CREATE TABLE table_40494 ("Name" CLOB, "Built by HM Dockyard" CLOB, "Ordered" CLOB, "Laid down" CLOB, "Launched" CLOB)

What was launched and laid down in February 1819?
SELECT "Launched" FROM table_40494 WHERE "Laid down" = 'february 1819'
SELECT "Launched" FROM "table_40494" WHERE "Laid down" = 'february 1819'