OLICE-CONSTABLE HARRAP, a large and unimaginative man, watched with good-natured contempt the Application of Science to the Detection of Crime. He and Doctor Lomond were alone in Meister's room, and the doctor, with a long builder's tape, was taking careful measurements, sometimes requisitioning the police officer to hold the brass-looped end, sometimes dispensing with his services. On the blotting pad there was a sprinkle of red blots, as though somebody had been using ink of that colour and had shaken his pen over the table. This was the only evidence that remained of the tragedy which had been enacted less than an hour before. The ambulance had come and gone, and there remained only Constable Harrap in charge of the house, and this energetic amateur.
"A man's normal stride covers twenty-seven inches. A woman's covers twenty-two," said Doctor Lomond impressively.
"That's right, sir," said the constable, whose tone conveyed both agreement and a subtle admiration.
Not that Police-Constable Harrap had the slightest idea what was the normal stride of a man or woman. He thought little on the matter, and cared less. But he had learnt, through many years of service, never to disagree with his superiors.
Doctor Lomond took out his watch, clicked down the control of the chronograph, and stepped cautiously from the door to the desk, aimed an imaginary blow at an imaginary enemy in the chair, and looked at his watch again.
"Three seconds and two-fifths," he said, and jotted down his discovery.
Police-Constable Harrap, who hadn't the foggiest notion what it was all about, raised his eyebrows and looked impressed.
"On a job like this, sir," he said, "it's usual for the officer in charge to say to the constable: 'If you can find a bottle of beer about, help yourself, my lad, and don't be shy.' I'll bet old Meister—poor Mr. Meister," he corrected himself, "has got lashings of beer in the house. I've seen it come in by the case," he added mendaciously. And when the doctor, intent upon his calculations, took no notice: "Of course it's not usual to drink on duty, but a pint of beer never killed any man," said Constable Harrap. "And though I admit Mr. Wembury never mentioned anything about it, I shouldn't be surprised if he didn't say to himself, 'Well, if the constable wants a drink, then he'll mention it to the doctor, and maybe the doctor will prescribe—to use a medical term—a pint or two pints, as the case may be.'"
Doctor Lomond was scratching his chin.
"If we could only measure the distance between the door into the garden and the stable door"
"I'm not supposed to leave the house," said Harrap quickly. It was raining outside, and the wind was freshening again. "If I was allowed out in the street I could get a pint from the 'Pretty Maid.' The landlord suffers from insom—insumnia, and he's up day and night. We're not supposed to drink when we're on duty, but the Commissioners, being human men, wink at it, if you understand, Doctor?"
"Yes, yes," said Doctor Lomond impatiently.
Suddenly he started and looked up at the ceiling. Was it his imagination, or did he hear in the room above the sound of a stealthy footstep?
"Did you hear anything, Constable?"
Harrap looked up at the ceiling.
"I thought I heard something," he said cautiously. "Sounded like somebody dropping a bottle of beer"
"Don't be a fool!"
In three strides the doctor was across the floor. He ran up the stairs leading to Meister's bedroom, switched on the lights and went in. The window was wide open and the wind was blowing in the curtains. He took a look round the apartment, put out the lights and came thoughtfully down the stairs. The sound for the moment had distracted his attention from the serious business of criminal investigation. He wound up his tape, dropped it in his bag and closed the bag with a snap.
He was the reverse of nervous. And yet twice in the last half hour he had heard a queer sound, that he could not but associate with human movements.
"I'm going to see Mr. Wembury," he said shortly. "I'll leave my bag here."
"Mr. Wembury said he was coming back, sir, if you care to wait," Harrap told him. "The sergeant's going to make a search of the house. There ought to be some queer things found here. Personally," he added, "I'd like to have the job of searching the pantry or the wine cellar, or wherever he keeps the beer."