I have to wonder, how many weather stations did they have in the 1880's? Not as many as in 2010. And the methods for measuring temperature are much more accurate and standardized now than they were even in the 1950's. The data collected at the beginning is going off the bat be summarized, recorded and averaged differently.
How then can the data of yesteryear when records started to be kept really be considered that reliable in comparison to the data in 2010 in order to make a chart projecting climate change?
Let's say there were (hypothetically) 500 weather stations in 1880, and now there are 10,000 plus satellites, plus computers monitoring the weather. Would the averages taken now be different anyway by default, due to better accuracy?