SELF-ACTING ENGINES, INCLUDING THE NASMYTH STEAM HAMMER 295 GREAT FACTS. THE PROGRESS OF INVENTION. The inventive faculty of man tends more directly than any other intellectual power he possesses to raise him in the scale of creation above the brutes. Nearly every advance he makes beyond the exercise of his natural instincts is caused by invention--by that power of the mind which combines known properties in different ways to obtain new results. When an Indian clothes himself with the skins of animals, and when he collects the dried leaves of the forest for his bed, he is either an original inventor, or he is profiting by the inventions of others. Those simple contrivances--the first steps in the progress of invention--are succeeded by the more labored efforts of inventive genius, such as contriving means of shelter from rain, or from the heat of the sun, when caves cannot be found to creep into, or the overhanging foliage fails to afford sufficient covering. The construction of places of shelter is an imitation of the protection formed by Nature; and the rudest hut and the most magnificent palaces have their prototypes in caverns and in the interlacing branches of trees. Nature also supplies knowledge of the means by which inventors are enabled to work. The savage who seizes hold of a broken bough is in possession of the _lever_, the uses of which he learns by the facility it affords in moving other objects. He ascends to the top of a precipice by walking up the sloping hill behind, and he thus becomes practically acquainted with the principle of the _inclined plane_. The elements of all the mechanical powers are then at his command, to be applied by degrees in administering to his wants, as his inventive faculties, guided by observation and experience, suggest. An accidental kick against a loose stone shows the action of propulsive force; and the stone that he has struck with his foot, he learns to throw with his hand. The bending of the boughs of trees to and fro by the wind teaches the action of springs; and in the course of time the bow is bent by a strip of hide, and the relaxation of the spring, after farther bending, propels the arrow. Observation and imitation thus lead to invention, and every new invention forms the foundation of further progress. It has been so with every invention at present known, and must so continue to the end of time:--"There is nothing new under the sun." Gas lighting, Steam locomotion, and the Electric Telegraph have each sprung from some source "old as the hills," though so modified by gradually progressive changes, that the giant we now see bears no resemblance to the infant of ages past.