These mares-tails are cirrus clouds, scattered in the zenith, their height from the sea being less than five thousand feet. They look like light pieces of cotton wool, and their presence usually announces some sudden change in the weather. "Well," said Harding, "let us carry as much sail as possible, and run for shelter into Shark Gulf. I think that the _Bonadventure_ will be safe there." "Perfectly," replied Pencroft, "and besides, the north coast is merely sand, very uninteresting to look at." "I shall not be sorry," resumed the engineer, "to pass not only to-night but to-morrow in that bay, which is worth being carefully explored." "I think that we shall be obliged to do so, whether we like it or not," answered Pencroft, "for the sky looks very threatening towards the west. Dirty weather is coming on!" "At any rate we have a favourable wind for reaching Cape Mandible," observed the reporter. "A very fine wind," replied the sailor; "but we must tack to enter the gulf, and I should like to see my way clear in these unknown quarters." "Quarters which appear to be filled with rocks," added Herbert, "if we judge by what we saw on the south coast of Shark Gulf." "Pencroft," said Cyrus Harding, "do as you think best, we will leave it to you." "Don't make your mind uneasy, captain," replied the sailor, "I shall not expose myself needlessly! I would rather a knife were run into my ribs than a sharp rock into those of my _Bonadventure_!" That which Pencroft called ribs was the part of his vessel under water, and he valued it more than his own skin. "What o'clock is it?" asked Pencroft. "Ten o'clock," replied Gideon Spilett. "And what distance is it to the Cape, captain?" "About fifteen miles," replied the engineer. "That's a matter of two hours and a half," said the sailor, "and we shall be off the Cape between twelve and one o'clock. Unluckily, the tide will be turning at that moment, and will be ebbing out of the gulf. I am afraid that it will be very difficult to get in, having both wind and tide against us." "And the more so that it is a full moon to-day," remarked Herbert, "and these April tides are very strong." "Well, Pencroft," asked Cyrus Harding, "can you not anchor off the Cape?" "Anchor near land, with bad weather coming on!" exclaimed the sailor. "What are you thinking of, captain? We should run aground to a certainty!" "What will you do then?" "I shall try to keep in the offing until the flood, that is to say, till about seven in the evening, and if there is still light enough I will try to enter the gulf; if not, we must stand off and on during the night, and we will enter to-morrow at sunrise." "As I told you, Pencroft, we will leave it to you," answered Harding. "Ah!" said Pencroft, "if there was only a light-house on the coast, it would be much more convenient for sailors." "Yes," replied Herbert, "and this time we shall have no obliging engineer to light a fire to guide us into port!"