The sensations thus excited in the public mind, were by no means allayed, when, in the course of the day, the details of the horrible transaction began to develope themselves; every one felt a breathless anxiety to probe to the bottom the secret workings of so detestable a conspiracy, confidence between man and man became weakened, and that social intercourse which constitutes the peculiar charm of society in this happy country, seemed to be placed at the mercy of the midnight assassin; the only hope left to the upright and the loyal portion of the community was, that the discovery would finally terminate in the beneficial result of purging society of some of the foulest members that apparently ever moved in it. For some time previous to the day on which the arrests took place, it had been known to his Majesty’s government, that an attempt at the assassination of his Majesty’s ministers was meditating, and that Arthur Thistlewood was at the bottom of it. On Tuesday, the 22d of February, certain advice was received, that the attempt was to be made on Wednesday night, at the Earl of Harrowby’s, in Grosvenor-square. It is supposed that the Earl of Harrowby’s was fixed upon, because, being nearer the outlet from London than the residence of any other of the cabinet ministers (Lord Westmoreland’s excepted, who lives in the same square,) escape out of town, after the attempt had been made, would have been more easy. Be this as it may, the conspirators, as soon as they had ascertained that the cabinet dinner was to be held there, lost no time in arranging their dreadful and diabolical project. The place chosen to arrange finally their proceedings, to collect their force, and to arm themselves, was near the Edgeware-road. John-street is a short distance on the road, and intersected by another street, called Cato-street. Cato-street is rather an obscure street, and inhabited by persons in an humble class of life; it runs from John-street into Queen-street, and is parallel with Newnham-street. It is open at one end for the admission of carriages, but is closed by posts at the other. The premises occupied by the conspirators consisted of a three-stall stable, with a loft above, in a very dilapidated condition. They are the property of General Watson, and have been recently in the possession of an old servant of his, who had turned cow-keeper. From this man they had been engaged by some of the diabolical crew whose machinations have been so happily discovered. The people in Cato-street were utterly ignorant that the stable was let until Wednesday, when several persons were seen to go in and out, and carefully to lock the door after them. Some of these individuals carried sacks, and parcels of various descriptions.