68 MANAGEMENT OF THE FORCING-HOUSE, 
dull spells of midwinter. In such weather, plants tend 
to grow soft and succulent, a tendency which is aided 
by over-watering. If there is a sudden rise in tempera- 
ture and a spell of bright weather, such flabby plants are 
likely to flag, scorch, curl, or otherwise suffer. It is, there- 
fore, extremely important that the gardener should aim to 
keep his plants ‘“‘hard”’ in these cloudy days. 
In cold weather, the chill should always be taken off 
the water before it is applied to soil in which ‘‘ warm” 
plants —like cucumbers, melons, tomatoes and egg-plants — 
are growing; and it should also be done with lettuce if 
the hose water is colder than 60°. There are devices (of 
which the so-called Kinney pump is a good example) for 
drawing hot water from a tank or pail into the hose in 
just the right proportion to temper the water; or, if the 
establishment is not too large, a watering-pot may be 
used. In large establishments, where steam power is 
used, an arrangement can be perfected for ejecting steam 
into the water. Rain water is undoubtedly the best water 
for plants, but ordinary spring or reservoir water is not 
injurious, and is generally used. 
WATERING BY SUB-IRRIGATION. 
Recent experiments have shown that water may be 
economically and efficiently applied to forced plants by 
means of pipes laid in the bottom of the bench. The 
writer’s attention was first called to this line of investi- 
gation in 1890, when certain studies were proposed to 
determine what relation the supply of soil water has 
to the transpiration of water from the foliage and to the 
consequent rate of growth of the plant. Experiments 
were begun at Cornell in 1891, but facilities were not at 
hand to continue them. In this same year, Mr. W. J. 
Green published preliminary results of somewhat similar 
and more important experiments at the Ohio Experiment 
Station, and his investigations were begun in 18go, in 
