Who was Galileo?

A most eminent astronomer and mathematician, born at Florence, in Italy.  His inventions and discoveries in Astronomy, Geometry, and Mechanics, contributed much to the advancement of those sciences.  He died in 1642.

     Astronomer, one versed in Astronomy.

     Mathematician, one versed in Mathematics; a science which
     treats of magnitude and number.

What is Astronomy?[12]

That science which teaches the knowledge of the heavenly bodies, with the nature and causes of their various phenomena.

[Footnote 12:  See Chapter xviii.]

What is Geometry?

An ancient, perfect, and beautiful science, which treats of the relations and properties of lines, surfaces, and solids.

What is meant by Mechanics?

The science which investigates the laws of forces and powers, and their action on bodies, either directly or by machinery.  When the term mechanic is applied to a person, it means one skilled in mechanics, accustomed to manual labor.

     Investigate, to search, to inquire into.

     Manual, performed by the hand.

What is a Microscope?

An optical instrument, by means of which very minute objects are represented exceedingly large, and viewed very distinctly according to the laws of refraction or reflection.  Nothing certain is known respecting the inventor of microscopes, or the exact time of their invention, but that they were first used in Germany, about 1621.

     Minute, small, diminutive.

     Refraction, a change in the direction of a ray of light,
     when it passes through transparent substances of different
     densities.

     Reflection, a turning back of a ray of light after
     striking upon any surface.

What is the Steam Engine?

A machine that derives its moving power from the force of the steam produced from boiling water, which is very great, especially when, as in the steam engine, it is confined within a limited compass:  this useful machine is one of the most valuable presents that the arts of life have received from the philosopher, and is of the greatest importance in working mines; supplying cities with water; in working metals; in many mechanical arts; and in navigation.  By the aid of steam, vessels are propelled with greater swiftness than those which are wholly dependent on the winds and tides; and thus trade is facilitated, and we are enabled to communicate with distant lands in a much shorter space of time than was formerly consumed.  On land, railroads are constructed, on which steam carriages run with astonishing rapidity, so that a journey which by coach and horses formerly required two or more days, may now be performed in four or five hours.

     Mechanical, belonging to Mechanics.