The suit for divorce was opened in the Westminster Divorce Court February 16th, 1869, and some of the most eminent and aristocratic personages in England attended. The Prince of Wales was ashamed to be present until sent for, but as he was very anxious about the result he sent his private Secretary, Sir W. Knollys, to watch the case. That gentleman was present every day, and manifested great interest in the testimony, which was very filthy, but not so filthy but that the Pall Mall Gazette and London Times, with other leading journals, should print every line of it, day by day, as it transpired in the Court. The trial continued seven days, Lord Penzance presiding, and it created as great an interest in London as the McFarland and Richardson case did in New York. No ladies were admitted to the Court, but two thousand, the majority of whom were of the cultivated and respectable class, sought admission during the first three days of the trial. All the relatives, of both parties, who could attend were present. The Dowager-Lady Mordaunt, mother of Sir Charles, testified strongly against her daughter-in-law, whom she accused of shamming insanity to hide her crime and dishonor. The plea of insanity was the defence set up by Sir Thomas Moncrieffe, father of Lady Mordaunt. The testimony was very contradictory. Some of the physicians swore that Lady Mordaunt was perfectly sane, but that she feigned insanity to screen herself, while others testified that she was not in a sound condition of mind. [Sidenote: A TREACHEROUS WIFE.] But the evidence was very clear against Lady Mordaunt despite of all endeavors to save her, or rather to save the Prince of Wales, through the unfortunate lady. Testimony was adduced, that, one evening in November, 1868, Lady Mordaunt absented herself from Walton Hall and went to London in company with Captain Farquhar, one of her "fast" young male friends, and that while there she stopped a whole night with him at the Palace Hotel. To blind her husband she wrote the following note to him: Palace Hotel, Buckingham Gate, Nov. 8. My Darling Charlie--One line to say I shall not be able to reach home by twelve o'clock train, but will come by the one which reaches at 3.50. Send carriage to meet me. I felt horribly dull by myself all yesterday evening. I have not had much time as yet to-day. I have seen Priestly and will tell you all about it when I come home. Your affectionate wife, HARRIET MORDAUNT. Frederick Johnson, a footman of Lady Mordaunt, testified as follows: