MESSRS. EDITORS—The SCIENTIFIC AMERICAN of March 13th contains an article under the above caption. I entirely differ with its writer as to the practicability of working three thousand miles of the proposed submarine cable with a battery totally inadequate to fuse the conducting medium, and I base my belief upon actual experiments made, not upon cable in coils, nor submerged ; but upon parallel lines of subterranean cable. Rest assured the enterprising projectors of this immense undertaking have not entered into it without adequate research, and despite of groundless alarms, you and I will probably live to see numerous channels of thought traversing the broad Atlantic. W. H. C