at Mr. Montagu Naylor, of "The Cedars,"
Apthorpe Road, was constantly receiving wrong calls.

This operator's report had been considered of sufficient importance to
send to Department Z. Instructions had been given for a complete
record to be kept of all Mr. Montagu Naylor's calls, in-coming and
out-going. The first thing that struck Sage as significant was that
all these false calls were made from public call-boxes. He gave
instructions that at the Streatham Exchange they were to enquire of the
exchanges from which the calls had come if any complaint had been made
by those getting wrong numbers. The result showed that quite a number
of people seemed content to pay threepence to be told that they were on
to the wrong subscriber.

"What do you make of it, Thompson?" Malcolm Sage looked up in that
sudden way of his, which many found so disconcerting.

Thompson shook his head. "I've had enquiries made at all the places
given, and they seem quite all right, sir," was his reply. "It's
funny," he added after a pause. "It began with short streets and small
numbers, and then gradually took in the larger thoroughfares with
bigger numbers."

"The calls have always come through in the same way?" queried Malcolm
Sage. "First the number and then the street and no mention of the
exchange."

"Yes, sir," was the response. "It's a bit of a puzzle," he added.

Malcolm Sage nodded. For some minutes they sat in silence, Sage
staring with expressionless face at the papers before him. Suddenly
with a swift movement he pushed them over towards Thompson.

"Get out a list of the whole range of numbers immediately, and bring it
to me as soon as you can. Tell them to get me through to Smart at the
Streatham Exchange."

"Very good, sir;" and the man took his departure.

A minute later the telephone bell rang.

Malcolm Sage took up the receiver. "That you, Smart?" he enquired, "re
Z.18, in future transcribe figures in words exactly as spoken, thus
double-one-three, one-hundred-and-thirteen, or one-one-three, as the
case may be." He jammed the receiver back again on to the rest, and
proceeded to gaze fixedly at the finger-nails of his left hand.

A quarter of an hour later Special Service Officer Thompson entered
with a long list of figures, which he handed to Malcolm Sage.

"You've hit it, Thompson," said Sage, glancing swiftly down the list.

"Have I, sir?" said Thompson, not quite sure what it was he was
supposed to