electricity and a niio^or is a consumer of the same ; and it is pemha|)S one of the most frea'kisih traits abdut tihe most freakish potential agetit— electricity— that the generator and motor may be duplicate machines, identical in every detail of construction, and can be used for either piurpose. An electric car can be stopped at amy point on the road, raised clear of tJhe tracks and its wheels tiurned rapidly by any available metihod. Its motors then become generators and will throw a powerful electric current back into the conducting wires, instead of absorbing it. Although the technicalities surrounding electrical industries are appalling to the average man, the principle of producing the current and adapting its energy to the various requirements of driving machinery and cars and of creating light is simple. Take a small rod of soft iron, wind around it a number of turns of fine insulated copjner wire and connect the enS of the wire to two plates of any electric battery and you have a (primitive eloctric plant. The little rod of iron becomes an electro magnet and attracts steel or iron as a common horseshoe magnet does. If a second rod is prepared in the same way and placed opposite the first the mutual attraction will be strong ; but if the wires connecting to the battery be changed about the direction of tihe current is changed, and the magnets repel instead of attracting each other. Suspend them so that they can move freely and arrange to change the current regularly and at the proper times and these rods will alternately attract and repel each other, and Miere is motion and power in an infinitesimal degree. Technically, it is a power plant,consisting of a chemical generator connected to an alternating current motor. Up to this point the greatest scientist _ Knows no More About the Causes ' of this motion than any man who is able to read these* lines. Why the chemical 'bath produces the electric current, what the current is and how it instantly transforms the iron into a magnet are mysteries which not even a Faraday, an Edison, or a Thompson attempt to explata. For many years efforts were made to obtain motion and power in the above m»anner which would be of pra<x

tidal uste. Electro-miagniets of large size were arranged in groups similarly to the spokes of a wheel, to revolve rapidly past each other ; but the large consumption of explosive chemicials in the batteries, with a correspondingly insignificant result in power, gave no encouragement fxom a commercial point of view, and it was not until the discovery that the battery could be entirely eliminated thiat the possibilities of electricity as a factor in tihe great industrial world appeared. Some time in the sixties Professor Henry gave his little sion, for a plaything, one of these experimental electoro-magnetic machines, which had been discarded as useless. No battery or chemicals accompanied the gift, so the little chap amused, himself by twirling the contrivance by 'hand. Tiring of this, he reached out for other worlds, and surreptitiously securing a galvonometer, one of the little instruments used by the professor for measuring current, he hooked on the wires im the way he had seen his father attach them, and continued his twirling. While he was engaged, the professor* arrived and, glancing at the galvonometer, was astonished to see indications of an electric current. Taking a hand in the twirling, he found Unmistakeabte Evidence that by ianiaiy revolving tnese magnets in front of each other an electric current of considerable energy was produced without the agency of an electric battery. The true generator had been found and the dawn of the electric age, wit|i all its miarvellous wealth of scientific and commercial exploitation and success opened. As an insitance of the scientific phraseology which confronts a srfudent, it may be noted that this simple discovery by a playful boy is diagnosed by Faraday as the liaw of electro-magpetic induction— that ' the electrical pressure generated in a coil of wire, by relative motion between it and a magnetic field, is directly proportional to the rate of change of interlinkages of turns and lines of force.' Crude and clumsy apparatus was quickly designed and built, and, on being btelted to a steam engine, gafe an amount of current which no instrument then in use could measure. These early generators were called dynamos and were used exclusively to produce arc lights. A few years later the discoveiry was made that if a duplicate generator was carried to any desired distance and connected with wires to the first, a corresponding rotation was obtained. The current generated in the first machine went over the wire to the second machine and operated it. TThis was another surprise. That its value was instantly appreciated is .shown by the fact that in Cleveland in 1884, without waiting to build new machines, two Brush arc light dynamos, which had 'done service for several years, were obtained. One wag connected to an engine in a convenient building, the other was attached to the axle of an old horse car. A wire was strung along the track arid the first electric car w&s commercially introduced, and electric traction and electric power were before A Wondering World. Upon this simple principle of one electro-magnet passing rapidly before another are built all electric light dynamos, great power generators, and motors of every description, from the tiny fan motor to the great 1200-horse-power railroad motors. The details of the larger machines are most complex, and the highest type ol scientific and mathematical knowledge has been engaged in determining the most efficient methods of winding the magnets and designing the machines to produce the quality and quantity of current required. For lighting purposes a current of moderate flow, but very high intensity, or voltage, is needed ; for power purposes a current of ample flow, but of moderate intensity is desirable. Electrical engineers are meeting all these shades of requirements witfh marvellous skill and ingenuity, but underlying it all is the mystery of the natmre of the current. They can evoke the giant, can direct its energy into a hundred channels, can control it with masterpieces of scientific and mechanical achievement, can destroy it ; but what it is remains unsolved. It is still the gi|eat unknown !