"I don't see anything to laugh at, you young rascal," he said to Bob. "I'm sure I've given you quite as good a definition as you would find in any of those `catechisms of common things'--catechisms of conundrums, I call them--which boys and girls are made to learn by rote, like parrots, without really acquiring any sensible knowledge of the subjects they are supposed to teach! I might tell you, as these works do, that `steam was an elastic fluid generated by water when in a boiling state'; but, would you be any the wiser for that piece of information, eh?" "No, Captain," answered Bob, still giggling, "I don't understand." "Or, I might tell you `steam: is only a synonym for heat, the cause of all motion'--do you understand that?" Bob still shook his head, trying vainly to keep from laughing. "Of course not," cried the Captain triumphantly, "nor would I, either, unless I knew something more about it; and to tell you that would take me all the day nearly." "Oh spare us," said Mrs Gilmour plaintively. "Pray spare us that!" "I will, ma'am," he replied. "I assure you I wasn't going to do it. Some time or other, though, this young shaver shall come along with me when one of the new ships goes out from the dockyard for her steam trials; and then, perhaps, he will be able to have everything explained to him properly, without boring you or bothering me." "How jolly!" ejaculated Bob. "I should like that." "You mustn't count your chickens before they're hatched," growled the other, turning round on him abruptly; "and, if ever I catch you sniggering again when I'm talking I'll--I'll--" What the Captain's terrible threat was must ever remain a mystery; for, just at that moment, Nell, who had been looking over the side of the steamer, watching the creamy foam churned-up by her paddles and rolling with heavy undulations into the long white wake astern marking her progress through the water, suddenly uttered an exclamation. "Look, look, aunt Polly!" she cried excitedly. "Oh, look!" "What, dearie?" inquired Mrs Gilmour, bending towards her, thinking she had dropped her glove or something into the sea. "What is it?" "There, there!" said Nellie, pointing out some dark objects that could be seen tumbling about in the tideway some distance off the starboard quarter. "See those big fishes, auntie! Are they whales?" It was the Captain's turn to laugh now. "Whales, eh? By Jove, you'll be the death of me, missy, by Jove, you will, ho-ho-ho!" he chuckled, leaning on his stick for support. "What does Shakespeare say, eh? `very like a whale,' eh? Ho-ho-ho!" Miss Nell did not like this at all, though she did not object to laughing at others. "Well, what are they?" she asked indignantly. "What are they?" "Pigs;" replied the Captain with a grave face, but there was a sly twinkle of his left eye approaching to a wink. "Those are pigs, missy."