In Marston's Scourge of Villanie, Satire IV, reference is made to some unnamed author as follows :
"Whose silent name one letter bounds."
So far as we know there is only one letter in the alphabet that applies to this description, and that is the letter C, because C is the Roman numeral for 100, which is the numerical count of the name Francis Bacon. It therefore follows that if we find the capital letter C placed in a book in such a position, that it is obvious that has not got there by accident, we see what represents the name "Francis Bacon."
In a little book entitled "Mercury: or The Secret and Swift Messenger," title paged to John Wilkens, on the first page of the address "To the Reader" it will be seen that the first letter on the middle line (which is the ninth line counting either up or down) is a capital C, and in the middle of this same line are the words A HUNDRED.
C represents a hundred, which is the numerical count of the same "Francis Bacon," and it would be difficult to find a neater way of signing the book in a secret manner.
SirBacon.org - Sir Francis Bacon's New Advancement of Learning