What are the first two problems the narrator faces in "The Pit and the Pendulum"?

Poe's short story "The Pit and the Pendulum" begins with a rather ambiguous account of the narrator being sentenced to some form of punishment and losing consciousness.  Upon first regaining consciousness, the first problem he encounters is that he does not know where he is:

I felt that I lay upon my back, unbound. I reached out my hand, and it fell heavily upon something damp and hard. There I suffered it to remain for many minutes, while I strove to imagine where and what I could be. I longed, yet dared not to employ my vision. I dreaded the first glance at objects around me. It was not that I feared to look upon things horrible, but that I grew aghast lest there should be nothing to see. At length, with a wild desperation at heart, I quickly unclosed my eyes. My worst thoughts, then, were confirmed. The blackness of eternal night encompassed me.

From this exposition, we see that his senses are unable to tell him where he is.  Other than touching something "damp and hard" and seeing--if you can call it that--"the blackness of eternal night," he doesn't have any sense data from which to determine where he has been put for his punishment.

After groping around in the dark to deduce where he is and what his surroundings consist of, the narrator encounters his second problem: that there is a large pit in the center of the dungeon into which he has been thrown:

I put forward my arm, and shuddered to find that I had fallen at the very brink of a circular pit, whose extent, of course, I had no means of ascertaining at the moment. Groping about the masonry just below the margin, I succeeded in dislodging a small fragment, and let it fall into the abyss. For many seconds I hearkened to its reverberations as it dashed against the sides of the chasm in its descent; at length there was a sullen plunge into water, succeeded by loud echoes.

As with his deduction that he was, in fact, in a dungeon in the first passage, this quotation shows the narrator using reasoning, dropping the "small fragment" into the "abyss" and listening for it landing, to ascertain his circumstances.  Solving his first problem leads to a much more perilous second one--the pit he cannot see in his cell.