A MANOMETER METHOD OF DETERMINING THE 

 CAPILLARY PULL OF SOILS 



W. A. CANNON 



The Desert Laboratory, Tucson, Arizona 



The apparatus to be briefly described has been in use by the 

 writer at the Desert Laboratory for two years and has been 

 found of service as a convenient means of determining the capil- 

 lary pull of soils used in experimental work. No attempt is 

 here made to relate the results to be given with results achieved 

 by using the direct method of measuring the ascent of water, 

 which is the method commonly employed. Whether the results 

 of the two means of determining the capillarity are comparable, 

 as they possibly are, is not germane to the present purpose. 



As used the apparatus is very simple and can be put together 

 in a few minutes in any laboratory. It consists, in brief, of a 

 U-shaped mercury manometer, with open ends, and a soil con- 

 tainer holding about 500 cc, and, in addition, a reservoir of about 

 500 cc. capacity for water. The reservoir is connected with a 

 T-shaped glass tube having a three-way cock. A rubber tube 

 connects one free end of the T-tube with the manometer, and 

 another rubber tube, which should be relatively long, connects 

 the third end of this tube with the soil container. The various 

 portions are easily attached by clamps to a horizontal iron rod 

 which is fastened to a ring-stand. 



When the several parts of the apparatus are assembled water 

 is put in the reservoir and the whole is so manipulated that 

 water, to the exclusion of any air, fills the tubes which unite the 

 container, the reservoir, and the manometer. The reservoir 

 and the container are about on the same level so that, if the cocks 

 are left open, water will stand equally near the upper edges of 

 both. 



After the rubber tubes and the uniting glass tubes are filled 

 with water the reservoir should be somewhat more than half 



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