This large concrete structure, one of two remnants of the Devlin Toluca Mine left today, housed the fan that ventilated the mine shaft and was essential to the miners. Toluca's Mine used the latest ventilation and fresh air systems, making it one of the safest mines in the area. Ventilation was crucial because accumulated methane gas could easily catch fire and cause an explosion, and the fan provided fresh air while diluting the gas. In 1893, ventilation in the mines was one of the biggest engineering problems, because a fire could consume the entire oxygen supply and suffocate the miners. Keeping safety in mind, Charles Devin installed fire doors in the main veins and placed steam-powered pumps, hoist equipment, and compressors in the mine, but the most important safety feature was escape exits. Three exits were available: one on the north side of shaft #1, a second on the ventilation shaft, and a third backup at shaft #2. Although there were several fires, these exits never had to be used. The worst fire caused the loss of a tower, scale house, and large coal bin at shaft #1, but mining operations resumed in two days by using shaft #2.