1660s, cast iron, from iron (n.) + cast (adj.) "made by melting and being left to harden in a mold" (1530s), past-participle adjective from cast (v.) in its sense "to throw something (in a particular way)," c. 1300, especially "form metal into a shape by pouring it molten" (1510s). From 1690s as an adjective, "made of cast-iron;" figurative sense of "inflexible, unyielding" is from 1830.
"philanderer, womanizer," from the legendary dissolute Spanish nobleman whose rakish exploits formed the stuff of popular tales in Spain from early 17c., dramatized by Gabriel Tellez in "Convivado de Piedra." Adapted into French and Italian before 1700; Used attributively in English for "ladies' man, womanizer" from the time of Byron's popular poem about him (1819). Compare Casanova, Lothario, philander, all originally character names.
motto of the United States, being one nation formed by uniting several states, 1782, Latin, from e "out of" (see ex-); ablative plural of plus "more" (see plus (n.)); neuter of unus "one" (from PIE root *oi-no- "one, unique"). Not found in classical Latin, though a variant of the phrase appears in Virgil (color est e pluribus unum); the full phrase was the motto of the popular Gentleman's Magazine from 1731 into the 1750s.
Previous to 1883 the methods of measuring time in the United States were so varied and so numerous as to be ludicrous. There were 50 different standards used in the United States, and on one road between New York and Boston, whose actual difference is 12 minutes, there were three distinct standards of time. Even small towns had two different standards one known as "town" or local time and the other "railroad" time.
... At noon on November 18, 1883, there was a general resetting of watches and clocks all over the United States and Canada, and the four great time zones, one hour apart, into which the country was divided came into being. So smoothly did the plan work that the general readjustment was accomplished without great difficulty and it has worked satisfactorily ever since. [Railroad Trainman, September 1909]