118 
THE MARL DISTRICT OF VIRGINIA. 
backward, to give to both these bones a more up¬ 
right position. Its action is in common with and 
for the same purpose as the small breast muscle. 
q, shows the tendon of the long extending mus¬ 
cle of the arm. It is a very important one; it 
reaches from the upper angle and the back edge of 
the shoulder-blade to the point of the elbow and 
the inside of the arm. Its office is to extend the leg. 
At r, r, s, are three divisions of another extending 
muscle, whose office is the same as the long extend¬ 
ing one. It is called the short extensor. It springs 
from the shoulder-blade and the lower bone of the 
shoulder, and attaches itself to the point of the 
elbow by a very strong tendon. The upper r goes 
from the shoulder-blade to the point of the elbow; 
the lower r goes from the upper part of the lower 
bone of the shoulder to the elbow; and s goes from 
the inner part of the lower shoulder bone to the 
elbow. Lower r, and s, are very strong and short 
muscles. They are very powerful agents in ex¬ 
tending the leg. 
y, presents the external muscle for bending the 
arm. It arises from the lower shoulder bone and 
the inner and back part of the neck, passes across 
the lower shoulder bone obliquely, and round it, 
and inserts itself into the inner and upper side of 
the bone of the arm. 
The Lower Bone of the Shoulder .— This bone 
makes a joint with the shoulder-blade, and runs 
downward and backward from the point (which is 
at the joint) of the shoulder. It is a strong one; 
it has a large round head, inserted into the shallow 
cavity of the shoulder-blade. There is no joint in 
the body which allows more varied and extensive 
'hnotion than this. The lower bone has several 
branches or elevations (tubercles) on to which 
muscles attach themselves ; it has at its lower end 
two heads, between which the upper end of the 
large bone of the arm is inserted, making the elbow 
joint. This is a joint which must be strong and 
secure, and hence its peculiar formation. It only 
admits of backward and forward movement in a 
straight line, without side motion. It plays back¬ 
ward and forward in the bending and extension of 
the arm. Behind the elbow joint these two heads 
receive the elbow deep between them, to give more 
extensive action to the arm. The lower shoulder 
bone should be short; indeed, can hardly be too 
short. The shorter it is the further forward is the 
leg. When it is too long it is nearer the horizontal 
line, and the leg is thrown too far under the horse, 
and the shoulder-blade is made loo upright. In con¬ 
sequence the whole forehand is too heavy. 
We have described all the muscles of the shoul¬ 
der together, as the shoulder is commonly spoken 
of as a whole, and as the muscles are so intimately 
connected. 
THE MARL DISTRICT OF VIRGINIA. 
The Marl District of Virginia comprises that 
portion of the State which lies between the Chesa¬ 
peake Bay and the falls of the rivers that empty 
into it; but in many places it does not extend quite 
to either extreme. Nor is it confined to Virginia, 
but is found in all of that strip of country between 
the Atlantic Ocean and the falls of the rivers from 
the Potomac to the Gulf of Mexico. I shall confine 
my remarks to that section which lies in Virginia. 
It is found in the sides and bottoms of ravines, 
with which the land near the rivers, creeks, and 
branches is much broken. It is also found in the 
beds of branches , which are better known to your 
northern readers as brooks. In some places, it is 
found almost at the surface, and in others, at the 
depth of several feet, though rarely at a greater 
depth than four feet, except on the level and un¬ 
broken land, where it generally lies at least fifteen 
feet below the surface. It is composed of marine 
shells, of a great variety of shape and form, inter¬ 
mingled with silica, and sometimes slight traces of 
green sand and gypsum. The quality of the marl 
is governed by the kind and quantity of shells. 
Some do not readily decompose on exposure to the 
weather, and others entirely decompose on exposure 
to one or two rains ; and those kinds which readily 
decompose, are of course the most valuable, and for¬ 
tunately the most plenty. I think the kind known 
to geologists as the Chuma Congregata, are the 
principal ones, and comprise more than one-half of 
the marls of Virginia. The shells are nearly pure 
carbonate of lime ; and the marl, upon analysis, 
furnishes from thirty to eighty per cent, of that sub¬ 
stance, varying with the number of shells it con¬ 
tains. It is only within a few years that these 
marls have been used to any extent as fertilizers of 
the soil. A few individuals made experiments many 
years ago, with no apparent benefit, and it was given 
up as worthless, until Mr. Edmund Ruffin, of Prince 
George, commenced his experiments. 
Mr. Ruffin had a large quantity of land, which 
by long and severe cropping had become like the 
rest of Eastern Virginia, so poor that it hardly paid 
in its returns the cost of cultivation. After many 
fruitless endeavors to sell his plantation, and re¬ 
move to the fertile lands of the southwest, he turned 
his attention to the rich marl deposites with which 
his land abounded. Knowing that lime was one of 
the principal ingredients in the marls, he also 
knew that lime was essential to the growth of all 
kinds of agricultural productions, and its applica¬ 
tion was generally recommended by the best scien¬ 
tific and practical farmers on both sides of the At¬ 
lantic ; he further ascertained by analysis, that his 
soil was almost entirely destitute of calcareous mat¬ 
ter. All of these facts satisfied him that the marl 
was valuable, and would prove beneficial. He ap¬ 
plied it in different quantities and on different soils, 
on nearly every one of which it proved highly bene¬ 
ficial. He continued its use some years very suc¬ 
cessfully. In the meantime, he procured and ana¬ 
lysed soils from different portions of the state, ami 
he found them almost entirely destitute of calca¬ 
reous matter; and he found, by experiment and in¬ 
quiry, among his brother farmers, that with the ex¬ 
ception of the rich river bottoms, the land upon 
some of the rivers where the Indians had for centu¬ 
ries been depositing oyster shells, that no perma¬ 
nent improvement could be made without the aid of 
calcareous matter. Clover, which before would 
hardly grow at all, without a heavy dressing of pu¬ 
trescent manures, grew luxuriantly upon the appli¬ 
cation of marl; and one or two crops of clover fal¬ 
lowed in, not only produced fine crops of wheat, but 
materially altered the appearance of the soil, chang¬ 
ing it from a light-colored or greyish, to a dark 
brown, or chocolate color; it also made a perma- 
