The principles adopted by the ancients in weaving and spinning by hand are those still in force; but so great was the advance of inventions from hand-operated mechanisms to machines in these and other arts, and especially in steam, in the last half of the eighteenth century, that it has been claimed that the age of machine production or invention then for the first time really began. When the humble lift became the completed elevator of to-day, the “sky-scraper” buildings appeared; but these buildings waited upon the invention of their steel skeletons, and the steel was the child of the Bessemer process. The harp with which David stirred the dead soul of Saul was the prototype of the sweet clavichord, the romantic virginal, the tinkling harpsichord, and the grand piano. The thrumming of the chords by the fingers was succeeded by the striking keys; and the more perfect rendition of tones awaited the application of new discoveries in the realm of musical sounds. The keys and the levers in the art of musical instruments were transferred to the art of printing, and are found to-day striking a more homely music on the type-writer and on those other and more wonderful printing instruments that mould, and set, and distribute the type. But these results of later days did not reach their perfected operations and forms until many other arts had been discovered and developed, by which to treat and improve the wood, and the wire, and all the other materials of which those early instruments were composed, and by which the underlying principles of their operations became known. Admitting that man possesses the faculty of invention, what are the motives that induce its exercise? Why so prolific in inventions now? And will they continue to increase in number and importance, or decrease? An interesting treatise of bulky dimensions might be written in answer to these queries, and the answers might not then be wholly satisfactory. Space permits the submission of but a few observations and suggestions on these points:---- _Necessity_ is still the mother of inventions, but not of all of them. The pressing needs of man in fighting nakedness and hunger, wild beasts and storms, may have driven him to the production of most of his early contrivances; but as time went on and his wants of every kind multiplied, other factors than mere necessity entered into the problem, and now it is required to account for the multiplicity of inventions under the general head of _Wants_. To-day it is the want of the luxuries, as well as of the necessities of life, the want of riches, distinction, power, and place, the wants of philanthropy and the wants of selfishness, and that restless, inherent, unsatisfied, indescribable want which is ever pushing man onward on the road of progress, that must be regarded as the springs of invention.