Locke
I think that it goes without saying that Fred M. Locke could very well be called the Father of porcelain insulators and there is so much history involving this man and his influence on porcelain manufacture, I don't feel I can do either justice in this short space.  I would recommend Mr. Elton Gish's biography of Fred Locke to anyone interested. I can assert that no insulator on this page will predate 1910-1920. 
U 286's
U 287
U 287A
Characteristics:

Color(s)
--- dark chocolate brown, chocolate brown, white, streaked grey/blue, dark grey, green over brown, streaked butterscotch, reddish brown, cobalt, light butterscotch, sky blue, dark brown with cream highlights, light grey

Pinhole(s)
--- about 50-50 partial or fully glazed

Pinhole Top(s)
--- plain to slight dome on some, flat penny sized indetation on others

Fire Rested
--- petticoats

Wet/Dry Processed
--- wet

Marking(s)
--- incised "LOCKE" on skirt, incised "LOCKE/44" on skirt, incised "LOCKE" on dome
U 292's