132 STEPHEN HALES 



His first experiment (Vegetable Staticks, p. lOo), 

 was with a vine, to which he attached a vertical 

 pipe made of three lengths of glass-tubing jointed 

 together. His method is worth notice. He 

 attached the stump to the manometer with a "stiff 

 cement made of melted Beeswax and Turpentine, 

 and bound it over with several folds of wet bladder 

 and pack-thread." We cannot wonder that the 

 making of water-tight connexions was a great 

 difficulty, and we can sympathise with his belief 

 that he could have got a column more than 21 feet 

 high but for the leaking of the joints on several 

 occasions. He notes the familiar fact that the 

 vine-stump absorbed water before it began to 

 extrude it. 



He afterwards (pp. 106-7) used a mercury 

 gauge, and registered a root-pressure of 32 J inches 

 or 36 feet s\ inches of water, which he proceeds to 

 compare with his own determination of the blood- 

 pressure of the horse (8 feet) and of other animals. 

 Perhaps the most interesting of his root-pressure 

 experiments was that (p. iio) in which several 

 manometers were attached to the branches of a 

 bleeding vine, and showed a result which convinced 

 him that "the force is not from the root only, but 

 must proceed from some power in the stem and 

 branches," a conclusion which some modern 

 workers have also arrived at. 



Assimilation. 

 Hales' belief that plants draw part of their food 

 from the air, and again, that air is the breath of life, 

 of vegetables as well as of animals (p. 148), are 



