For sale, a large demonstration gyroscope on stand by Negretti & Zambra of London.
This solid brass gyroscope is held in a U shaped frame from which a circular mount is attached. The mount holds the central rotor disc which is attached by a spin axis to the top and bottom and can be spun to high resolution by means of winding a string around the axis which is threaded through a small hole in the axis.
The U shaped frame has a shaft which sits freely in a solid brass base on which the maker’s name is engraved, “Negretti & Zambra, Instrument Makers to Her Majesty. London”.
The name gyroscope was coined by the French scientist, Leon Foucault in 1852 as a result of his investigations into the rotation of the earth and the development of the ideas of the German scientist Johann Gottlieb Bohnenberger from 1817. The experiment was commonly used thereafter to show how a spinning rotor resists changes to its orientation due to the angular momentum of the wheel. A phenomenon also known as gyroscopic inertia or rigidity in space, gyroscopes have been central to development of navigational instruments.
Negretti & Zambra were a leading name in the production of meteorological and scientific instruments and had a company history dating back to 1850 although their parents were amongst those Italian emigres that bolstered the British meteorological instrument making industry at the turn of the century.
Throughout their long and esteemed history they exhibited at British and international industrial fairs and became makers to both Queen Victoria and Edward VII. Owing to changes in the business, the firm ceased the public retailing of scientific instruments sometime around the late 1960’s and continued with a focus on the aviation industry in numerous guises until its eventual liquidation in the year 2000. They are today perhaps the most collected of the scientific instrument firms which bears testament to the quality of their work.
The company produced demonstration gyroscopes throughout their trading life and their encyclopaedic catalogue of the 1880’s contains an example which is described:
“The Gyrocope – a modification of Bohnenberger’s machine introduced by M Foucault, is an instrument arranged to illustrate the following principles:
That inertia is a property of matter in motion, as well as of matter at rest.
That orbital and axial motion are intimately related, and that the speed of one may affect or regulate the other.
That the state of unstable equilibrium in which many bodies remain is to be explained by the fact of their rotation.
That bodies in motion endeavour to maintain their original plane of rotation.
That the power of resisting or overcoming the force of gravity possessed by shots fired from Armstrong’s gun is due to the gyratory motion given to them by the peculiar formation of the gun.
It will also illustrate the precession of the equinox”.
This fine instrument is an early example of their work. The italic engraving is of the type that the company used throughout the 1850’s and 60’s and very unlike the wording used in the catalogue example.