It is very probable that after reading 
this account of Halley’s Theory, there 
will be found some so incredulous as to 
demand more proof than a protest on hon¬ 
or, before they will believe that Syrnmes 
did not copy it. Some will also say, that 
if he was ignorant in 1818, that the idea 
was Kepler’s or Halley’s, he is not igno¬ 
rant of the fact rnw ,* and that it is high 
time for him to quit talking of Symme’s 
Theory, or the, ‘progress of the Captain's 
Theory,’ and to say instead, Halley’s or 
Kepler’s Theory. 
He refers me to his second and third 
memoirs until he is able to spare the time 
to answer my arguments. I would rather 
be spared the unprofitable labor of com¬ 
batting unfounded assertions and extrava¬ 
gant guesses, which he is pleased to call 
| mathematical and occular demonstrations,. 
when the cause can be brought to a much 
speedier issue. I have endeavored to 
prove by two short arguments, the impos¬ 
sibility of the earth being hollow to the ex¬ 
tent he supposes. He calls these argu¬ 
ments weak . If so, they will be easily 
refuted; and I hope he will be able to 
spare time enough to do it. I promise to 
believe in his theory if he refutes either 
j one of them. The first is a very plain, 
1 but I think a very solid argument. The 
earth cannot be hollow, because it is so 
very heavy to its size . The other, is that 
no hollow shell of the size of the earth 
can exist, because there is no adequate 
force to prevent it from falling in. Capt. 
Symmcs may take his choice of them, or 
he may take both. He will observe that 
I use plain terms, because I wish to be un¬ 
derstood bv all. I). P. 
Note. —The editor of the Aurora, after pub¬ 
lishing mine of the 1st Sept, says in a note, that 
Syrnmes is mad. Mr. Duane must be mistaken, 
for I recollect to have seen a Certificate of san¬ 
ity, signed by some very respectable people in 
St. Louis, very properly accompanying the 
Captain’s first circular. 
[The following article, though intended 
to reply to the first strictures of D. P. 
replies also to the preceding, P* it 
is hoped, will abate somewhat of his as¬ 
perity, if he thinks proper to answer j 
1 this writer.] 
