For the father, the mother of invention was always the same.

It was a development of the invention he had made in 1892.

"But they didn't yet have the history of invention or a need for those things."

Your great country is leading the way in the important work of invention.

For six years, he worked on one of his own inventions.

In fact, some of their inventions are still used today.

There is really no end to the march of invention.

"Now what sort of invention would you say that might be?"

"And the new system is one of your own invention?"

After playing through these parts remember to work out other similar ideas of your own invention.