"G. B. D.," Yonkers, N. Y., says: "Will you please inform me if a flue 100 feet long will work? I have been told it will not. And would you please state if there are any books published with nothing but the plans of greenhouses?"

[A hundred feet flue will work as well as a short one, if the upright part or chimney is carried up right over the furnace. If a damper is put in the horizontal part of the flue, near its junction with the upright, just back of the furnace, so that the upright would be well warmed and dried before sending the fire round the horizontal portion, we believe a thousand feet could be warmed as well as a hundred. There is no work solely on greenhouse plans. - Ed. G. M].