When James Watt retired from business towards the close of his useful and admirable life, he spoke to his friends of occupying himself with “ingenious trifles,” and of turning “some of his idle thoughts” upon the invention of an arithmetical machine and a machine for copying sculpture. These and other useful works occupied his attention for many years.

It was the same with myself. I had good health (which Watt had not) and abundant energy. When I retired from business I was only forty-eight years old, which may be considered the prime of life. But I had plenty of hobbies, perhaps the chief of which was Astronomy. No sooner had I settled at Hammerfield than I had my telescopes brought out and mounted. The fine clear skies with which we were favoured, furnished me with abundant opportunities for the use of my instruments. I began again my investigations on the Sun and the Moon, and made some original discoveries, of which more anon.

Early in the year 1858 I received a pressing invitation from the Council of the Edinburgh Philosophical Society to give a lecture before their members on the Structure of the Lunar Surface. As the subject was a favourite one with me, and as I had continued my investigations and increased my store of drawings since I had last appeared before an Edinburgh audience, I cheerfully complied with their request.