The book is weak on explaining science and engineering. The figures are cut and pasted from patent applications of the late 19th century and they are not great for learning Electricity and Magnetism.
The publishers also gave the book a title that the body text contradicts. It seems to have been European scientists who invented the electrical age, not Tesla!
Among these scientists was Hans Christian Oersted, who in 1820 discovered a relationship between electricity and magnetism. Oersted connected a wire to a Voltaic pile and then placed a magnetic compass under the wire. To Oersted’s amazement, the compass needle was deflected only when he connected or disconnected the wire from the pile. Oersted’s experiments were repeated by André-Marie Ampere, who established that it was a flow of charge—a current—that was interacting with the magnetism of the needle and causing motion.
In 1831, Michael Faraday answered this question. Using a donut-shaped coil of wire and a bar magnet, Faraday demonstrated the laws of electromagnetic induction.
Faraday further realized the significance of Oersted’s observation that the compass needle was deflected only when the current was turned on or off; when the current was passing steadily through the wire, there was no deflection. Faraday hypothesized that both the magnet and the electric coil were each surrounded by an electromagnetic field (often depicted as a series of force lines) and that current or motion was produced when one of these fields was changing. When one turned the current on or off in Oersted’s wire, one energized or de-energized the field surrounding the wire, and this change interacted with the magnetic field surrounding the compass needle, causing the needle to swing. As we shall see, this realization that a changing field can induce a current or produce motion was essential for Tesla’s work on motors.
The author also credits Heinrich Hertz with the fundamentals behind radio communication.
What if we had to rely on the work of European engineers?
In Europe, though, AC was not forgotten, and inventors there improved the transformer; by winding two different coils on a single iron core, they found they could raise or lower the voltage of alternating current, and they quickly started using this new device in a variety of ways. For instance, in London in 1883, Lucien Gaulard and John Gibbs used one of the first transformers to connect both arc and different incandescent lights in series to a single large generator.29 About the same time in Budapest, the engineers Tesla had met at Ganz and Company—Zipernowski, Bláthy, and Déri (ZBD)—saw AC as a way of developing an incandescent lighting system that could serve a wider area. By having their generator produce high-voltage AC, they found they could distribute power over longer distances using small copper wires. To protect customers from the high voltage, they used a transformer to step down the voltage before the current came into homes and shops. Within a few years, the ZBD system was being used to light several European cities. Both the Gaulard and Gibbs and ZBD systems employed single-phase AC since that was all that was needed to secure the desired voltage change.
In other words, if no Americans had ever tinkered in this area, we’d have exactly the same system delivering power to our homes and offices.
How about the AC motor itself?
This brings us to Tesla’s third insight in the park. Based on his extensive mental engineering, Tesla had a hunch that somehow one or more alternating currents could be used to create a rotating magnetic field. If so, his thinking would have paralleled that of an English physicist, Walter Baily, who reported in 1879 how he had used two electric currents to cause Arago’s wheel to rotate. Instead of a horseshoe magnet, Baily placed four electromagnets underneath his copper disk (see Figure 2.9). Baily linked the coils in series, joining one with the other diagonally across from it. He then connected each pair of electromagnets to a rotating switch that controlled the current delivered from two separate batteries to the pairs of electromagnets. As Baily rotated his switch, the electromagnets were sequentially energized to become either north or south magnetic poles, with the effect that the magnetic field underneath the copper disk rotated. As a scientist, Baily seems to have been satisfied to know that electric currents could be used to turn Arago’s wheel, and he regarded his motor as a scientific toy.
1884 was a year in which no human being was illegal and Tesla emigrated to the U.S.:
Years later he recalled that process of formally entering the United States consisted of a clerk barking at him, “Kiss the Bible. Twenty cents!” Having lived in the cosmopolitan cities of Prague, Budapest, and Paris, Tesla was initially shocked by the crudeness and vulgarity of America. As he wrote in his autobiography, “What I had left was beautiful, artistic, and fascinating in every way; what I saw here was machined, rough, and unattractive. A burly policeman was twirling his stick which looked to me as big as a log. I approached him politely, with the request to direct me [to an address]. ‘Six blocks down, then to the left,’ he said, with murder in his eyes. ‘Is this America?’ I asked myself in painful surprise. ‘It is a century behind Europe in civilization.’
Tesla was quickly successful, selling patents on AC motors to Westinghouse in 1888 and earning roughly $90,000 for himself. What would $90k have been worth?
In late September, Tesla switched from the Astor House to the Gerlach Hotel on 27th Street, between Broadway and Sixth Avenue. Built in 1888 at a cost of $1 million, the Gerlach was an imposing eleven-story fireproof building that featured elevators, electric lights, and several sumptuous dining rooms.
I.e., Tesla earned enough to fund construction of one entire floor of a massive hotel in Manhattan.
He was a fantastic showman:
To help the audience appreciate the full potential of high-frequency AC for electric lighting, Tesla offered a breathtaking demonstration (Figure 7.2). Two large zinc sheets were suspended from the ceiling about fifteen feet from each other and connected to the oscillating transformer. With the auditorium lights dimmed, Tesla took a long gas-filled tube in each hand and stepped between the two sheets. As he waved the slender tubes, they glowed, charged by an electrostatic field set up between the plates. As Tesla explained, high-frequency current now made it possible to have electric lighting without wires, to have lamps that could be moved freely around a room.
From London, Tesla traveled on to Paris and booked a room in the Hotel de la Paix. On 19 February he gave a lecture before the Société de Physique and the Société International des Electriciens (Figure 8.3). Finding his demonstrations highly persuasive, the French electrician Édouard Hospitalier observed, “The young scientist is … almost as a prophet. He introduces so much warmth and sincerity into his explanations and experiments that faith wins us, and despite ourselves, we believe that we are witnesses of the dawn of a nearby revolution in the present processes of illumination.” Just as in London, Tesla’s performance generated a great deal of excitement and praise. “The French papers this week are full of Mr. Tesla and his brilliant experiments,” reported the Electrical Review. “No man in our age has achieved such a universal scientific reputation in a single stride as this gifted young electrical engineer.”
What did it cost to attend?
In St. Louis, Tesla lectured in the Exhibition Theater, which seated four thousand, but the hall was packed to suffocation as another several thousand people crowded in, most of whom came hoping to see Tesla’s spectacular demonstrations. The demand for seats was so great that tickets were being scalped outside the hall for three to five dollars.
We forget how unstable the U.S. economy was back then. The Panic of 1893 nearly put the new electric companies out of business and certainly wiped out a lot of shareholders even when the companies continued to operate.
The next post will talk about Tesla’s attempts to come up with a Second Act.