Argentina DST blues

[Andy Lipscomb]

"One historical question... I find that all cities, up until 1894-10-31 refer to LMT (Lima Mean Time?)... but all have different offsets... 
after that and up until May 1920, all refer to CMT (Córdoba Mean Time) at a fixed -4:16:48 offset.

Which is the source for the LMT offsets?... 'cause I'm happily copying and pasting and for sure introducing errors in the past... not that I'm afraid of the butterfly effect, but I'd rather not introduce wronful data..."

LMT actually stands for Local Mean Time.  In other words, average solar time at that location. It can be computed from longitude--each degree of west longitude converts to four minutes behind UTC; otherwise put, a 15-degree longitude difference equals a one-hour LMT difference.