---------------------+-------+--------+------+-------+-------+-------- No. of the | 1st. | 2d. | 3d. | 4th. | 5th. | 6th. experiment, | | | | | | ---------------------+-------+--------+------+-------+-------+-------- No. of cups in | | | | | | battery, | 14 | 14 | 14 | 7 | 7 | 7 Length of conductors,| | | | | | _w_, _w_, | 400 | 400 | 400 | 400 | 300 | 200 Degrees of motion of | | | | | | galvanometer, |32 & 24|13½ & 4½| 1 & 1|24 & 13|29 & 21|21½ & 15 Size of the copper | | | | | | plates | | | | | | _f_, _g_, _h_, _i_, |5 by 2½|16 by 18|6 by 5|5 by 2½|5 by 2½| 5 by 2½ | ft.| in.| in.| ft.| ft.| ft. ---------------------+-------+--------+------+-------+-------+-------- Showing that electricity crosses the river, and _in quantity in proportion to the size of the plates in the water._ The _distance of the plates on the same side_ of the river _from each other_ also affects the result. Having ascertained the general fact, I was desirous of discovering the best practical distance at which to place my copper plates, and not having the leisure myself, I requested my friend Professor Gale to make the experiments for me. I subjoin his letter and the results. NEW YORK, _November_ 5th, 1844. MY DEAR SIR—I send you, herewith, a copy of a series of results, obtained with four different sized plates, as conductors to be used in crossing rivers. The batteries used were six cups of your smallest size, and one liquid used for the same throughout. I made several other series of experiments, but these I most rely on for uniformity and accuracy. You will see, from inspecting the table, that the distance along the shores should be _three times greater_ than that from shore to shore across the stream; at least, that four times the distance does not give any increase of power. I intend to repeat all these experiments under more favorable circumstances, and will communicate to you the results. Very respectfully, L. D. GALE. Professor S. F. B. MORSE, _Superintendent of Telegraphs_. Series of Experiments on four different sizes of plates, to wit: 1st, 56 square inches; 2d, 28 square inches; 3d, 14 square inches; and 4th, 7 square inches. _Experiment 1st.—Surface of one face of the copper plate, 56 square inches; battery, Morse’s smallest, 6 cups._