It was long before this invention was perfected and brought into general use.

It was not the production of one man, but of several generations of mechanical inventors.

A perfected invention does not burst forth from the brain like a poetic thought or a fine resolve.

It has to be initiated, laboured over, and pursued in the face of disappointments, difficulties, and discouragements.
Sometimes the idea is born in one generation, followed out in the next, and perhaps perfected in the third.

In an age of progress, one invention merely paves the way for another.