My first undertaking in the way of scientific experiment was in the field of economics and psychology.

I had not yet gotten into the world of light. But I felt as one who, standing outside, could knock against the wall and hear an answering knock from within.

Until I was four years old I lived in the house of my paternal grandfather, about two miles from the pretty little village of Wallace, at the mouth of the river of that name.

Aerial flight is one of that class of problems with which man will never be able to cope. . . . The example of the bird does not prove that man can fly. Imagine the proud possessor of the aeroplane darting through the air at a speed of several hundred feet per second. It is the speed alone that sustains him. How is he ever going to stop?

Construction of an aerial vehicle which can carry even a single man . . . requires the discovery of some new metal or force. Even with such a discovery, we could not expect one to do more than carry its owner.

We are probably nearing the limit of all we can know about astronomy.

My father was the most rational and the most dispassionate of men.