Cw0909 already gave you the link to best website about antique padlocks. You asked about time-dating the "lever" padlock you found. Unmarked one are difficult to narrowly time-date. An important ID-&-time clue on yours is that its keyhole is shaped like a number 9. Based on others I've seen with that characteristic, yours dates from the latter-1800s through early-1900s. But I'm not even nearly an expert on antique padlocks. I suggest you contact the owner of the antique padlocks website.