sup at Philips's Haverstock Hill with M(arshall) [N N] 15.9.1803
I've racked my brains with this N N. Robert Watt's Bibliotheca Britannica vols 3 & 4 (1824) had book titles and subjects in alphabetical order, which gave me New Nomenclature, which referred to the post Lavoisier chemical names. A translation of Dumas came out in 1801 and one of Hassenfratz in 1807. James Marshall certainly undertook translation work, so this is one possible suggestion for N N