Sweetwater was too taken aback to answer immediately.  This was a move he did not understand.  Want it, he?  What he wanted was to see it put back in its place on the shelf.  Did Brotherson suspect this?  The supposition was incredible; yet who could read a mind so mysterious?

Sweetwater, debating the subject, decided that the risk of adding to any such possible suspicion was less to be dreaded than the continued threat offered by that unoccupied space so near the hole which testified so unmistakably of the means he had taken to spy upon this suspected man’s privacy.  So, after a moment of awkward silence, not out of keeping with the character he had assumed, he calmly refused the present as he had the glass.

Unhappily he was not rewarded by seeing the despised volume restored to its shelf.  It still lay where its owner had pushed it, when, with some awkwardly muttered thanks, the discomfited detective withdrew to his own room.

XVIII

WHAT AM I TO DO NOW

Early morning saw Sweetwater peering into the depths of his closet.  The hole was hardly visible.  This meant that the book he had pushed across it from the other side had not been removed.

Greatly re-assured by the sight, he awaited his opportunity, and as soon as a suitable one presented itself, prepared the hole for inspection by breaking away its edges and begriming it well with plaster and old dirt.  This done, he left matters to arrange themselves; which they did, after this manner.

Mr. Brotherson suddenly developed a great need of him, and it became a common thing for him to spend the half and, sometimes, the whole of the evening in the neighbouring room.  This was just what he had worked for, and his constant intercourse with the man whose secret he sought to surprise should have borne fruit.  But it did not.  Nothing in the eager but painstaking inventor showed a distracted mind or a heavily-burdened soul.  Indeed, he was so calm in all his ways, so precise and so self-contained, that Sweetwater often wondered what had become of the fiery agitator and eloquent propagandist of new and startling doctrines.

Then, he thought he understood the riddle.  The model was reaching its completion, and Brotherson’s extreme interest in it and the confidence he had in its success swallowed up all lesser emotions.  Were the invention to prove a failure—­but there was small hope of this.  The man was of too well-poised a mind to over-estimate his work or miscalculate its place among modern improvements.  Soon he would reach the goal of his desires, be praised, feted, made much of by the very people he now professedly scorned.  There was no thoroughfare for Sweetwater here.  Another road must be found; some secret, strange and unforeseen method of reaching a soul inaccessible to all ordinary or even extraordinary impressions.