200-Year-Old Encryption Method

I read this article about a 200-year-old encryption method that was finally cracked by a mathematics professor. It's amazing how he found the method to decrypt it. What's more amazing is it took 200 years for someone to decrypt it.

Now that the method is out, I made my own encrypted message. Read the article, understand the method, and decipher the code below. As a clue, this message is the lyrics to the most well-recognized song in the English language (according to the 1998 Guinness Book of World Records).

pyaturahurybhtpayar
yopaahurpdbtodpusbr
hadpipdhtoiahyyyhpa
barsopyuyhtoioyyrpd
ordtbabtpaahyyrypdy
oprybtpaiahuarhbpdt
ihyabioyypdbhtoyard
tparyohdyyypdhtpaio

Cipher Key: 26, 42, 35, 19

Have fun! :)