Noel made Oswald a secret signal.

All the others saw it, and with proper delicate feeling pretended not to have.
When Oswald had gone out with Noel and H.O.in obedience to the secret signal, Noel said-- 'You know that dragon's head yesterday ?' 'Well ?' Oswald said quickly, but not crossly--the two things are quite different.
'Well, you know what happened in Greek history when some chap sowed dragon's teeth ?' 'They came up armed men,' said H.O., but Noel sternly bade him shut up, and Oswald said 'Well,' again.

If he spoke impatiently it was because he smelt the bacon being taken in to breakfast.
'Well,' Noel went on, 'what do you suppose would have come up if we'd sowed those dragon's teeth we found yesterday ?' 'Why, nothing, you young duffer,' said Oswald, who could now smell the coffee.

'All that isn't History it's Humbug.

Come on in to brekker.' 'It's NOT humbug,' H.O.cried, 'it is history.