The data collected from tree rings is incredibly noisy. An initial exponential decay function is typically used to smooth out the age related decline in tree growth (that is younger trees put on more girth per unit stem diameter in a year than older trees). Then any number of different functions can be used, from sin waves to moving averages, to further smooth the data and removed stand dynamics, species and local site variations.

There is an unusual amount of subjectivity involved in the process.

Be that as it may, there is a strong correlation between tree ring chronologies and past climate up until the 1960's-1970's (that is past climate from direct measurements but also other proxy data) when the two diverged and tree rings no longer served as a reliable proxy.

This divergence can be for any number of factors from a change in precipitation patterns, lowered water tables or even a change in wind direction/velocity.

So it certainly seems that they are acurate for a period of the temperature record but the divergence should be a great cause for concern and should cast a speculative eye on older data that lacks a true (not proxy) temperature record to compare to.

Best book I have found is Programming C# 3.0 by O'Reilly Press. The company releases a lot of books used in the industry for operating systems, networking, scripting, programming languages, etc.

Here is the amazon URL for it

ISBN-10: 0596527438

PHP will help you do anything like that. If you can't use PHP then you should learn it.

last emergancy airdrop i got i got a uav 2 counters and a resuply