Kennedy was quite apparently considering the honesty and faithfulness of the servant. At last he leaned over and asked quickly, "Can I trust you?"
The frank, "Yes," of the young fellow was convincing enough.
"What I want," pursued Kennedy, "is to have some one inside this house who can tell me as much as he can see of the visitors, the messengers that come here this morning. It will be an act of loyalty to your employer, so that you need have no fear about that."
Edward bowed, and left us. While I had been seeking him, Kennedy had telephoned hastily to his laboratory and had found one of his students there. He had ordered him to bring down an apparatus which he described, and some other material.
While we waited Kennedy sent word to Pitts that he wanted to see him alone for a few minutes.
The instrument appeared to be a rubber bulb and cuff with a rubber bag attached to the inside. From it ran a tube which ended in another graduated glass tube with a thin line of mercury in it like a thermometer.
Craig adjusted the thing over the brachial artery of Pitts, just above the elbow.
"It may be a little uncomfortable, Mr. Pitts," he apologised, "but it will be for only a few minutes."
Pressure through the rubber bulb shut off the artery so that Kennedy could no longer feel the pulse at the wrist. As he worked, I began to see what he was after. The reading on the graded scale of the height of the column of mercury indicated, I knew, blood pressure. This time, as he worked, I noted also
