Isotropy and anisotropy: When a material is attacked by a liquid or vapor etchant, it is removed isotropically (uniformly in. all directions) or anisotropic etching (uniformity in vertical direction).
Some Questions Do Remain: 1  If the Earth was flat, we could travel to the place where the Earth and sky met. But we canât. 2  If the Earth was flat, we could reach the place where we could reach out and touch the Sun. But we canât. 3  If the Earth was flat, we could fall off the horizon. But we donâ 4 t. If the Earth was flat, it would simply fall.
But now, drawing back to the edge of the table, gradually lower your eye (thus bringing yourself more and more into the condition of the inhabitants of Flatland), and you will find the penny becoming more and more oval to your view, and at last when you have placed your eye exactly on the edge of the table (so that you are, as it were, actually a Flatlander) the penny will then have ceased to appear oval at all, and will have become, so far as you can see, a straight line.