How far we traversed the tunnel in this manner I do not know, but presently we came to an obstruction which blocked our further progress. It seemed more like a partition than a sudden ending of the cave, for it was constructed not of the material of the cliff, but of something which felt like very hard wood.
Silently I groped over its surface with my hands, and presently was rewarded by the feel of the button which as commonly denotes a door on Mars as does a door knob on Earth.
Gently pressing it, I had the satisfaction of feeling the door slowly give before me, and in another instant we were looking into a dimly lighted apartment, which, so far as we could see, was unoccupied.
