# The Coal and Other Mines (Ventilation) Order 1956, Paragraph 4


(1) Determinations of the firedamp content shall be made—
(a) by means of apparatus of a type approved for the purpose by the Minister, by a competent person appointed for that purpose by the manager of the mine; or
(b) by means of samples of air taken by a competent person so appointed and analysed within four days of the taking thereof.
(2) In reckoning a period of four days for the purposes of this regulation no account shall be taken of any Saturday, Sunday or day of general holiday.

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Source: https://www.legislation.gov.uk/uksi/1956/1764/schedule/FIRST/paragraph/4 (the official version)
Page: https://openlegislation.uk/coal-and-other-mines-ventilation-order-1956/schedule-FIRST/paragraph-4
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.