For example, as we are authorized by the Constitution and compelled by necessity to build and maintain light-houses on our coast and establish fog-signals, we are bound to make all necessary scientific inquiries in reference to light and its laws, sound and its laws--to do whatever in the way of science is necessary to achieve the best results in lighting our coasts and warning our mariners of danger. So, when we are building iron-clads for our navy or casting guns for our army, we ought to know all that is scientifically possible to be known about the strength of materials and the laws of mechanics which apply to such structures. In short, wherever in exercising any of the necessary functions of the Government scientific inquiry is needed, let us make it, to the fullest extent, and at the public expense. There is another exception to the general rule of leaving science to the voluntary action of the people. Wherever any great popular interest, affecting whole classes, possibly all classes of the community, imperatively need scientific investigation, and private enterprise cannot accomplish it, we may wisely intervene and help where the Constitution gives us authority. For example, in discovering the origin of yellow-fever and the methods of preventing its ravages, the nation should do, for the good of all, what neither the States nor individuals can accomplish. I might perhaps include in a third exception those inquiries which, in consequence of their great magnitude and cost, cannot be successfully made by private individuals. Outside these three classes of inquiries, the Government ought to keep its hands off, and leave scientific experiment and inquiry to the free competition of those bright, intelligent men whose genius leads them into the fields of research. And I suspect, when we read the report of our commissioner to the late Paris Exposition, which shows such astonishing results, so creditable to our country, so honorable to the genius of our people, it will be found, in any final analysis of causes, that the superiority of Americans in that great Exposition resulted mainly from their superior freedom, and the greater competition between mind and mind untrammelled by Government interference; I believe it will be found we are best serving the cause of religion and science, and all those great primary rights which we did not delegate to the Congress or the States, but left the people free to enjoy and maintain them. [Speech on the National Election.]