The exterior of an apparatus (next to the interior) ought to receive careful attention too. A visitor in the establishment looks admiringly on a brightly shining apparatus, which raises the value of the product in his eyes; it gives him confidence, and this is quite natural. If we see our meals cooked in dirty dishes, our appetite is spoiled. Therefore keep the exterior as well in order as the interior. Keep the entire apparatus brightly painted, light metal parts polished, and the whole always ready for inspection by any one. If the apparatus is of iron, coat it nicely with oil paint.