R. Armstrong, directs the attention of the public, through the London Mechanics Magazine of April 10th, to the unreliable character of the above-named fastenings for ships. He mentions the articles which appeared in the Scientific American (Vol. X) on this subject. In the repairing of vessels bolted with yellow metal, he has observed that in every instance where it has been in a vessel for five years, it had lost its ductilitv, and was, therefore, totally unfit for ship bolts. At various times he has personally called the attention of Lloyds' surveyors to this, but they have still classed vessels "A 1, 13 years,'' while he can safely assert, from experience, that four years are amply sufficiently to destroy the ductility of their bolts. He gives the British Admiralty credit for standing above the mercantile marine on this question —nothing but pure copper bolting being employed in the navy. He hopes the public will now demand that something positive be done to prevent the use of such ship fastenings. We hope that neither bolts nor sheathing of yellow metal are now employed by our shipbuilders—this metal being totally unfit for us in shipbuilding.