CREATE TABLE table_200_47 (id DECIMAL, "date" TEXT, "event" TEXT, "duration\ \ ( months ) " TEXT, "duration\ \ \ ( years ) " TEXT)

when did the first drop in the experiment fall ?
SELECT "date" FROM table_200_47 WHERE "event" = '1st drop fell'
SELECT "date" FROM "table_200_47" WHERE "event" = '1st drop fell'