The second letter is as follows:-- "I have no time to answer your objection against 'knockers'; I have a large treatise collected on that head, and what Mr. Derham says is nothing to the purpose. If sounds of voices, whispers, blasts, working, or pumping, can be carried on a mile underground, they should always be heard in the same place, and under the same advantages, and not once in a month, a year, or two years. Just before the discovery of ore last week, three men together in our work at "Llwyn Llwyd" were ear-witnesses of "knockers," pumping, driving a wheelbarrow, etc.; but there is no pump in the work, nor any mine within less than a mile of it, in which there are pumps constantly going. If they were these pumps that they heard, why were they never heard but that once in the space of a year? And why are they not now heard? But the pumps make so little noise that they cannot be heard in the other end of "Esgair y Mwyn" mine when they are at work. We have a dumb and deaf tailor in the neighbourhood who has a particular language of his own by signs, and by practice I can understand him and make him understand me pretty well, and I am sure I could make him learn to write, and be understood by letters very soon, for he can distinguish men already by the letters of their names. Now letters are marks to convey ideas, just after the same manner as the motion of fingers, hands, eyes, etc. If this man had really seen ore in the bottom of a sink of water in a mine and wanted to tell me how to come at it, he would take two sticks like a pump, and would make the motions of a pumper at the very sink where he knew the ore was, and would make the motions of driving a wheelbarrow. And what I should infer from thence would be that I ought to take out the water and sink or drive in the place, and wheel the stuff out. By parity of reasoning, the language of "knockers," by imitating the sound of pumping, wheeling, etc., signifies that we should take out the water and drive there. This is the opinion of all old miners, who pretend to understand the language of the "knockers." Our agent and manager, upon the strength of this notice, goes on and expect great things. You, and everybody that is not convinced of the being of "knockers," will laugh at these things, for they sound like dreams; so does every dark science. Can you make any illiterate man believe that it is possible to know the distance of two places by looking at them? Human knowledge is but of small extent, its bounds are within our view, we see nothing beyond these; the great universal creation contains powers, etc., that we cannot so much as guess at. May there not exist beings, and vast powers infinitely smaller than the particles of air, to whom air is as hard a body as the diamond is to us? Why not? There is neither great nor small, but by comparison. Our "knockers" are some of these powers, the guardians of mines.