Etymology
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thread (n.)

Old English þræd "fine cord, especially when twisted" (related to þrawan "to twist"), from Proto-Germanic *thredu- "twisted yarn" (source also of Old Saxon thrad, Old Frisian thred, Middle Dutch draet, Dutch draad, Old High German drat, German Draht, Old Norse þraðr), literally "twisted," from suffixed form of PIE root *tere- (1) "to rub, turn." Meaning "spiral ridge of a screw" is from 1670s. Threads, slang for "clothes" is 1926, American English.

The silk line, as spun by the worm, is about the 5000th part of an inch thick; but a spider's line is perhaps six times finer, or only the 30,000th part of an inch in diameter, insomuch, that a single pound of this attenuated substance might be sufficient to encompass our globe. [John Leslie, "Elements of Natural Philosophy," Edinburgh, 1823]
Nuts and bolts you know as little things that put big things together. Actually, our whole industrial civilization hangs by a thread—a screw thread. [Popular Science, March 1949]
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clue (n.)

"anything that guides or directs in an intricate case," 1590s, a special use of a revised spelling of clew "a ball of thread or yarn" (q.v.). The word, which is native Germanic, in Middle English was clewe, also cleue; some words borrowed from Old French in -ue, -eu also were spelled -ew in Middle English, such as blew, imbew, but these later were reformed to -ue, and this process was extended to native words (hue, true, clue) which had ended in a vowel and -w. The spelling clue is first attested mid-15c.

The sense shift is originally in reference to the clew of thread given by Ariadne to Theseus to use as a guide out of the Labyrinth in Greek mythology. The purely figurative sense of "that which points the way," without regard to labyrinths, is from 1620s. As something which a bewildered person does not have, by 1948.

Thus hardy Theseus, with intrepid Feet,
Travers'd the dang'rous Labyrinth of Crete;
But still the wandring Passes forc'd his Stay,
Till Ariadne's Clue unwinds the Way
[Gay, "Trivia"]

The board game (originally Cluedo) was launched in 1949 in Britain.

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marine (n.)

late 14c., "seacoast;" see marine (adj.). Meaning "collective shipping of a country" is from 1660s. Meaning "soldier who serves on a ship" is from 1670s, a separate borrowing from French marine, from the French adjective. Phrase tell that to the marines (1805) originally was the first half of a retort expressing disbelief in some statement made or story told:

"Upon my soul, sir," answered the lieutenant, "when I thought she scorned my passion, I wept like a child."
"Belay there!" cried the captain; "you may tell that to the marines, but I'll be d----d if the sailors will believe it." ["John Moore," "The Post-Captain; or, the Wooden Walls Well Manned," 1805]

The book, a rollicking sea romance/adventure novel, was popular in its day and the remark is a recurring punch line in it (repeated at least four times). It was written by naval veteran John Davis (1774-1854) but published under the pseudonym "John Moore." Walsh records that, among sailors, marines are "a proverbially gullible lot, capable of swallowing any yarn, in size varying from a yawl-boat to a full-rigged frigate."

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