THE British Broadcasting Corporation will adopt the 24-hour system of expressing time from April 22, when ‘summer-time’ commences in Great Britain. The system will be used in all announcements over the microphone, in the journals published by the Corporation and in correspondence. No statement has been made as to the duration of the trial of the system, but it will doubtless be sufficiently long for the public to become thoroughly familiar with the system and for the extent of public approval or disapproval of the system to be gauged. As already announced in NATURE, the Postmaster-General will await the result of this experiment before coming to a decision on the question of the adoption of the system in the Post Office. It is proposed by the B.B.C. that a time such as 17 h. 15m. shall be announced as ‘Seventeen-fifteen hours’. This terminology would be inaccurate and undesirable, and it is to be hoped that such a designation will not be used; otherwise this phraseology may soon become stereotyped. The expression ‘seventeen hours fifteen minutes’ is accurate but long: ‘seventeen hours fifteen’ is a contraction analogous to ‘seventeen pounds fifteen’ for £17 15s. Od. But ‘seventeen fifteen’ (analogous to the present 5.15 p.m., but with the now unnecessary p.m. dropped) should be quite sufficient. At the exact hour, 17 hours can be used as simpler than 17.00.