The bridging stone between the obelisks has, on its front, "Arter's Block".
In the centre of this curious inscription is the square and compass symbol of the Freemasons. In 1857 Dr. Arter was a charter member of one of Cairo's two Masonic lodges. 1 The phrase "Arter's Block" was likely chosen for Masonic significance.
On the reverse of the "Arter's Block" stone is the letter "G", which in Freemasonry stands for "God".
The below portrait of Daniel Arter (with the "peculiar signature") appeared in William Perrin's 1883 History of Alexander, Union, and Pulaski Counties.
Daniel Arter and Milly Anne Moyer were married 8th December 1837.2
1.
Perrin, William Henry:
History of Alexander, Union, and Pulaski Counties, Illinois.
(1883) p.157