ART. XVI. _Experiments made with one hundred pairs of Grove’s battery, passing through one hundred and sixty miles of insulated wire_; in a letter from Prof. S. F. B. Morse, to the Editors, dated New York, Sept. 4th, 1843. Dear Sirs—On the 8th of August, having completed my preparations of 160 miles of copper wire for the Electro Magnetic Telegraph, which I am constructing for the government, I invited several scientific friends to witness some experiments in verification of the law of Lenz, of the action of galvanic electricity through wires of great lengths. I put in action a cup battery of one hundred pairs, which I had constructed, based on the excellent plan of Prof. Grove, but with some modifications of my own, economising the platinum. The wire was reeled upon eighty reels, containing two miles upon each reel, so that any length, from two to one hundred and sixty miles, could be made at pleasure to constitute the circuit. My first trial of the battery was through the entire length of 160 miles, making of course a circuit of 80 miles, and the magnetism induced in my electro magnet,[10] which formed a part of the circuit, was sufficient to move with great strength, my telegraphic lever. Even forty-eight cups produced action in the lever, but not so promptly or surely. We then commenced a series of experiments upon decomposition, at various distances. The battery alone (100 pairs) gave, in the measuring gauge in one minute, 5.20 inches of gas. When four miles of wire were interposed, the result was 1.20 inches; ten miles of wire, .57; 20 miles, .30 inches; 50 miles, .094. The results obtained from a battery of 100 pairs are projected in the following curve: [10] In Prof. Daniel’s, Introduction to the Study of Chemical Philosophy, 2d edition, 1843, there are these facts to be noticed. In the preface, there are these words: “It only remains for me now, to acknowledge my obligations to my friends and colleagues, _Professor Wheatstone_ and Dr. Todd, for their great kindness in undergoing the disagreeable labour of revising and correcting the proof sheets. They have thereby prevented many errors which would have otherwise deformed the work.” No statement then of Prof. Daniel’s, particularly in that part of his work which related especially to Wheatstone’s Telegraph, would be allowed to pass unnoticed by Mr. Wheatstone and we are authorized in considering any such statement as having his sanction.