eight o'clock
And so the explosive substance with which poor Ruby had so grievously imperiled the vessel was now to serve her in good stead , and I now saw what a lucky thing it was that the case had been deposited safely on the reef , instead of being thrown into the sea . The sailors went off at once for their pikes , and Dowlas and his assistants , under the direction of Falsten , who , as an engineer , understood such matters , proceeded to hollow out a mine wherein to deposit the powder . At first we hoped that everything would be ready for the blasting to take place on the following morning , but when daylight appeared we found that the men , although they had labored with a will , had only been able to work for an hour at low water and that four tides must ebb before the mine had been sunk to the required depth . Not until eight o'clock on the morning of the 23d was the work complete . The hole was bored obliquely in the rock , and was large enough to contain about ten pounds of explosive matter . Just as the picrate was being introduced into the aperture , Falsten interposed : `` Stop , '' he said , `` I think it will be best to mix the picrate with common powder , as that will allow us to fire the mine with a match instead of the gun-priming which would be necessary to produce a shock . Besides , it is an understood thing that the addition of gunpowder renders picrate far more effective in blasting such rocks as this , as then the violence of the picrate prepares the way for the powder which , slower in its action , will complete the disseverment of the basalt . ''