And I knew the immediate cause of that summons.

It was a rap of the knuckle by Ed Morrell, in Cell Five, beginning the spelling of some message.
And now, to give some comprehension of the extension of time and space that I was experiencing.

Many days afterwards I asked Morrell what he had tried to convey to me.

It was a simple message, namely: "Standing, are you there ?" He had tapped it rapidly, while the guard was at the far end of the corridor into which the solitary cells opened.

As I say, he had tapped the message very rapidly.