Mackinac Bridge steel grates are for sale. Here's how you can get one
Mackinac Bridge grates for sale are approximately 5½ feet by 38 feet and 5 inches, with each weighing about 2 tons.
Nature4y
A well designed diffraction grating is key for innovation
in 1974 Hitachi invented its landmark third machine, capable of ruling variably spaced, curved grooves on a concave grating. The machine allows the user to control conditions for correcting ...