In the Boston telegraph office at that time, as perhaps at others, there were operators studying to enter college; possibly some were already in attendance at Harvard University. This condition was not unusual at one time; the first electrical engineer graduated from Columbia University, New York, followed up his studies while a night operator, and came out brilliantly at the head of his class. Edison says of these scholars that they paraded their knowledge rather freely, and that it was his delight to go to the second-hand book stores on Cornhill and study up questions which he could spring upon them when he got an occasion. With those engaged on night duty he got midnight lunch from an old Irishman called "the Cake Man," who appeared regularly with his wares at 12 midnight. "The office was on the ground floor, and had been a restaurant previous to its occupation by the Western Union Telegraph Company. It was literally loaded with cockroaches, which lived between the wall and the board running around the room at the floor, and which came after the lunch. These were such a bother on my table that I pasted two strips of tinfoil on the wall at my desk, connecting one piece to the positive pole of the big battery supplying current to the wires and the negative pole to the other strip. The cockroaches moving up on the wall would pass over the strips. The moment they got their legs across both strips there was a flash of light and the cockroaches went into gas. This automatic electrocuting device attracted so much attention, and got half a column in an evening paper, that the manager made me stop it." The reader will remember that a similar plan of campaign against rats was carried out by Edison while in the West.