I should exceedingly rejoice that y 0n s 
hypothesis, if just, could be confirmed’1 
either by penetrating the outer crust quite 
through, or by exploring the supposed 
apertures within the arctic and antarctic 
circles of the globe. Then you would be¬ 
come one of the most profound theorists’ 
that ever addressed a wondering people. 
For the present you must rely upon the' 
analogies and probabilities you have sta- 
•edi 1 o those I have expected you to add 
more. 
*n the economy cf nature the long and' 
strong bones of the limbs are hollow; that 
i9 » l hey are not solid bone : the like is 
*rue oi the skull,- which is unsolid, and ca- 
pacious diat it may Contain the encepha- 
ian, or aggregation of all t he nerves. Are 
the veins and arteries hollow ? It is for the 
purpose of containing and conveying blood. 
Are the absorbent vessels hollow ? They 
imbibe lymph and chyle. Why are the 
stomach and intestines hollow? To receive 
food and to convert it into nourishment. 
And for what purpose are the windpipe 
and its ramifications hollow? what, but t© 
allow azote and perhaps other matters to 
enter the circulating mass, and carbon and 
other substances to escape. 
The feathers of birds are the most re¬ 
markable examples that I recollect of 
hollowness, combined with strength and 
the saving of stuff. The pith passing thro’ 
the barrel, like an axis, carries the vital 
fluid from one end of the cylinder to the 
other, from the wing to the plume. 
Among mineral bodies, hollow bodies, 
called geadcs, frequently occur. They con¬ 
sist, usually, of a number of concentric 
large circles, forming a crust or legmen, 
the inner surface of which is beautifully 
studded with crystals. In my cabinet there 
are several such, lined with splendid ame¬ 
thysts Sometimes there are loose nodules 
within them. 
Eggs, now and then, contain other eggs, 
exhibiting a shell within a shell. One of 
my neighbors, a few months ago, bought I 
a small hen’s egg, that was found in the 
g of a large one, but no bigger than 
t iG common size. Since that I have be- 
