The barges on which Captain Heinde and his 300 men embarked were primitive specimens of the boat builders' art, previously used for the transportation of freight. Unlike the ordinary coal barge, these were roofed in, and, were it not for the flat roof, would have exactly resembled Noah's ark. They measured 125 feet long and 20 feet wide. One was known as the Iron Mountain; the other as the Monongahela. These floating barracks had been purchased a week before the time of the Pinkerton expedition by an agent of Mr. Frick's, and quietly fitted up at the landing-place of the Tide Coal Company, in Allegheny City. The Iron Mountain was equipped as a dormitory, several tiers of berths being constructed on both sides and furnished with bed clothes. Two rows of cots occupied the middle of the floor. The Monongahela was converted into a vast dining-room. Two rows of tables were placed in the middle and board seats were provided. In the stern was a commodious kitchen, with a full outfit of stoves and cooking utensils. An experienced steward and a corps of twenty waiters were employed. At the last moment a number of mysterious looking cases were put on board. These contained Winchester rifles and had been forwarded to the Carnegie Company by Adams Express. Watchmen at the landing met all inquiries with the explanation that the barges were intended for the transportation of laborers to the Beaver dam on the Ohio River. It has been said that most of the Pinkerton men had no idea of the nature of their mission. The fact is that only the officers of the expedition comprehended the gravity of the work in hand. However, when the men found themselves being conveyed up the river in the close quarters which the barges afforded to so large a number, many of them became uneasy, and, weary as they were after their long trip by rail, but few were able to close an eye. As the barges approached the mouth of the Monongahela River, the lights of the two great cities of Pittsburgh and Allegheny illuminated the surface of the waters; but no midnight wayfarer who saw the Little Bill and the Tide, with their odd-looking tows, dreamt for an instant that within those coffin-like craft was the Frick army of invasion and that, within a few hours, those same craft would harbor terror, bloodshed and death. The two cities slept on, unconscious of the thunderbolt that was to fall at the dawning of the day.