Two instruments have been added to the Collection: an American pendant thermometer of about 1910–1920, worn on a neck chain, and a German pocket baroscope of about 1900 with a rotating differential pressure scale for which no analogue has yet been found.
The Pendant Thermometer with Bloodstone is a small novelty from an anonymous American workshop, assembled from a bought-in bimetallic movement and bought-in findings. Its round case hangs from a rigid bail and is finished on both faces: a Fahrenheit dial on one side, a polished bloodstone on the other, so that in wear it turns to show each in turn. Modest as it is, the pendant belongs to a largely forgotten fashion of the turn of the century, when thermometers, compasses and miniature aneroids were hung from the chain beside seals and lockets — a way of declaring one's allegiance to the age of measurement.
The is more of a puzzle. Beneath the flat bevelled glass of a barrel-shaped brass case lies an ordinary absolute scale of 66–80 cm Hg, but the rotating bezel carries a ring etched . Set NORMAL against any reading you please — the conventional 760 mmHg, the normal pressure for your own altitude, or simply the pressure at the start of an observation — and the single blued pointer reads both the pressure and its departure from that norm. Where almost every other pocket aneroid puts an altitude scale for the traveller, this maker put an anomaly scale for the weather-watcher, and named the instrument accordingly: the dial reads , not Barometer. Neither the reference literature nor the museum collections nor the market have so far yielded a second example.
