The day proved uneventful and I paid no further attention to the warning letter. It seemed too preposterous to amount to anything.
Kennedy, however, with his characteristic foresight, as I learned afterwards, had not been entirely unprepared, though he had affected to treat the thing with contempt.
His laboratory, I may say, was at the very edge of the University buildings, with the campus back of it, but opening on the other side on a street that was ordinarily not overcrowded.
We got up as usual the next day and, quite early, went over to the laboratory. Kennedy, as was his custom, plunged straightway into his work and appeared absorbed by it, while I wrote.
"There IS something queer going on, Walter," he remarked. "This thing registers some kind of wireless rays—infra-red, I think,—something like those that they say that Italian scientist, Ulivi, claims he has discovered and called the 'F-rays.'"
"How do you know?" I asked, looking up from my work. "What's that instrument you are using?"
"A bolometer, invented by the late Professor Langley," he replied, his attention riveted on it.
Some time previously, Kennedy had had installed on the window ledge one of those mirror-like arrangements, known as a "busybody," which show those in a room what is going on on the street.
As I moved over to look at the bolometer, I happened to glance into the busybody and saw that a crowd was rapidly collecting on the sidewalk.
"Look, Craig!" I called hastily.