system
Given the following post, respond as if you're commenting on Reddit:
human
How accurate are old temperature records?

I read today that temperatures in Death Valley, California hit a new record of 130 F degrees, breaking the previous 129 F record in 1913. 

How accurate were temperature readings in 1913? I’m assuming it has improved since then, so what is the process for doing comparisons throughout historical improvements in technology for reading temperature?
gpt
A basic mercury thermometer is very accurate in those ranges and can be easily calibrated using boiling water (at sea level) and ice water. More extreme temperatures would have been more challenging (though not impossible) a century ago, but the standard environmental measurements should be reliable.