saw that his eyes
were no longer listless, as they had been a little before, but keen and
attentive and that they seemed to be watching, somewhere, in space, a
sight that apparently captivated them.

Meanwhile, he dictated, with intervals between each number:

"18, 9, 19, 11, 19 ..."

There was hardly anything to be seen through the window but a patch of
blue sky on the right and the front of the building opposite, an old
private house, whose shutters were closed as usual. There was nothing
particular about all this, no detail that struck me as new among those
which I had had before my eyes for years....

"1, 2...."

And suddenly I understood ... or rather I thought I understood, for how
could I admit that Lupin, a man so essentially level-headed under his
mask of frivolity, could waste his time upon such childish nonsense?
What he was counting was the intermittent flashes of a ray of sunlight
playing on the dingy front of the opposite house, at the height of the
second floor!

"15, 22 ..." said Lupin.

The flash disappeared for a few seconds and then struck the house again,
successively, at regular intervals, and disappeared once more.

I had instinctively counted the flashes and I said, aloud:

"5...."

"Caught the idea? I congratulate you!" he replied, sarcastically.

He went to the window and leant out, as though to discover the exact
direction followed by the ray of light. Then he came and lay on the sofa
again, saying:

"It's your turn now. Count away!"

The fellow seemed so positive that I did as he told me. Besides, I could
not help confessing that there was something rather curious about the
ordered frequency of those gleams on the front of the house opposite,
those appearances and disappearances, turn and turn about, like so many
flash signals.

They obviously came from a house on our side of the street, for the sun
was entering my windows slantwise. It was as though some one were
alternately opening and shutting a casement, or, more likely, amusing
himself by making sunlight flashes with a pocket-mirror.

"It's a child having a game!" I cried, after a moment or two, feeling a
little irritated by the trivial occupation that had been thrust upon me.

"Never mind, go on!"

And I counted away.... And I put down rows of figures.... And the sun
continued to play in front of me, with mathematical precision.

"Well?" said Lupin, after a longer pause than usual.

"Why, it seems finished.... T