Tough Glass

Blow glass into a hollow sphere, kick it about like a football. Mould glass into a tumbler, heat it to the point where pieces of paper in the tumblers are charred, plunge it into cold water. These are tests which were withstood by recently discovered "unbreakable glass."

The inventor is Dr. Horak, a Czech engineer. He does not claim to have found the secret of unbreakable glass. He does claim his glass is tougher than any yet known.