Natural Science treats of motion and force. Many of its teachings remain as part of an educated man's permanent equipment in life.
Such are:
(a) The harder you shove a bicycle the faster it will go. This is because of natural science.
(b) If you fall from a high tower, you fall quicker and quicker and quicker; a judicious selection of a tower will ensure any rate of speed.(c) If you put your thumb in between two cogs it will go on and on, until the wheels are arrested, by your suspenders. This is machinery.
(d) Electricity is of two kinds, positive and negative. The difference is, I presume, that one kind comes a little more expensive, but is more durable; the other is a cheaper thing, but the moths get into it.