midnight
By daylight the young engineer might have noted its weak spots , and strengthened them . He would have seen the thin streams that silently , but steadily and in ever-increasing volume , were working their way through the embankment near its base . In the inky blackness of the night they were unheeded ; and while spade and pick were plied with unflagging zeal to strengthen the higher portions , these insidious foes were equally busy undermining its foundations . Shortly before midnight everything seemed so secure that the boys were sent to the _ Venture 's _ `` shanty '' to get a few hours of sleep . Then Billy Brackett and Mr. Manton came in for the hot coffee Solon was preparing for them . They had hardly seated themselves at the table when the catastrophe occurred . Without warning , a quarter of a mile of the water-soaked levee sank out of sight , and dissolved like so much wet sugar .