twelve o'clock
`` It is so short and stubby that all the dust gets into it and to save my life I ca n't help sneezing . And I always do it at the most inopportune moment . '' Just then a whistle sounded , and Tiger said , `` We must hurry ! There goes the twelve o'clock whistle at the factory down the river . It is the signal for the night shift to come on . '' -LSB- Illustration -RSB- The warehouse being near where they were , in about five minutes they found themselves entering the low window Buster had spoken about . When they looked inside , it was pitch dark and as if they were looking into a coal pit .