Benjamin C. B. Tilghman, of Philadelphia, once went into the lighthouse at Cape May, and, observing that the window glass was translucent rather than transparent, asked the keeper why he put ground glass in the windows. "We do not," said the keeper. "We put in the clear glass, and the wind blows the sand against it and roughens the outer surface like ground glass." The answer was to him like the falling apple to Newton. He put on his thinking cap and went out. It was better than the cap of Fortunatus to him. He thought, "If nature does this, why cannot I make a fiercer blast, let sand trickle into it, and so hurl a million little hammers at the glass, and grind it more swiftly than we do on stones with a stream of wet sand added?" He tried jets of steam and of air with sand, and found that he could roughen a pane of glass almost instantly. By coating a part of the glass with hot beeswax, applied with a brush, through a stencil, or covering it with paper cut into any desired figures, he could engrave the most delicate and intricate patterns as readily as if plain. Glass is often made all white, except a very thin coating of brilliant colored glass on one side. This he could cut through, leaving letters of brilliant color and the general surface white, or _vice versa_. Seal cutting is a very delicate and difficult art, old as the Pharaohs. Protect the surface that is to be left, and the sand blast will cut out the required design neatly and swiftly. There is no known substance, not even corundum, hard enough to resist the swift impact of myriads of little stones. It will cut more granite into shape in an hour than a man can in a day. Surely no one will be sorry to learn that General Tilghman sold part of his patents, taken out in October, 1870, for $400,000, and receives the untold benefits of the rest to this day. So much for thinking. Nature gives thousands of hints. Some can take them; some can only take the other thing. The hints are greatly preferred by nature and man. CREATIONS NOW IN PROGRESS The forces of creation are yet in full play. Who can direct them? Rewards greater than Tilghman's await the thinker. We are permitted not only to think God's thoughts after him, but to do his works. "Greater works than these that I do shall he do who believeth on me," says the Greatest Worker. Great profit incites to do the work noted below. Carbon as charcoal is worth about six cents a bushel; as plumbago, for lead pencils or for the bicycle chain, it is worth more; as diamond it has been sold for $500,000 for less than an ounce, and that was regarded as less than half its value. Such a stone is so valuable that $15,000 has been spent in grinding and polishing its surface. The glazier pays $5.00 for a bit of carbon so small that it would take about ten thousand of them to make an ounce.