Focal plane in ft (m) is 43ft (13.1m) is the first date lit.
create table table_25597136_1 (date_first_lit varchar, focal_plane_in_ft__m_ varchar, PRIMARY KEY (date_first_lit))
select date_first_lit from table_25597136_1 where focal_plane_in_ft__m_ = "43ft (13.1m)"