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:
Fig. 25.
| Battery alone | 5.20 | inches. | |
| 1 | mile | 3.85 | “ |
| 2 | “ | 2.62 | “ |
| 3 | “ | 1.84 | “ |
| 4 | “ | 1.20 | “ |
| 5 | “ | 1.05 | “ |
| 6 | “ | .92 | “ |
| 7 | “ | .80 | “ |
| 8 | “ | .71 | “ |
| 9 | “ | .64 | “ |
| 10 | “ | .57 | “ |
| 20 | “ | .30 | “ |
| 30 | “ | .20 | “ |
| 40 | “ | .14 | “ |
| 50 | “ | .094 “ | |
During the previous summer, I made the following experiments, upon a line of 33 miles, of number 17 copper wire, with a battery of 50 pairs. In this case, I used a small steelyard, with weights, with which I was enabled to weigh, with a good degree of accuracy, the greater magnetic forces, but not the lesser, yet sufficiently approximating the recent results to confirm the law in question.
| 50 pairs through | 2 | miles | attracted and raised | 9 | ozs. |
| “ | 4 | “ | ““ | 4 | “ |
| “ | 6 | “ | ““ | 3 | “ |
| “ | 8 | “ | ““ | 2½ | “ |
| “ | 10 | “ | ““ | 2¼ | “ |
| “ | 12 | “ | ““ | ⅛ | “ |
| “ | 14 | “ | ““ | ⅛ | “ |
and each successive addition of two miles, up to 33, still gave an attractive and lifting power of one-eighth of an ounce.
Curve from these Results.