FitzRoy and his Barometers - Philip R. Collins Books on Antique Stick Barometers The glow or plasma is

The glow or plasma is created by applying voltage and the requisite pressure within each will denote how strongly or brightly the tube glows

the exposed barometer tube runs centrally down the full length of the instrument with half globe mahogany cistern cover to the base and cistern adjustment screw below

weighted brass is contrived to unscrew from the upper platform with the catalogue images suggesting that it may have had an auxiliary screw to allow for field attachment

This latter function would of course lead to greater efficiency for the engine overall and is seldom seen on most extant model examples

FitzRoy and his Barometers - Philip R. Collins Books on Antique Stick Barometers The glow or plasma isTravelling around Cape Horn in stormy weather, the Beagle went under water twice, bobbing up like a barrel, but each time taking on more water; if the Beagle had gone under a third time, it was believed she would have sunk, no doubt with the loss of all life. Her captain, Robert FitzRoy, blamed himself for this near calamity, having not taken enough notice of the falling barometer. He never forgot this incident and became a firm believer in the value