Sorry about the poor pictures. 1870 in not bad shape cleaned on obverse. 1871 in really bad shape weighs 2.7 grams it's so worn but both appear to be Shallow N? Can you tell by these pictures?
From the pictures the first looks shallow and the second looks bold. Just my opinion on what my old eyes see.
Found this good site. 1870 is Shallow N and 1871 isn't. http://www.coincommunity.com/forum/topic.asp?ARCHIVE=true&TOPIC_ID=36985