Among the other things which I sent to Innes was over five hundred miles of double, insulated wire of a very fine gauge.  I had it packed on a special reel at his suggestion, as it was his idea that he could fasten one end here before he left and by paying it out through the end of the prospector lay a telegraph line between the outer and inner worlds.  In my letter I told him to be sure to mark the terminus of the line very plainly with a high cairn, in case I was not able to reach him before he set out, so that I might easily find and communicate with him should he be so fortunate as to reach Pellucidar.

I received several letters from him after I returned to America—­in fact he took advantage of every northward-passing caravan to drop me word of some sort.  His last letter was written the day before he intended to depart.  Here it is.

MY DEAR FRIEND: 

Tomorrow I shall set out in quest of Pellucidar and Dian.  That is if the Arabs don’t get me.  They have been very nasty of late.  I don’t know the cause, but on two occasions they have threatened my life.  One, more friendly than the rest, told me today that they intended attacking me tonight.  It would be unfortunate should anything of that sort happen now that I am so nearly ready to depart.

However, maybe I will be as well off, for the nearer the hour approaches, the slenderer my chances for success appear.

Here is the friendly Arab who is to take this letter north for me, so good-bye, and God bless you for your kindness to me.

The Arab tells me to hurry, for he sees a cloud of sand to the south—­he thinks it is the party coming to murder me, and he doesn’t want to be found with me.  So good-bye again.

Yours,

David Innes.

A year later found me at the end of the railroad once more, headed for the spot where I had left Innes.  My first disappointment was when I discovered that my old guide had died within a few weeks of my return, nor could I find any member of my former party who could lead me to the same spot.

For months I searched that scorching land, interviewing countless desert sheiks in the hope that at last I might find one who had heard of Innes and his wonderful iron mole.  Constantly my eyes scanned the blinding waste of sand for the ricky cairn beneath which I was to find the wires leading to Pellucidar—­but always was I unsuccessful.

And always do these awful questions harass me when I think of David Innes and his strange adventures.

Did the Arabs murder him, after all, just on the eve of his departure?  Or, did he again turn the nose of his iron monster toward the inner world?  Did he reach it, or lies he somewhere buried in the heart of the great crust?  And if he did come again to Pellucidar was it to break through into the bottom of one of her great island seas, or among some savage race far, far from the land of his heart’s desire?