he spiral
spring, and various escapements in succession were devised, such as the
anchor, the dead-beat, the duplex, the remontoir. Provisions for the
variation of temperature were introduced. It was brought to perfection
eventually by Harrison and Arnold, in their hands becoming an accurate
measure of the flight of time. To the invention of the chronometer
must be added that of the reflecting sextant by Godfrey. This permitted
astronomical observations to be made, notwithstanding the motion of a
ship.

Improvements in ocean navigation are exercising a powerful influence on
the distribution of mankind. They are increasing the amount and altering
the character of colonization.

DOMESTIC IMPROVEMENT. But not alone have these great discoveries and
inventions, the offspring of scientific investigation, changed the
lot of the human race; very many minor ones, perhaps individually
insignificant, have in their aggregate accomplished surprising effects.
The commencing cultivation of science in the fourteenth century gave
a wonderful stimulus to inventive talent, directed mainly to useful
practical results; and this, subsequently, was greatly encouraged by the
system of patents, which secure to the originator a reasonable portion
of the benefits of his skill. It is sufficient to refer in the most
cursory manner to a few of these improvements; we appreciate at once how
much they have done. The introduction of the saw-mill gave wooden floors
to houses, banishing those of gypsum, tile, or stone; improvements
cheapening the manufacture of glass gave windows, making possible the
warming of apartments. However, it was not until the sixteenth century
that glazing could be well done. The cutting of glass by the diamond
was then introduced. The addition of chimneys purified the atmosphere
of dwellings, smoky and sooty as the huts of savages; it gave that
indescribable blessing of northern homes--a cheerful fireside. Hitherto
a hole in the roof for the escape of the smoke, a pit in the midst of
the floor to contain the fuel, and to be covered with a lid when the
curfew-bell sounded or night came, such had been the cheerless and
inadequate means of warming.

MUNICIPAL IMPROVEMENTS. Though not without a bitter resistance on
the part of the clergy, men began to think that pestilences are not
punishments inflicted by God on society for its religious shortcomings,
but the physical consequences of filth and wretchedness; that the proper
mod