The much-talked-of ball took place on the 15th June, 1815, ninety years ago yesterday. At three o'clock in the afternoon of that day a messenger arrived with important news for the Duke of Wellington that Napoleon at the head of his army had crossed the Sambre that morning, and had forced the Prussians to retire through Charleroi and Fleurus to a position near Ligny. The Duke immediately sent off orders for his troops to hold themselves in readiness to move, but not to advance. The latter he delayed until the evening, when reports from Mons had satisfied him that the attack was not a feint, and that Napoleon really had taken the Charleroi road. The critical state of affairs did not prevent the Iron Duke from attending the ball. On the contrary, he not only went himself, but he encouraged his officers to attend, thinking that their presence there would have a reassuring effect on the people of Brussels. In the room, the coachmaker's store improvised for the occasion, were assembled some two hundred guests, including ladies well known in English society, and most of the Duke of Wellington's staff--the Prince of Orange, the Duke of Brunswick, Lord Hill, Sir Thomas Picton, Sir Henry Clinton, the Earl of Uxbridge, Lord Edward Somerset, Sir Hussey Vivian, Sir William Ponsonby, Sir Denis Pack, and others. The news had spread that the French army was about to cross the frontier, and it caused a very natural sensation, but the dancing was not interrupted. Indeed, we are told that it was maintained with unusual spirit, as if to make the most of the enjoyment which was so soon to be interrupted. An interesting incident occurred which does not appear to have been recorded. During an interval in the dancing, a party of non-commissioned officers of the 92nd Highlanders, headed by their pipers, proudly marched into the room, having been specially invited to give an exhibition of the reel to her Grace's British and foreign guests; never did these Gay Gordons dance with greater grace, or to a more appreciative audience.