Usage examples (10)

• I put one on a piece of ferrotype plate, and that gave really the best result I ever got.
• I tried putting in a large number of these tubes, all in quantity, on the bottom of a ferrotype plate, but with no advantage.
• The most distinct articulate speech was obtained from an ordinary ferrotype telephone plate, secured at the edges, and one of the glass tubes you see here attached to it.
• My method is to mount not more than half a dozen at once, placing them face down, one on top of the other, on a glass or ferrotype plate, blotting off the surface water...