Citations:warn

general

 * 1843 — Charles Dickens. A Christmas Carol.
 * "That is no light part of my penance," pursued the Ghost. "I am here to-night to warn you, that you have yet a chance and hope of escaping my fate. A chance and hope of my procuring, Ebenezer."

clock

 * 1896, Frederick James Britten, The Watch & Clock Makers' Handbook, Dictionary and Guide, page 88:
 * [...] also to see that they are well free of the boss of the gathering pallet — not only when it is in position resting on the rack pin, but also when it has moved into the position that it would be in when the clock has warned. If the boss of the pallet is [...]
 * 1910, The Sketch: A Journal of Art and Actuality, volume 71, page 252:
 * Then the clock warned, and the woman started up from her seat. The man thought the clock was about to strike, and he began to tear frantically at the bandage.

warn in: to swear in

 * 1874, Reports from Commissioners, appendix XVI to the Fourth Report, page 118-119:
 * 7. To constitute a provincial grand lodge there must be not fewer members present than the number which shall have been agreed upon at a warned-in meeting of the chapter, as necessary to constitute a chapter, which number, however, may be altered (at a warned-in chapter only), as circumstances may render necessary.