Apbil 16, 1909] 



SCIENCE 



623 



are renewed by accession of lower soil to tte 

 plowed portion. 



For the purpose of conducting investiga- 

 tions of this kind there have been built on the 

 farm at Cornell University a number of large 

 tanks in which soil may be kept at the same 

 surface level, and under conditions nearly 

 identical with that of the surrounding soil, 

 upon which duplicate tests are made. They 

 are intended to furnish receptacles for 

 bodies of soil of sufEicient size to produce 

 plants in a normal manner under approxi- 

 mately field conditions, and yet afford oppor- 

 tunity for measuring a large number of the 

 factors affecting plant growth. The con- 

 struction is of concrete, but the tanks will be 

 lined. 



Each tank is four feet two inches square 

 with a maximum vertical depth of four feet 

 six inches and a minimum depth of four feet. 

 There are twenty-four tanks placed in two 

 rows of twelve tanks each. Between the 

 rows of tanks is a tunnel, the bottom of which 

 is ten feet below the top of the tanks. The 

 tunnel is six feet wide. From the lowest 

 point in each tank is an outlet tube two 

 inches in diameter and tin lined. It is made 

 large enough to permit of easy cleaning and 

 has no bends in it. A piston runs through 

 the tube to within four inches of the upper 

 end. Between the perforated head of the 

 piston and the soil, glass wool is to be in- 

 serted. The piston can be withdrawn if it 

 is desired to clean the tube. 



Drainage water from each tank will be 

 caught in a receptacle in the tunnel. The 

 lining in the tanks will prevent any soluble 

 material in the concrete from appearing in 

 the drainage water. A constant water table 

 at any desired depth may be maintained by 

 raising the rubber tube leading from the out- 

 let tube to a corresponding point below the 

 surface of the soil in the tank. 



The tanks, as described, will each contain 

 between three and four tons of soil, and the 

 surface will constitute approximately .0004 of 

 an acre. They are built with special refer- 

 ence to durability so that it will be possible 

 to plan for experiments to extend over a long 

 period. The quantity of soil contained is not 



too large to allow of accuracy in sampling and 

 yet is sufficiently large to closely resemble 

 field conditions, which is not true of the 

 quantity contained in pots. No covering is 

 to be placed over the tanks, but in every way 

 natural conditions are to be permitted. The 

 top soil and subsoil will be placed in their 

 relative positions. It is expected that the 

 rainfall will be sufficient to meet the needs of 

 the crops, but if the plants suffer during 

 periods of drought they can be watered arti- 

 ficially. 



Any desired type of soil may be used which 

 is not possible with ordinary field experiments. 

 It is also possible to make a comparison of 

 different soil types under any desired con- 

 dition which may be very serviceable in ascer- 

 taining the effect of those properties differ- 

 entiating these types upon certain factors in 

 soil productiveness. 



The chief feature of the plan is that of 

 keeping accurate records of the factors af- 

 fecting plant growth without producing 

 artificial conditions. 



The tube leading from the bottom of the 

 tank is designed to carry off the drainage 

 water into a receptacle which will permit the 

 quantity to be measured and its constituents 

 to be determined. 



The accompanying diagram shows the plan 

 and cross-section of these tanks. 



T. L. Lyon 



THE GEOLOGICAL SOCIETY OF AMERICA 

 The twenty-first annual meeting of the Geolog- 

 ical Society of America was held under the presi- 

 dency of Professor Samuel Calvin, of Iowa City, 

 Iowa, in the rooms of the geological department, 

 Johns Hopkins University, Baltimore, Tuesday, 

 Wednesday and Thursday, December 29, 30 and 31, 

 1908. 



The first session of the meeting was called to 

 order at ten o'clock Tuesday morning with Presi- 

 dent Calvin in the chair and the society was 

 cordially welcomed to Baltimore by Professor W. 

 B. Clark in a few well-chosen remarks, to which 

 appropriate response was made by President 

 Calvin. 



The secretary. Dr. E. O. Hovey, of the American 

 Museum of Natural History, reported that the 

 printed list of fellows contained 294 names, the 



