Following the 2013 revelations of Edward Snowden, Americans have come to realize that many of us may be under surveillance at any time. It all started 150 years ago on the battlefields of the Civil War, where each side tapped the other's telegraph lines. It continued in 1895, when the New York Police Department began to tap telephone lines. It was 20 years before it was public knowledge, and by then the NYPD was so busy tapping they had a separate...