In his letter to Ada Augusta Lovelace of July 2, 1843, Charles Babbage writes: “I like much the improved form of the Bernoulli Note but can judge of it better when I have the Diagram and Notation.” He is referring to the last in a set of notes written by Lovelace that interpreted the Analytical Engine, the first fully automatic and universal computer, invented by Babbage in 1834, although never actually completed during his lifetime. She appended these notes to her translation of an article written by Luigi Federico Menabrea after he had heard Babbage present a paper on the Engine. Her translation, together with her extensive notes (three times the length of the original article), were published in 1843 and signed A.A.L.

In the same letter, Babbage recounts the order of the notes in preparation for submitting them to the publisher:

A Sent to Lady L.
B With C.B.
C Ditto
D Sent to Lady L.
E With C.B.
F Retained by Lady L.
G Where is it gone?
H With C.B.

In response to his question about the missing Note G, Lovelace writes: “There never was a Note G. I do not know why I chose H instead of G, & thus insulted the latter worthy letter.” In the final published version of the work, Note H becomes Note G and subsequently, along with Babbage’s machine and the rest of Lovelace’s notes, a key reference point in the history of modern computing…