"Here is your train coming in, sir," he merely said.

"We will let it go and wait for another. Is there a signal at either
end of the platform?"

"Yes, sir; at the further end."

"Let us walk towards it. Are there any of the porters or officials
about here?"

"No, sir; none."

"Take this ruler. I want you to go up the steps--there are steps up
the signal, by the way?"

"Yes, sir."

"I want you to measure the glass of the lamp. Do not go up any higher
than is necessary, but if you have to stretch be careful not to mark
off the measurement with your nail, although the impulse is a natural
one. That has been done already."

Parkinson looked apprehensively round and about. Fortunately the part
was a dark and unfrequented spot and everyone else was moving towards
the exit at the other end of the platform. Fortunately, also, the
signal was not a high one.

"As near as I can judge on the rounded surface, the glass is four and
seven-eighths across," reported Parkinson.