This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it.

This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it.

This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it.

Machinery, though it has lightened other branches of labour and cheapened production, has not helped us much here.

This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it. This work is in the "public domain in the United States of America, and possibly other nations.