Perched in a tower atop a hill, Matthew Douglas climbs a staircase and emerges from a hatch on the roof, where a heavy glass ball in a metal cradle has burned a thin streak into a strip of paper, recording the previous day's sunlight.
It’s part of a routine he and other weather observers at Blue Hill Observatory and Science Center, a weather station 15 miles (24 kilometers) south of Boston, have followed every day for the last 141 years. Using largely unchanged analog tools, they have built a continuous record of temperature, humidity, precipitation, wind and other measurements that can feed weather forecasts and scientific research.
