Solution to #3: Putney
Special thanks to Abhinav Ramakrishnan.
The puzzle is a simple substitution cipher, which decodes to:
I ONCE THOUGHT THIS NUMBER WAS RATHER DULL
BUT NOW I FIND IT VERY INTERESTING
BECAUSE A FRIEND OF MINE INFORMED ME THAT IT IS THE SMALLEST NUMBER
EXPRESSIBLE AS THE SUM OF TWO CUBES IN TWO DIFFERENT WAYS
(key=JECVMSRXKADILBUTPOQHWNYFZG)
This is a description of the taxicab number, 1729.
1729