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 mode of avoiding them is not by praying to the saints, but by insuring personal and municipal cleanliness.  In the twelfth century it was found necessary to pave the streets of Paris, the stench in them was so dreadful At once dysenteries and spotted fever diminished; a sanitary condition approaching that of the Moorish cities of Spain, which had been paved for centuries, was attained.  In that now beautiful metropolis it was forbidden to keep swine, an ordinance resented by the monks of the abbey of St. Anthony, who demanded that the pigs of that saint should go where they chose; the government was obliged to compromise the matter by requiring that bells should be fastened to the animals’ necks.  King Philip, the son of Louis the Fat, had been killed by his horse stumbling over a sow.  Prohibitions were published against throwing slops out of the windows.  In 1870 an eye-witness, the author of this book, at the close of the pontifical rule in Rome, found that, in walking the ordure-defiled streets of that city, it was more necessary to inspect the earth than to contemplate the heavens, in order to preserve personal purity.  Until the beginning of the seventeenth century, the streets of Berlin were never swept.  There was a law that every countryman, who came to market with a cart, should carry back a load of dirt!