Are Victorian barometers mercury or aneroid?

Overwhelmingly aneroid. The word appears in 181 titles against 19 for mercury, so the sealed-capsule instrument is what dominates this heading. Mercury does turn up, in stick barometers and a smaller run of wheel barometers, and those cluster toward the top of the range.

What wood are the cases made from?

Oak is the defining timber, named in a quarter of all titles, with walnut second and rosewood and mahogany trailing well behind. Carving is the usual treatment, with 134 titles calling it out and 71 specifically carved oak. Polished oak accounts for another 59.

What does 'marine' mean in these listings?

It's dealer shorthand for the shipboard types, whether flat-backed bulkhead, gimballed or plain brass-cased. Marine appears in 181 titles, bulkhead in 45. Cases in this group are brass, bronze or steel rather than timber, and rope-twist bezels show up in 17 titles.

How accurate are the dates given?

Treat a stated decade as the dealer's estimate. Of 1,052 listings, 401 say only "Victorian" and 35 say "19th Century". Where a year is given, the weight falls late in the reign: 198 in the 1880s and 190 in the 1890s, against 62 in the 1870s and around 40 each in the 1860s and 1850s. A tail of 48 runs into the 1900s, with a few Edwardian and 1920s pieces carrying over.

What is an Admiral Fitzroy barometer?

A tall glazed storm barometer with a mercury tube and printed forecasting remarks across the backboard. It appears in 29 titles, with 'Polytechnic' and 'Royal Polytechnic' variants among them. It forms a small part of the category, well behind the carved wall aneroids.

Do unusual forms come up in this category?

They do. The samples include a barometer hatstand, a barometer paperweight, a caduceus-shaped clock and barometer, a hypsometer and a town hall barometer. Origins outside Britain are thin on the ground: a Danish carved walnut piece, an American one, a French 'Atmos', a few Black Forest carvings and a New Zealand pocket barometer. Sixty-nine dealers have listed in this category on Sellingantiques, and about 97 pieces reach the market in a year.