The "North British Mail" says, there are at present 100 vessels in course of construction on the Clyde, and of these only 6 are timber-built, all the rest being built of iron. It is also notable that these iron vessels consist both of steam and sailing vesssls, though the former class preponderates. The tonnage of the ships now in construction on the Clyde amounts to upwards of 60,000 tons. The engines of the steam part of this great fleet have an aggregate of more than 14,000 horse-power. The probable value of the whole, though necessarily inexact, cannot be much short of 2,000.000 sterling Yet, in a few months, this enormous amount of shipping will be off the stocks, and its place supplied by a new production, equally valuable. The number of workmen employed in building the vessels and making the machinery is about 15,000. The number of hands employed in raising the raw materials from the basin ot the Clyde within a circuit of 20 or 30 miles, lor these and similar great works, is still more immense. Another most gratifying feature of the ship-building trade of the Clyde is, that the employers in nearly all the establishments were workingmea themselves within the last thirty years. Most of them had attained the period of middle life before they turned their attention to iron boat-building at all. The men are not only the architects of their own fortunes, but the creators of a new branch of industry.