232 
SCIENCE. 
The path along which they walk is a path which they did 
not engineer. It is a path made for them, and they simply 
follow it. But the propensities and tastes and feelings 
which make them follow it, and the rightness of its direc- 
tion towards the ends to be obtained, do constitute a unity 
of adjustment which binds together the whole world of 
Life, and the whole inorganic world on which living things 
depend. 
I have called this adjustment mechanical, and so, in the 
strictest sense, it is. We must take care, however, not to 
let our conceptions of the realities of Nature be rendered 
indistinct by those elements of metaphor which abound in 
language. These elements, indeed, when kept in their 
proper places, are not only the indispensable auxiliaries of 
thought, but they represent those perceptions of the mind 
which are the highest and the most absolutely true. Th> y 
are the recognition — often the unconscious recognition- -of 
the central unities of Nature. Nevertheless, they are the 
prolific source of error when not closely watched. Because 
all the functions and phenomena of Life appear to be strictly 
connected with an apparatus, and may therefore be regarded 
as brought about by adjustments which are mechanical, 
therefore it has been concluded that those phenomena, even 
the most purely mental, are mechanical in the same sense 
in which the work is called mechanical which human ma- 
chines perform. Are not all animals “automata?” Are 
they not “ mere machines?” This question has been re- 
vived from age to age since philosophy began, and has been 
discussed in our own time with all the aid which the most 
recent physiological experiment can afford. It is a question 
of extreme interest in its bearing on our present subject. 
The sense in which, and the degree to which, all mental 
phenomena are founded on, and are the result of mechani- 
cal adjustments, is a question of the highest interest and 
importance. The phenomena of instinct, as exhibited in 
the lower animals, are undoubtedly the field of observation 
in which the solution of this question may' best be found, 
and I cannot better explain the aspect in which it presents 
itself to me, than by discussing it in connection with certain 
exhibitions of animal instinct which I had occasion to ob- 
serve during the spring and summer of 1874. They were 
not uncommon cases. On the contrary, they were of a kind 
of which the whole world is full. But not the less directly 
did they suggest all the problems under discussion, and not 
the less forcibly did they strike me with the admiration and 
the wonder which no familiarity can exhaust. 
IMPROVEMENT OF THE MISSISSIPPI RIVER.* 
By Prof. W. H. Ballou. 
The Mississippi River is the most gigantic parasite 
known to men. The least possible estimate, computed 
from data in hand, shows that the annual average for the last 
thirty years, of money exprnded cn it for improvements, 
and lost through its depredations, exceeds $7,000,000. 
Fully one-third of this sum is used by the government, 
States and private individuals to keep the stream and its 
tributaries in an “improved condition.” The table will 
show the average of the expenditures obtained for the last 
thirty years : 
Expenditures of the States of Mississippi, Louisiana and 
Arkansas on levees since 1840 $100,090,000 
Expended by 'he government and private individuals — 
estimate 50,000,000 
Damage by floods, ice gorges, etc., to levees, property, life 
eic 80,000,000 
Total ... $230,090,000 
Average per annum, $7,669,666. 
To this may be added 26,772,379 acres of land granted to 
the above States by the government in 1849, the value 
being about $10 per acre 267,773,790 
Total $497,813,790 
Average per year, $16,000,000. 
Only those who are acquainted with the stream and its 
peculiarities have an idea how unmanageatle it is. The 
unstable condition of the soil of the country through which 
it flows renders it an object of distrust to the inhabitants of 
its border. Such is the treacherous condition of its rela- 
tions that for sixty-two years the ingenuity of man has con- 
trived no check on its action. The causes of this condition 
* Read before the A. A. A. S., Boston, 1880. 
of things are found partly in the river-bed. The sedimen- 
tary deposit varies from Co to too feet in depth. It is gen- 
erally composed of silt, with a mixture of clay and sand, 
which, having been deposited by the river, is at its disposal 
to lie still or be shifted about. It is evident that no ordi- 
nary construction can long stand unless it has a foundation 
penetrating this bed to a rock stratum. The great bridge 
at St. Louis, for instance, has its piers resting on the lime- 
stone bed-rock, under a sedimentary deposit of seventy 
feet. The railway bridge at the mouth of the Minnesota 
river has its piers lodged on a slender stratum of hard earth 
sixty feet beneath the river’s bottom. It is further admitted 
that in boring through this stratum a soft layer was struck, 
which would not uphold the rod’s weight. At Cairo, 111 ., 
in 1877, the United States corps of engineers, under Lieu- 
tenant D. W. Lockwood, made borings to a depth of 87 
feet without encountering any stratum harder than sand. 
At this point the machinery broke down and operations 
were suspended. At a depth of 33 feet the auger pene- 
trated a cottonwood log, hardly ready to decay, showing 
conclusively the facility with which the river makes its own 
bed. At the same place it is stated on good authority that 
piles, one on another, have been driven to a depth of 125 
feet without encountering a rocky stratum. 
The story of its great width is even more remarkable. 
Near Cairo, 111 ., the river moved a mile out of its course in 
one year, and is continually changing at that point. Still 
more remarkable are the operations of the Missouri river. 
At one time Council Bluffs enjoyed its presence in the im- 
mediate proximity, and the benefitsof itscommerce, in conse- 
quence of which the city became the terminus for Western rail- 
ways in preference to Omaha, three times its size. These rail- 
roads erected depots and stationed offices of general Western 
superintendents there. The Union Pacific constructed an 
immense bridge, and in common with other rail ways built a 
union depot at the Bluffs. No sooner was the work com- 
pleted, than the Missouri performed the rare feat of moving 
its course to Omaha, three miles away. There is no end to 
instances of this kind on a smaller scale. It may be safely 
asserted that from its narrowest point the Mississippi varies 
to twenty miles in width. It is no wonder, then, that the 
present embankment system is inadequate. Appropriations 
are only asked at present for embankments as far north as 
Cairo. It is evident, however, that the sedimentary bed ex- 
tended nearly to the source of the Mississippi, and that 
not only must the no miles from New Orleans to Cairo be 
embanked, but also the greater shore line above the latte 
city on both this river and the Missouri. An explanation 
of the frequent destruction of levees, dikes and embank- 
ments is found in the method of their construction. When 
the current leaves the middle and runs along one side of 
the stream, the bank is rapidly torn down. At this point 
the corps of engineers proceed to build a dike to resist the 
destructive force. A rip-rap is first constructed which con- 
sists of a raft covered with long poles, placed cross-wise in 
alternate layers. This is loaded with heavy stones and 
sunk near the shore. Outside of it long poles are driven 
to a depth of twenty or thirty feet, and sometimes to twice 
these depths. Brush and stones are heaped upon their 
foundation until a perpendicular embankment is completed 
on a level with the top of the bank. One would think that 
this ponderous dike would stand for ages. But so vaccil- 
lating is the silt bed underneath that the water keeps work- 
ing the outer edge .with powerful results. The embank- 
ment settles, sometimes toppling over, and again dropping 
suddenly from sight. Often the water works in behind 
these constructions and leaves them out in the stream. 
Thus it happens that the river is at work at innumerable 
points, tearing away its banks and defying the structures 
in use to hold it in check. 
In its work of destruction the current has some formid- 
able aids. In the winter ice floats down continually. So 
immense are these cakes at times that three, and even two 
coming down stream abreast will get caught on the sides of 
the river, in some narrow channel, and form a bridge. This 
bridge effectually holds back all oncoming ice. The great 
and small cakes coming down in large quantities join 
under, over and behind the bridge, piling up to a great 
height, forming a gigantic gorge. This mass finally breaks 
away ; no power yet inaugurated by the hand of man is able 
to withstand it. Embankments, boats, live stock, people, 
