engaged by some experiments on an air-pump, which I saw employed by a gentleman whom we were in the habit of visiting.
The ignorance of the early philosophers on these and several other points served to decrease their credit with me: but I could not entirely throw them aside, before some other system should occupy their place in my mind.
When I was about fifteen years old, we had retired to our house near Belrive, when we witnessed a most violent and terrible thunder-storm. It advanced from behind the mountains of Jura; and the thunder burst at once with frightful loudness from various quarters of the heavens. I remained, while the storm lasted, watching its progress with curiosity and delight. As I stood at the door, on a sudden I beheld a stream of fire issue from an old and beautiful oak,
