Destiny of the Republic - By Candice Millard Page 0,76

patient I have ever had. He obeys me to the letter in everything, and he never makes any complaints about my orders.” This quality above all others, Bliss believed, would serve Garfield well. As he had stressed to another reporter only a few days earlier, the president could not hope for better medical care. “If I can’t save him,” he said, “no one can.”

As he sat in his father-in-law’s house in Boston, surrounded by chattering children and a wife eager for his attention, Alexander Graham Bell’s mind was still churning. Since he had learned of the assassination attempt, he had been able to think of nothing but the president. “I cannot possibly persuade him to sit, just these days,” Mabel complained in a letter to her mother. “He is hard at work day and night … for the President’s benefit.”

Bell knew he could find the bullet. He just did not yet know how. His first thought was that he might be able to flood Garfield’s body with light. He had read about a patient in Paris whose tumor had been revealed when his doctors inserted an electric light in his stomach, setting him aglow “like a Chinese lantern.” After considering Garfield’s injury, “it occurred to me,” Bell wrote, “that leaden bullets were certainly more opaque than tumors.” Deciding to run a few quick tests, he asked his secretary to hold a bullet and a miniature light in his mouth. As he had hoped, Bell could clearly see the bullet, a dark shadow against the young man’s illuminated cheek.

In a simplistic way, the technique anticipated the medical X-ray. The problem was that, even if Bell used an intensely bright light in a darkened room, the bullet would have to be very near the surface to be discernible. If it was deep in his back, as Garfield’s likely was, hidden behind dense layers of tissue and organs, it would never be seen.

As Bell worried about the flaws in his initial idea, the answer suddenly came to him. What he needed was not a light, but a metal detector. The memory of an earlier invention, he would later write, “returned vividly to my mind.”

Four years earlier, while struggling to fend off interference from nearby telegraph wires, which were cluttering his telephone lines with their rapid clicking sounds, Bell had found an ingenious solution. The problem stemmed from the telegraph wires’ constantly changing magnetic field, which created, or induced, corresponding currents in the telephone wires. Bell realized that if he split the telephone wire in two and placed one wire on each side of the telegraph line, the currents would cancel each other out. “The currents induced in one of the telephone conductors,” he would later explain, “were exactly equal and opposite to those induced in the other.” The technique, known as balancing the induction, left the line silent.

The idea had worked, and Bell had patented it in England that same year but had given it little thought since. Now, as he considered the president’s wound, he recalled that his tests in 1877 had shown him that his method of balancing induction could not only achieve a quiet line, it could detect metal. “When a position of silence was established,” he wrote, “a piece of metal brought within the field of induction caused the telephone to sound.”

After “brooding over the problem,” Bell realized that he could turn his system for reducing interference into an instrument for finding metal—the induction balance. He would loop two wires into coils, connecting one coil to a telephone receiver and the other to a battery and a circuit interrupter, thus providing the changing current necessary for induction. Then he would arrange the coils so that they overlapped each other just the right amount. He would know he had them perfectly adjusted when the buzzing sound in the receiver disappeared. If he then passed the coils over Garfield’s body, the metal bullet would upset the balance, and Bell would literally be able to hear it through the receiver. In this manner, the telephone, his most famous and frustrating invention, would “announce the presence of the bullet.”

Bell’s instincts told him that the induction balance would work, but he could not be certain until he tested it. Feeling frustrated and helpless in Boston, without his laboratory, his equipment, or his assistant, he once again turned to Charles Williams’s electrical shop, where he had met both Watson and Tainter, and where, just seven years earlier, he had built the first telephone. At “great