Petitioner manufacturer of goods for interstate commerce held liable to fireguard employees for overtime, liquidated damages. Justice Jackson delivered the opinion holding that the Labor Standards Act does not exclude, as working time, periods contracted for and spent on duty merely because the nature of the duty left idle time on the employees' hands and because the employer and employee cooperated in trying to make the confinement and idleness incident to it more tolerable. Certainly they were competent to agree, expressly or by implication, that an employee could resort to amusements provided by the employer without a violation of his agreement or a departure from his duty. Both courts below having concurred in finding that, under the circumstances and the arrangements between the parties, the time so spent was working time.