My father followed, during most of his life, the precarious occupation of a country school teacher.

One of the most beautiful hypotheses ever propounded in physics is ... the Dynamical Theory of Gases

The beginning of 1856 found me teaching in the family of a planter named Bryan, residing in Prince George County, Md., some fifteen or twenty miles from Washington.

Whenever a total eclipse of the sun was visible in an accessible region parties were sent out to observe it.

Aerial flight is one of that class of problems with which man will never be able to cope.

When about fifteen I once made a great scandal by taking out my knife in prayer meeting and assaulting a young man who, while I was kneeling down during the prayer, stood above me and squeezed my neck.

Ten decimal places of π are sufficient to give the circumference of the earth to a fraction of an inch, and thirty decimal places would give the circumference of the visible universe to a quantity imperceptible to the most powerful microscope.