The finished gunpowder was taken to the next building, one thousand five hundred feet beyond, up the canal, where it was weighed out and put into strong wood boxes about two and a half feet long, by one foot square, having the ends let into grooves; one of the ends had a strong wood screw, two inches diameter, with an octagonal head. Experience proved that these powder boxes, a devise of my own from necessity, were superior to barrels, being stronger, occupying less room, standing transportation better, and safer in use. No explosion ever occurred in their transportation, notwithstanding the occasional Railroad accidents, and the many thousands that were sent from the Powder Works during the war. The powder boxes being filled, were then transported to the magazine, three quarters of a mile still further up the canal. This wood structure was on a rising ground one hundred yards from the canal, enclosed by a high fence. Its capacity was about one hundred tons of gunpowder. At this, and every other separate building of the Powder Works, a sentinel was stationed day and night, and the utmost vigilance used. Also, each of the separate buildings along the canal, except the magazine, containing large amounts of gunpowder, were enclosed with high brick walls, having a single entrance. At the Waltham Abbey Works, in England, the gunpowder cake after being crushed, is subjected to compression by the hydraulic press to give it sufficient density. I found that by using five ton rollers, the proper compression could be given in the powder mills during the incorporation, thus saving much labor and time. The hydraulic press, consequently was only used to compress the powder dust into thin cakes, which were sent to the granulating department to be used for fine grain powder only. The press house was located between the Cooling Magazines and the granulating building on the same side of the canal as the former. It was a large brick structure provided with two hydraulic presses, cranes, and other appliances, with a turbine water wheel to supply the required motive power. After the discovery that the proper density could be better given to the powder cake, by using sufficiently heavy rollers during the incorporation, this department was used only for the purpose above stated. The interval of ninety feet between the Refinery building and the Incorporating Mills, was mainly occupied by a fine building called the Laboratory. It had a projecting tower in the front centre, twenty-five feet square at the lower stories, which together were forty-five feet in elevation. From this the upper portion fifteen feet square ascended to the height of thirty feet, making seventy-five feet in all. The upper part of this constituted the clock tower with its four large circular openings for dials. These could be seen for a long distance.