Towards the end of 1793, several meetings of the British Convention were held in Edinburgh. At one of them (5th December) the Magistrates interfered, dispersed the Convention, and apprehended ten or twelve of the members, among whom were several English delegates; but who, after examination, were liberated on bail. The Magistrates at the same time issued a proclamation, prohibiting all such meetings in future; and giving notice to all persons "who shall permit the said meetings to be held in their houses, or other places belonging to them, that they will be prosecuted and punished with the utmost severity of the law." Notwithstanding this proclamation, another meeting was summoned by the secretary, William Skirving, to be held in the cockpit, Grassmarket, on the 12th of December. On this occasion the Magistrates again interfered, and apprehended several of the members ; some of whom were served with indictments to take their trial before the High Court of Justiciary. It was about this time that Watt and Downie became deeply involved in those transactions for which they were condemned. After the dispersion of the British Convention, they became active members of a " Committee of Union," designed to collect the sense of the people, and to assemble another Convention. They were also members of a committee, called the "Committee of Ways and Means"—of which Downie was treasurer. In unison with the sentiments of the London Convention, it appears, the "Friends of the People" in Edinburgh had abandoned all hope of, or intention of further demanding, redress by constitutional means; and the more resolute of them began to entertain designs of an impracticable and dangerous nature. Of these wild schemes Watt was a principal and active promoter.

The first attempt of the Committee was to gain the co-operation of the military, or at least to render them neutral; for which purpose they printed an address, and circulated a number of copies among the Hopetoun Fencibles, then stationed at Dalkeith. The regiment was about to march for England. The object of the address was to excite the men to mutiny, by persuading them that they were sold to go abroad; and that, if they revolted, they would get thousands to assist them. John Geddes, a witness, and one of the soldiers, said he read the address. Some of the words it contained were—"Stay at home! O! dear brothers, stay at home!" A plan was also formed, by which it was expected that the city, together with the Castle, would fall into the hands of the "Friends of the People." The design was as follows:

"A fire was to be raised near the Excise Office, which would require the attendance of the soldiers, who were to be met on their way by a body of the "Friends of the People;" another party of whom were to issue from the West Bow, to confine the soldiers between two fires, and cut off their retreat. The Castle was next to be attempted; the Judges and Magistrates were to be seized; and all the public banks were to be secured. A proclamation was then to be issued, ordering all the farmers to bring in their grain to market as usual; and enjoining all country gentlemen unfriendly to the cause to keep within their houses, or three miles of them, under penalty of death. Then an address was to be sent to his Majesty, commanding him to put an end to the war—to change his ministers—or take the consequences."

Before this extraordinary project could be carried into effect, it was necessary that arms, of some description or other, should be procured. Another committee was consequently formed, called the collectors o( "Sense and Money," whose business it was to "raise the wind," in order to procure arms. Two smiths (Robert Orrock and William Brown), who had enrolled their names among the "Friends of the People," were employed to make four thousand pikes; some of which were actually completed, and had been delivered to Watt, and paid for by Downie, in his capacity of treasurer.

Meanwhile the trials of William Skirving, Maurice Margaret, and Joseph Gerrald had taken place; but it was not until May that Walt and Downie were apprehended. On the 15th of that month, two sheriff-officers, while searching the house of Watt for some goods which had been secreted, belonging to a bankrupt, discovered some pikes, which they immediately carried to the Sheriff's Chambers. A warrant was then given to search the whole premises, and also to apprehend the parties. In the cellar, a form of types, from which the address to the military had been printed, as also an additional quantity of pikes, were discovered; and in the house of Orrock, the smith, thirty-three pikes, finished and unfinished, were likewise found.

True bills of indictment having been found against Watt and Downie, the trial of the former took place before the Court of Oyer and Terminer, on the 14th of August, 1794; and of the latter, on the 7th of September. The facts set forth in the indictments were fully proven against the prisoners. A letter from Downie—as treasurer to the Committee of Ways and Means, to "Walter Millar, Perth"—acknowledging the receipt of £15, in which he gave an account of the riots in the Theatre, was produced and identified; and Bobert Orrock stated that Downie accompanied Watt to his place at the Water-of-Leith, when the order was given for the pikes. William Brown said he made fifteen pikes by Watt's order, to whom he delivered them; and that, on a line from Watt, Downie paid him twenty-two shillings and sixpence for the fifteen. Margaret Whitecross, who had been at one time a servant of Mr. Downie, on being shown one of the pikes, declared that she saw a similar one in Mr. Downie's house one morning when she was dressing the dining-room: that Mr. Downie had come home late the previous night: that Mr. Downie's son, Charles, came out of an adjoining closet, where he slept, as soon as he heard her in the room, and took it away; and at this time he had only part of his clothes on, and did not seem to have any other business in that room: that she remembers hearing Mrs. Downie ask her husband what he had done with the large dividing-knife which was found in the dining-room?—to which he answered, that he had locked it by: that she never heard her master speak of having such weapons to defend himself; and when she saw it, she thought she never saw such a dividing-knife before." A verdict of guilty was returned on both occasions ; and sentence of death passed upon the prisoners.

Watt suffered the extreme punishment of the law, according to the form usual in treasonable cases. Previous to his execution, he made a confession of the extent and purport of the measures contemplated by the Committees.

The execution of "Watt, which took place at the west end of the Luckenbooths, was conducted with much solemnity. He was conveyed from the Castle on a black-painted hurdle, drawn by a white horse, amid a procession of the magistracy, guarded by a strong military force. The prisoner, who was assisted in his devotions by the Rev. Principal Baird, exhibited a picture of the most abject dejection. He was wrapped in a great-coat, a red nightcap (which, on the platform, he exchanged for a white one), with a round hat, his stockings hanging loose, and his whole appearance wretched in the extreme. He was about the age of thirty-six, and was the natural son of a gentleman of fortune and respectability, in the county of Angus, but, as is usual, took the name of his mother. At about ten years of age he was sent to Perth, where he received a good education; and, at sixteen, he engaged himself with a lawyer; but, from some religious scruples, took a disgust at his new employment; and, removing to Edinburgh, was engaged as a clerk to Mr. E. Balfour, bookseller, whose shop is now occupied by the Journal Office, and with whom he lived for some years, without any other complaint than the smallness of his salary. Being desirous of becoming a partner of the business, he, by the influence of some friends, prevailed on his father to advance money for that purpose; and then made proposals to his employer; but his offer was rejected. Having money in possession, he entered into the wine and spirit trade, and for some time had tolerable success; but was ruined, it was said, on the commencement of the war with France.

Downie was pardoned on condition of banishing himself from the British dominions, and he died in exile. He was married, and had a family. He bore a respectable character as an honest and industrious tradesman, and had been twenty-four or twenty-five years a member of the Corporation of Goldsmiths, during a considerable period of which he held the office of Treasurer to the Incorporation. His shop was in the Parliament Square.