As Arthur and Merlyn discuss battle strategies on the battlements of Castle Camelot in Chapter 2 of The Queen of Air and Darkness, the pair see some men walking along the path below. Arthur offers to drop a rock on the head of one of the men, and—in a moment of dramatic irony—Merlyn understands what will happen:
'At thirty-two feet per second,' he said, 'I think it would kill him dead. Four hundred g is enough to shatter the skull.
Merlyn responds using language from Newtonian physics. He first refers to the speed of acceleration due to gravity, 32 feet per second, but expresses it incorrectly as a velocity. (It is unclear if this error is the fault of Merlyn or White.) Then Merlyn remarks that "Four hundred g is enough to shatter the skull": he is referring to "g-forces." Merlyn has calculated that the rock would hit the man's head with a force equal to 400 times the force of gravity on Earth.
This statement from Merlyn is intentionally anachronistic. Gravity would not be widely understood this way until the 17th century, and this book does not take place in the 17th century. Merlyn certainly makes many anachronistic statements, on account of his aging backwards. But this one is one of the few instances (if not the only one) in which the anachronism is not meant as a helpful teaching tool for Arthur. Merlyn does not attempt to explain the anachronism; in fact, it seems to be entirely for his own delight or intellectual enjoyment. This makes this particular version of Merlyn's anachronism especially effective because it uses dramatic irony: the audience knows things that some characters in the scene do not. Modern-day readers, understanding Newtonian laws of gravity, enjoy Merlyn's joke at Arthur's expense, none the wiser.
While the portents of battle gather outside on the plain of Bedegraine, Arthur stays inside the castle. Because he is deep in discussion with Kay, Ector, and Merlyn, it seems as though they are making a plan. But even in the hour of war, they are discussing other things; White plays this situation for laughs:
King Arthur paid no attention to the coming battle. He sat invisible in his pavilion, at the hub of the excitement, and talked to Sir Ector or Kay or Merlyn day after day. The smaller captains were delighted to think that their King was having so many councils of war, for they could see the lamp burning inside the silk tent until all hours, and they felt sure he was inventing a splendid plan of campaign. Actually the conversation was about different things.
This moment is funny because of the dramatic irony that White uses. The "smaller captains" thought Arthur was working hard on war planning. The fact that the audience knows Arthur is doing other things makes this dramatic irony.
White emphasizes this dramatic irony by withholding information of what Arthur is actually discussing. It is even more ironically funny that White only says (in this sentence) that the real conversation "was about other things." What Arthur and the others are talking about is so unimportant that White doesn't even bother to specify what it is. Given that the "smaller captains" think that Arthur is discussing complex war matters, this is quite the inversion of expectations. Later in the scene, we find that what Arthur was discussing was the shape of his table where all his knights will meet: should it be round or square? What about the space in the middle? These questions, at first, seem like especially inane, petty concerns when an enemy force is gathering just outside the castle gates. But readers learn that the Round Table will become a symbol of Arthur's understanding of justice and that the equal brotherhood of many strong knights can maintain safety in the land.
In sum, there are multiple layers of irony in this moment: the "smaller captains," watching the lights and activity in the "silk tent," think that Arthur and his knights are discussing the battle. In fact, they are discussing "different things," presented as unimportant by White. But these matters of table organization are themselves in fact important, as the Round Table will become an essential image in the novel.