Petroleum (p-tr´ l-m) lies in great deposits usually far below the surface of the earth. The deposit is tapped by drilling. With the petroleum is usually a heavy deposit of gas which forces the oil to the surface. Sometimes these wells are great "gushers", the oil spouting many feet above the surface. In others the oil flows very slowly, and in these it is necessary to enlarge the bottom of the well by explosives. Then, too after a "gusher" has flowed for a long time, its output becomes weak, and the flow is strengthened by blasting. The view shows the preparation for setting off one of these big blasts. A can that will fit the inside of the pipe in the well is filled with nitro-glycerin (n´ tr-gls´ r-n). This is a powerful explosive, and is very readily discharged. Should the man you see accidentally drop the can of nitroglycerin he holds, like The Three Men in the Tub, "Our tale would be ended". The large cans which are let down in the wells contain from 60 to 200 quarts of nitroglycerin. These large cans are built in sections so that the length of the combined cans is 8 to 10 feet. These cans are fastened together and a torpedo is placed on the top of the upper one. The cans are then lowered all together to the bottom of the well. A device lets a weight drop from the top of the well to the top of the can. This weight is called a go-devil. When it hits the torpedo, a tremendous explosion follows. You will observe some of the machinery connected with the derrick. This derrick is needed when the well is dug, or for successive drillings. Usually no damage happens to it when a well is "shot". Explain why oil wells are "shot". Keystone ID: 20058 Note: All titles, descriptions, and location coordinates are from the original Keystone Slide documentation as supplied by the Keystone View Company. No text has been edited or changed.