An early Victorian rosewood stick barometer with double Vernier and bone float by JB&J Ronchetti of Manchester.
This rare instrument is constructed of quality rosewood with a square moulded pediment above a “v” sectioned scale plate with gothic style engraving reflecting three weather indications, “Fair, Change & Rain” and showing 27 to 31 degrees of barometric pressure. Above is engraved the maker’s name of “JB & J Ronchetti - Manchester” and to the base each side is marked, “yesterday 9am & today 9am” respectively. This feature allows for the left hand Vernier to be set on a certain day and the right hand Vernier to be set on the other side at the following day’s reading. Thus it allows the owner to keep an accurate record of the ongoing changes to the weather.
Below the glass fronted scale plate are two bone knobs which operate the Vernier markers (both replacements) and below them is a removable thermometer with silvered scale showing readings for both Fahrenheit & Reaumur. The rosewood cased and glazed fronted thermometer was intended to be removable to allow the user to measure temperature in different areas of the household as required.
The base of the barometer has an urn shapes cistern cover with its original bone float. These floats are a seldom encountered feature on stick barometers and only found on the highest quality examples. Thought to have been invented by the famous instrument maker, Jesse Ramsden, the float was considered to be a solution to eliminating errors in the cistern level of the barometer and to zero balance the scale for correct reading.
The brother makers John Baptist & Joshua Ronchetti were third generation Italian immigrants whose family settled in Manchester in the late eighteenth century and began to trade as scientific instrument makers. Originally living in Tavernerio in Italy, they were one of numerous Italian families that moved to England during the period.
The brothers took over their father’s business (Charles Joshua) in the late 1830’s after he went on to set up a weather proofing factory in the Clayton area of Manchester. The brothers according to a notice in The London Gazette had previously formed a partnership which was dissolved in 1837 and had been trading from the centre of scientific instrument making in London during the period at No. 2 Hatton Gardens, very close to where Negretti & Zambra would open for business thirteen years later. It suggests that the offer of their father’s business at 43 Market Street, Manchester was a better opportunity than their dealings in London and they continued in business until 1851 whereafter it is thought that they then took over the weather proofing factory. The business was finally sold to their brother in law Joseph Casartelli but during their brief period of trading in Manchester, the brothers produced some exquisite scientific instruments which can all be dated to the very early part of Queen Victoria’s reign. This is a superior quality instrument dating to circa 1840.