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

A few years later the Naval Academy was founded at Annapolis, and a similar course was pursued to provide it with a corps of instructors.

The result was that, if it happened to clear off after a cloudy evening, I frequently arose from my bed at any hour of the night or morning and walked two miles to the observatory to make some observation included in the programme.

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

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

As years passed away I have formed the habit of looking back upon that former self as upon another person, the remembrance of whose emotions has been a solace in adversity and added zest to the enjoyment of prosperity.

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.