Mark has recently enhanced his test equipment and is now able to film barometers under pressurised conditions. This short clip shows the unusual Casella pocket barometer, made for the Royal Geographical Society c1930, replicating the effect of descending from 25,000ft to 12,000ft – and it only takes 27 seconds!



For more information about the RGS pocket barometer, click the image below:

Image of Royal Geographical Society Pocket Altimeter No 59 by Casella