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When weather conditions are right, with freezing nights followed by warm days, a small percentage of the sap in the tree comes out of the taphole to be collected.

Over an entire season, Mr. Farrell said, the yield of sap can range from about five to 20 gallons per taphole, depending on the tree’s size and health, the weather conditions that spring and the type of collection system.

After the sugaring season is over, the spout is pulled from the taphole and the tree wound is able to heal, he said.

Mechanical Furnaces.—The introduction and withdrawal of the charges in fusion furnaces is effected by gravitation, the solid masses of raw ore, fuel and flux being thrown in at the top, and flowing out of the furnace at the taphole or slag run at the bottom.

This is drawn off through the taphole D. The carbon monoxide formed in the reaction escapes through the pipes E and is led back into the furnace.