Casella combined cup anemometer and wind vane

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This most attractive, cased wind measuring instrument was auctioned in 2014 on eBay(UK).

However, the seller was not open to bids from outside the UK. It sold on a single bid.

I have borrowed the excellent auction images for non-profit, educational use.

Parts of the wind vane show slight weathering which has produced a delightful, natural patina. Leading one to suppose that the unpainted finish is totally original. There is no sign of the typical, overall, grey paint used for permanently mounted meteorological instruments having been removed. In fact there is slight corrosion typical of copper around the anemometer cups. This is only likely to be cosmetic and can be easily cleaned off if desired. In the absence of professional clock cleaning fluids, ammonia, soft soap and water will do.


Note how well every item has its own location and protection against movement within the quality [mahogany?] carrying case. Such a travel case provides ready clues to the replacement and checking that all parts have been safely rehoused following dismantling after use in the field. The loss of a single item would probably make the device useless in the absence of spares. Though I note a rather large object is missing in the front, right corner space. Mounting blocks are fitted there but the space is vacant. The space available looks identical to that of the flange space alongside.

The instrument is provided with hooked, steel, ground pegs, guy lines with tension toggles and a flange-mounted stub mast. This suggests that the instrument was designed to be portable and for temporary erection only. Perhaps for use by expeditions. One can but guess as to the base upon which the mounting flange would rest in use. A handy tree stump, pipe or a sturdy tripod perhaps?


The bare, copper cups of the anemometer must have been most attractive turning brightly in the sunshine. The bronze casing of the head looks deliberately well finished. Despite the overall bare metal finish, the entire construction follows normal practice for British met-office approved instruments. Usually provided by established companies like Casella and Munro. This particular instrument is from Casella and the anemometer parts look [almost] identical to my own Mk2.

The anemometer is of the mechanical counter type and measures in miles. An observer would note the number visible in the counter window. Then read the number again after a fixed period of time. Subtracting the first number from second would allow the measurement of the wind at that location. The counter window being arranged horizontally suggests that the instrument was not usually raised very far above the observer. Mast mounted instruments would probably have a downward facing window for easier reading. Though a horizontal window might well have been used where easy access was possible via fixed ladders.

The wind vane is also entirely mechanical, weight counterbalanced and rotates below the anemometer. Its pointing angle being read off the large, clear, supplied protractor. Which is graduated by battens in 10 degree steps. Longer battens at 30 degree steps and digits to indicate the 90 degree angles. Most common wind vanes use the compass points.

Click on any image for an enlargement.

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