PYRAMIDS OF DJIZA. 191 
precaution whereby the quality of the air below ^?y ^" 
may be proved, and those fatal effects prevented ' ■ s>' * 
which often attend an improvident descent into 
wells, and subterraneous chambers of every 
description. Many hands, too, would be re- 
quired above, to manage and sustain the ropes 
by which any adventurer, during the experiment, 
must remain suspended. The greatest danger 
to be apprehended would consist in the hazard 
of an exposure to mephitic air; but due precau- 
tion, in a careful attention to the tapers lowered 
first, might obviate this. We threw down some 
stones, and observed that they rested at about 
the depth which Greaves has mentioned; but 
being at length provided with a stone nearly as 
large as the mouth of the well, and about fifty 
pounds in weight, we threw this down, and 
observed that, after striking upon the spot 
where the other stones rested, after a length of 
time which must have equalled some seconds, it 
produced a loud and distinct report, seeming 
to come from a spacious subterraneous apart- 
ment ; and it was accompanied by a splashing 
noise, as if the stone had been broken into pieces, 
and had fallen into a reservoir of water at a very 
considerable depth. Thus does experience 
always tend to confirm the accounts left us by 
