1892. The self-acting greenhouse engine is a small vessel of cast iron, one part of which is filled with air, highly condensed by a piston, and the other with water, which, by turning the cock, is let out by a spout either as a shower or stream. The machine may be held in the hand, and the stream or shower directed against any particular plant. Instead of water, if tobacco-smoke be introduced, the smoke will be driven with great force to a considerable distance. This machine will throw the water from thirty to fifty feet, but its chief use is in greenhouses, for the purposes of fumigation, as a plant on the upper part of a stage may thus be fumigated without the operator being nearer it than the path. On the whole, it is more an instrument for the amateur than the practical gardener.