1893, “Time and Its Landmarks”, in J. C. Thomas, editor,Manual of Useful Information[…] (The Working Teachers’ Library; V), Chicago, Ill.: The Werner Company,→OCLC,page41:
The American Society of Civil Engineers recently announced a meeting of the society to occur at their house in New York at 20.30 o'clock, thus springing thetwenty-four hour clock system upon those who wished to attend, and causing some inquiries and explanations as to the time intended. Commodore Melville, who was to be present, was one of those who had to inquire and to be informed that 8.30 P. M. was intended.
The sidereal clock of the astronomerdoes run to a regular motion; but our24-hour clocksdo not, as we shall see later.
1942, Harold E. Baughman, “Civil Air Communications: Reprinted from Manual of Operations: Chapter B—Communications Section”, inBaughman’s Aviation Dictionary and Reference Guide[…], 2nd edition, Los Angeles, Calif.:Aero Publishers,→OCLC,paragraphs B5.1072–B5.10720,page363:
Time shall be stated in exactly four figures utilizing the twenty-four clock basis.[…] Midnight is 0000, never 2400. The last hour of thetwenty-four hour clock day begins at 2300. The last minute of the hour begins at 2359 and ends at 0000, which is the beginning of the first minute ending at 0001 of the first hour of the next day.
Train and steamer services to and from the Continent, including the boat trains in England, have long had24hr clock indications, mainly to conform with the practice of connecting Continental railways, for Irish services are exempt.
Twenty-four-hour clock.—The use of the24-hour clock eliminates the use of a.m. and p.m. Giving the time from midnight to 12.59 remains unchanged; the remaining customary afternoon times are increased by 12.
1989, Jane Briehl, “Thirty-eight Activity Cards[Minute Math Card #2: The Twenty-four Hour Clock!]”, inAll about Time: Curriculum-based Activities for Telling Time & Much More!: Grades 4–6,[Napanee, Ont.]: S & S Learning Materials,→ISBN,page23:
Thetwenty-four hour clock is used by railroads, airports and the military because there is no need to add a.m. or p.m. The number on the clock immediately tells you if it is before or after noon. Eight thirty in the morning would be 08:30. Eight thirty at night would be 20:30.
2016, Caroline Potter, “Satie’s Texted Piano Works”, inErik Satie: A Parisian Composer and His World, Woodbridge, Suffolk: The Boydell Press,Boydell & Brewer,→ISBN,page130:
Whiting[i.e., Stephen Moore Whiting,Satie the Bohemian (1999), page 410] remarks that '[Erik] Satie was evidently fascinated by the phenomenon of the government changing the designation of hours through simple imposition of the24-hour clock. […] In 1952, René Chalupt recalled that Satie, "whenever he fixed the time of a meeting … would use both the new and old designation: 'I'll be there at 1800 hrs (6 o'clock old style)'".'[…] The benefits and drawbacks of thetwenty-four-hour clock were a topic of debate in early twentieth-century France. The guidebook of the Paris Exposition in 1900 states: 'Let's remember that Belgium is the only country to have officially adopted the24-hour clock, just as the Observatory of Paris has done since 10 January 1900.'
2024, Bernard K. Means, “Ring-shaped Settlements and Exploratory Circular Statistics: A Graphical Approach”, in Martin Menz, Analise Hollingshead, Haley Messer, editors,The Archaeology of Arcuate Communities: Spatial Patterning and Settlement in the Eastern Woodlands (A Dan Josselyn Memorial Publication), Tuscaloosa, Ala.:University of Alabama Press,→ISBN, part II (Organizing Principles of Arcuate Communities),page95:
With circular or directional data, there is no true zero. The lowest value in a circular distribution is the same as its highest value. Common examples cited to illustrate this point aretwenty-four hour clocks and twelve-month calendars.
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24-hour clock on Wikipedia.Wikipedia
, Oxford:Oxford University Press, September 2024.