Here, then, is at once a notable difference between a ray of ordinary light and one that emerges from a rhomb of Iceland spar; for, in the case of rays of ordinary light, we have seen that the second rhomb would divide each ray into two, whereas it is incapable (in the position of crystals under consideration) of dividing either the ordinary or the extraordinary ray which emerges from the first rhomb.
— from Discoveries and Inventions of the Nineteenth Century by Robert Routledge

Under cover of darkness every available car had been loaded with stores, guns, whatever could be saved.
— from The Japan-Russia War: An Illustrated History of the War in the Far East by Sydney Tyler

V OLTAIRE , ΠUVRES C OMPLETES D E .
— from Notes and Queries, Vol. V, Number 123, March 6, 1852 A Medium of Inter-communication for Literary Men, Artists, Antiquaries, Genealogists, etc. by Various

Out you go, under cover of darkness, equipped with flashlights and flash bulbs.
— from Blue Ridge Country by Jean Thomas

Every effort made to send these men to the rear as prisoners under charge of details ended in a report from the commander of the detail that the negroes had "escaped."
— from The History of the Confederate War, Its Causes and Its Conduct, Volume 2 (of 2) A Narrative and Critical History by George Cary Eggleston

In this point the Œcumenical Council followed the [Pg 96] example of Hadrian ( a.d. 117-138), the adopted father of Antoninus Pius, who also commanded the jurist Salvius Julianus to draw up the Edictum Perpetuum , or fixed code, and the Responsa Prudentium , which before his time formed an unwritten corps of doctrine embodying legal decisions and precedents.
— from The Jew, The Gypsy and El Islam by Burton, Richard Francis, Sir

Palmer's Origines liturgicae (3d ed., Oxford, 1839; 4th ed., London, 1845) has also been of service; while new light is thrown on social conditions in Elizabeth's reign by the unique collection of documents edited for the Early English Text Society by Furnivall, Child-Marriages, Divorces, and Ratifications (London, 1897).]
— from A History of Matrimonial Institutions, Vol. 1 of 3 by George Elliott Howard

224 Through the mud and under cover of darkness every bit of barbed wire, every board, every ounce of food, must go up to the moles in the ditch.
— from My Year of the Great War by Frederick Palmer

Having caught them here General Broadwood made a brisk fight of it, but the Boers under cover of darkness evaded pursuit.
— from South Africa and the Transvaal War, Vol. 6 (of 8) From the Occupation of Pretoria to Mr. Kruger's Departure from South Africa, with a Summarised Account of the Guerilla War to March 1901 by Louis Creswicke