midnight
Laboratory and `` Yellow Room '' are in a pavilion at the end of the park , about three hundred metres -LRB- a thousand feet -RRB- from the chateau . ``` It was half-past twelve at night , ' this honest old man told us , ` and I was in the laboratory , where Monsieur Stangerson was still working , when the thing happened . I had been cleaning and putting instruments in order all the evening and was waiting for Monsieur Stangerson to go to bed . Mademoiselle Stangerson had worked with her father up to midnight ; when the twelve strokes of midnight had sounded by the cuckoo-clock in the laboratory , she rose , kissed Monsieur Stangerson and bade him good-night . To me she said `` bon soir , Daddy Jacques '' as she passed into `` The Yellow Room '' . We heard her lock the door and shoot the bolt , so that I could not help laughing , and said to Monsieur : `` There 's Mademoiselle double-locking herself in , -- she must be afraid of the ` Bete du bon Dieu ! ''' Monsieur did not even hear me , he was so deeply absorbed in what he was doing .