Intercourse by way of trade and traffic between different peoples or states and the citizens or inhabitants there-of, including not only the purchase, sale, and exchange of commodities, but also the ln-strumentallties and agencles hy whlch lt is promoted and the means and appllances by which It ls carried on, and the transporta-tion of persons as well as of goods, both by land and by sea. Brennan v. Titusville, 153
