Butler and Sheridan — Account of a New Oedanometer. 476 



Taki.e T. 



111 A and B the initial pressure was low (about two atmospheres), while 

 in C and D a pressure of about ten atmospheres was applied at the start. In 

 all four eases the beans germinated when set aside in suitable conditions. 



Three experiments carried out with peas, six being used at a time, gave 

 maximum pressures of 50'3, 49, and 48-5 atmospheres. 



Fig. 4 shows a simple apparatus which we set up to obtain the pressures 

 exerted by a mass of swelling seeds. It is a modification of Maedougal's 

 apparatus to which we have previously referred. It consists of a piece of 

 three-inch gun-barrel tubing E, screwed to the lower end of which is the 

 reducing coupling F. 



To the lower end of this coupling is connected the tube KL, and attached 

 to this is a rubber tubing from the water-supply. Three pieces of rod, one 

 of which is shown at M, are screwed into the coupling F, and act as leo-s 

 supporting the apparatus. A grating H and a wire gauze G serve to 

 distribute the water at the inlet. The seeds are packed with sand and 

 gravel as in the first apparatus. The pressure is registered by means of 

 a rubber bag 11 containing mercury (a small football tube acts well) con- 

 nected with the manometer (A) made of thermometer tubing of 1 mm. 



