A calculation has been made by which it appears that, of overland and submarine telegraphs, there are completed and in progress of construction at the present time, the following lengths: United States 33,000 miles overland; South America, 1,500 miles, overland ; Europe, 37,900 miles, overland; India, 5,000 miles, overland. Submarine, Europe and America, 900 miles. Total, 78,350 miles. This aggregate will be increased 1,700 miles by the completion of the Atlantic Telegraph. Of the European and Indian telegraphs, not more than from six to seven thousand miles of the lines commenced are finished, yet the next si" months will probably see them all in operation.