EL in cursive letters - provisional proof used after 1852.
Perron - Inspection mark after 1811.
Spangled ELG in an oval - definitive proof post 1818. Post 1893 mark is usually crowned.
Crown over lower case letters - the bench test controller's (inspector's) personal marks used 1853-1877. After 1877, the inspector's mark was usually a star over a capital letter.