ABSTRACT
Many of the modern discoveries and inventions already described in these pages have been instances of practical applications of science to the every-day wants of mankind; but the chief interest of the subject the people now enter upon flows mainly from other sources than direct applications of its principles in useful arts, although these applications are already neither few nor unimportant. It has long been known that some substances impart certain colours to flames, and such substances have been long employed to produce colored effects in fire-works, &c. The seeming fixity of the stars is an illusion of the same nature as that which prevents a casual observer from recognizing their apparent diurnal motion, and now the people have also ample evidence that permanence of physical condition, even in the stars, is impossible.
