Inspector Jacks studied the brass plate for a moment, and then rang the patients’ bell.  The former, he noticed was very much in want of cleaning, and for a doctor’s residence there was a certain lack of smartness about the house and its appointments which betokened a limited practice.  The railing in front was broken, and no pretence had been made at keeping the garden in order.  Inspector Jacks had time to notice these things, for it was not until after his second summons that the door was opened by Dr. Whiles himself.

“Good morning!” the latter said tentatively.  Then, with a slight air of disappointment, he recognized his visitor.

“Good morning, doctor!” Inspector Jacks replied.  “You haven’t forgotten me, I hope?  I came down to see you a short time ago, respecting the man who was knocked down by a motor car and treated by you on a certain evening.”

The doctor nodded.

“Will you come in?” he asked.

He led the way into a somewhat dingy waiting room.  A copy of The Field, a month old, a dog-eared magazine, and a bound volume of Good Words were spread upon the table.  The room itself, except for a few chairs, was practically bare.

“I do not wish to take up too much of your time, Dr. Whiles,” the Inspector began,—­

The doctor laughed shortly.

“You needn’t bother about that,” he said.  “I’m tired of making a bluff.  My time isn’t any too well occupied.”

The Inspector glanced at his watch,—­it was a few minutes past twelve.

“If you are really not busy,” he said, “I was about to suggest to you that you should come back to town with me and lunch.  I do not expect, of course, to take up your day for nothing,” he continued.  “You will understand, as a professional man, that when your services are required by the authorities, they expect and are willing to pay for them.”

“But what use can I be to you?” the doctor asked.  “You know all about the man whom I fixed up on the night of the murder.  There’s nothing more to tell you about that.  I’d as soon go up to town and lunch with you as not, but if you think that I’ve anything more to tell you, you’ll only be disappointed.”

The Inspector nodded.

“I’m quite content to run the risk of that,” he said.  “Of course,” he continued, “it does not follow in the least that this person was in any way connected with the murder.  In fact, so far as I can tell at present, the chances are very much against it.  But at the same time it would interest my chief if you were able to identify him.”

The doctor nodded.

“I begin to understand,” he said.

“If you will consider a day spent up in town equivalent to the treatment of twenty-five patients at your ordinary scale,” Inspector Jacks said, “I shall be glad if you would accompany me there by the next train.  We will lunch together first, and look for our friend later in the afternoon.”