433 



noodod, and tluis obtain a nuicli Ixittcr liasij Cor jiid^mciit as to liow to diHtrilmtti liis 

 crops on his laud, as to what his yields wcro likely to bo and whetlier nictiiofls of 

 tillage intended to reduce or conserve the luoisture already iu the soil should 1)0 

 adopted. 



roniUon and attitude of the water-tahle.— To study the foregoing and allied questions 

 from the experimental side it seemed important to know at the outset the distance 

 from the surface of the cultivated fields and experimental plats to permanent water 

 in the grouiul at the university farm, and whether or not this water was drawn 

 upon, especially during dry seasons, by the crops growing upon the himl. The 

 invesitigatiou was begun in August, 1888, and has been continued since when time 

 permitted. 



With the aid of an 8-inch post auger, provided with an extension handle, four lines 

 of wells have been bored, three of them constituting north and south parallel series, 

 and the other crossing these at a right angle. » • * After taking the levels of 

 the several wells and of the water iu them, it was found that the water stands every- 

 where in the ground above the level of the water in the lake, and that the level of 

 the water-table rises where the ground rises aud falls where it falls, but not in such 

 a manner as to make the two surfaces parallel. For example, at a distance of I'M 

 feet back from the lake shore the water in the ground stands about 2 feet above the 

 lake level, but farther back the difierence of level is nearly 10 feet. » * » A study 

 in other yilaces shows that similar conditions exist elsewhere. » * * That this 

 attitude of the water-table is not due to simple capillary action iu the case, is proven 

 by the fact that water was not reached in the two central wells until a stratum of 

 green sand, 2 feet below the level of the lake, had been entered ; this being reached 

 the water rose slowly until it stood G inches above the lake level. 



Fluctuations in the level of the water-table. — To ascertain if possible whether vege- 

 tation is able to avail itself, through capillary action, of the penuanent ground water 

 and thus tide over seasons of drought, the variations in the level of the water iu the 

 ground have been measureil by means of an iustrumeut constructed for the purpose, 

 which is sufficiently sensitive to allow changes of level less than one hundredth of an 

 inch to be detected. More than six thousand measurements of the level of the water 

 in the wells of the four series have been made during the year, and as the water iu 

 these wells lies at ditferent distances below the surface, some of the wells being below 

 corn, others below oats, meadow, pasture, or woods, while others still stand in 

 ground which bore no crop, the surface being simply tilled to prevent the growth of 

 weeds, it was hoped that in case the permanent water in the ground was drawn upon 

 by vegetation to any notable extent the fact would be revealed by ditferences iu the 

 fluctuations of the water level iu the several wells. 



The fluctuations observed have been surprisingly marked, and so varied as to 

 indicate that several causes must be operating conjointly to produce them, but at this 

 stage of the investigation it is evident that a longer series of observations and a 

 more critical analysis of them than is now possible is required for a solution of the 

 problems involved. Among the facts which the present study have developed are 

 these : 



(1) There are, from May to October, daily fluctuations of the water level iu the 

 ground, the water either rising during the night or falling less than it did during the 

 day. 



(2) There are fluctuations extending over several days, during one portion of 

 Avhich the water falls at a rate faster than the average, while during the remainder 

 of the time it either makes a positive rise or else falls at a rate below the average. 



(:^) The diurnal fluctuations are very unequal iu magnitude, varying in different 

 wells from less than 0.01 or 0.02 of an inch to 1.7 inches. 



(4) The longer-interval fluctuations a,re not ixactly synchronous, there being a 

 lagging, with some wells, of more thau 24 hours. 



