Weather Stations – those imposing combinations of clocks, aneroid barometers and barographs – are days of work on the bench. On Saturday 19 July I took the plunge and, a week later, the principal is more or less completed. The clock is with my horologist although I have overhauled these movements before.
This is, for want of a better description, the ‘small’ Weather Station and is, so far as I know, unique to Negretti & Zambra, designed by or for them and, with the same certainty, made by or for them. Most of the larger Weather Stations were ‘white labelled’ and appear with names such as Hicks, Steward, Casella, Chadburn and others, as well as Negretti & Zambra.
Though Weather Stations are all very similar in style and execution, there are differences. I won’t go into details here – perhaps another time – but one interesting fact is that the barometers all appear to be made by William Callaghan. Indeed, it is possible that Callaghan supplied the barometer movement I’m working on but, unlike other Callaghan movements, this bears no identifying marks, possibly because there is no cock integral with the movement.
This Negretti & Zambra weather station is a different conversation to its larger iteration. Apart from the smaller size – only around 16” wide as opposed to 25” – mechanically it has some differences, with a design that is possibly unique to this maker. It will be appreciated from the images that the barometer, massive in proportion with its twin 5” diameter by 0.4” thick soldered capsules, is only possible because of the portion cleverly housed in the base of the instrument, the signal transmitted to the pointer’s arbor by a fine chain. This arrangement is the early design – later instruments included the barometer movement behind the associated dial.
It is worth pointing out that Weather Stations generally do not work very well, or even at all, unless they have been properly serviced and set up, as the mechanical demands placed upon the clock movement marginalise its available energy. Inherent in the design is the requirement for the clock to run itself, turn the recording drum, rotate the marker rail, and, in many, cock and release a hammer that strikes the barometer movement.
The same flaw blights the barometer which has, apart from driving the pointer around the dial, to move the marker carriage up and down the vertical guide. Aneroid designs all share a common issue of limited energy and static friction. Since the instrument is essentially a mechanical amplifier, the signal that starts as a very small deflection at the head of the capsule(s), when amplified by levers, causes a much larger deflection at the pointer. As we all appreciate, the laws of levers determines that a larger deflection is translated into less energy, which in turn can lead to a muted response at the reading end of the instrument. That is why the barometer movements in these instruments are so massive, or include multiple capsules, or both.
These smaller Weather Stations are extremely hard to find – far fewer made than the more widely known and much larger examples. So is it better, the same, or worse than its larger cousin? The smaller size and perhaps the aesthetic value definitely place this as a much more appealing option. From a mechanical perspective, the lower mass of the drum probably reduces the load on the clock driving it, which has to be a plus. The drum is also secured at the top with a hinged lid, a feature probably designed to reflect the much smaller diameter of the drum and therefore its reduced stability. The clock should get a mention – nice quality with a single fusee and deadbeat escapement.
The work on this instrument has included a full strip-down, a great deal of painstaking conservation, mechanical correction setting up, and of course final calibration. Has the effort been worthwhile? Definitely! Over time I have seen just three of these smaller Weather Stations, including this one – I have worked on all three!
