How was a criminal executed in brodingnag?

On Brobdingnag, Gulliver receives the dubious honor of being invited to an execution. Gulliver's normally averse to such grisly spectacles, but his curiosity gets the better of him and he agrees to go along. The criminal in question is a murderer, and as is customary on Brobdingnag, he is to be beheaded for his wicked crime. The murderer is sat down in a large chair upon a scaffold, where he will subsequently be decapitated. The execution itself is mercifully swift, the murderer's head being removed with one quick, single blow from a sword forty feet in length.
After the deed is done, a huge spurt of blood and assorted viscera shoots into the atmosphere like a great fountain at Versailles. The executed murderer's head tumbles down onto the scaffold floor, causing the ground to shake beneath Gulliver's tiny feet, even though he's standing at least half a mile away.