Today I added a Dingens Eco-celli E038 tendency barometer to the instrument collection on the website. It's a clever device that uses Boyle's law and an automatically temperature-corrected pressure scale to measure sea level pressure.  Designed in 1998, it's intended to be a mercury-free school barometer, not an observatory barometer.  However it's also an attractive and affordable instrument for home use.

​See Eco-celli tendency barometer.