A gadroon or godroon is a moulding composed of a series of convex flutes and curves joined to form a decorative pattern, used especially as an edge to silver articles. Research Gadroon
Cellulose is the cellular tissue of plants. It is a member of the carbohydrate family and is allied to starch. In plants, cellulose is normally combined with woody, fatty, or gummy substances. With some exceptions among insects, true cellulose is not found in animal tissues. Microorganisms in the digestive tracts of herbivorous animals break down the cellulose into products that can then be absorbed.
Cellulose is insoluble in all ordinary solvents and may be readily separated from the other constituents of plants. Depending on its concentration, sulphuric acid acts on cellulose to produce glucose, soluble starch, or amyloid; the last is a form of starch used for the coating of parchment paper. When cellulose is treated with an alkali and then exposed to the fumes of carbon disulphide, the solution yields films and threads. Rayon and cellophane are cellulose regenerated from such solutions.
Cellulose acetates are spun into fine filaments for the manufacture of some fabrics and are also used for photographic safety film, as a substitute for glass, for the manufacture of safety glass, and as a moulding material. Cellulose ethers are used in paper sizings, adhesives, soaps, and synthetic resins. With mixtures of nitric and sulphuric acids, cellulose forms a series of flammable and explosive compounds known as cellulose nitrates, or nitrocelluloses. Pyroxylin, also called collodion cotton, is a nitrate used in various lacquers and plastics; another, collodion, is used in medicine, photography, and the manufacture of artificial leather and some lacquers. A third nitrate, guncotton, is a high explosive. Research Cellulose
A shavehook is a decorator's tool used in burning off, especially designed for removing paint from mouldings. The shavehook is used with a pulling motion and as such is less liable to damage the contours of the moulding. Typically a shavehook has a triangular-shaped head, but pear-shaped and combination headed shavehooks are also made. Research Shavehook
A spectroscope is a mechanical device for analysing light. The Spectroscope resolves light into vibrations of different frequencies, so that its properties can be defined. Spectroscopes are used for such things as measuring the velocity of stars, looking at the rotation of the sun and the detection of chemical elements.
Mechanical spectroscopes generally included a slit and a collimator to admit the light in a parallel beam, and a viewing telescope. The Littrow type combines collimator and telescope, making the beam pass twice through the same lens. With a camera replacing the eyepiece, the instrument becomes a spectrograph, and when equipped with measuring scales and circles, a spectrometer.
The actual analysis is effected in refracting spectroscopes by one or more prisms of glass, or other refracting medium, which, by causing rays of shorter wave-lengths to deviate more than longer ones, splits up the beam into a rainbowspectrum with the red rays nearest the thin edge of the prism. As the dispersion increases with diminishing wave-length, the violet end is spread out more than the red, and the dispersion is called irrational. Small direct-vision instruments are made with an odd number of prisms in one tube, the even numbers reversed and of denser glass, so that for some mean ray the deviations cancel each other, the instrument being used pointing directly towards the light.
For some astronomical purposes the collimator is unnecessary, and the prism can be fixed outside the objectglass of a telescope (known as an objective prism). For very refined measurements the resolving power of a prism is insufficient and a diffraction grating was used. Fraunhofer first tried an actual grating of fine silver wire, and afterwards an optical grating of parallel lines rules by a diamond on a glass plate. Later, silvered glass was used for reflection instead of transmission, and then speculum metal replaced the glass.
Diffraction spectra are formed in sets, first, second, third order etc, on each side of the directly reflected rays, with the violet end nearest the central undisturbed image. An idea of them may obtained by looking at the sun through a feather. Ruled gratings being very expensive, cheap replicas, called Thorp gratings, were made by moulding melted celluloid on a ruled grating. Rowland's concave grating acts as its own condenser and focusing lens, thus avoiding the loss of light due to absorption. It yields a perfectly normal spectrum when used in certain positions.
Resolving power is the ratio of the wave-length to the smallest difference of wave-length actually separated by the instrument. With a very narrow slit it nearly equals the number of lines in the whole grating multiplied by the order of spectrum considered. Michelson produced a grating with a resolving power of 300,000. He also invented a new form of optical grating called an echelon, comprised of glass plates of uniform thickness being arranged in steps. Higher resolving power is reached by interferometers, especially Michelson's. In these the analysis is produced by passing the ray between parallel plates of glass, one or both only partially silvered, the phase of emergent rays varying with the number of internal reflections. Research Spectroscope
Cheshire is a British, traditional farmhouse hard cheese made from un-pasteurised cow's milk. Cheshire has a natural rind with grey moulding and the cheese is tightly wrapped in cloth. Very few farms produce real Cheshire cheese, most of it being mass produced in factories to the demands of supermarkets. Research Cheshire
In architecture an archivolt is the architectural member surrounding the curved opening of an arch, corresponding to the architrave in the case of a square opening. The term is also used to describe the moulding or other ornaments with which the wall face of the voussoirs of an arch is charged. Research Archivolt
In architecture the term astragal refers to a convex moulding of a rounded surface, generally from half to three quarters of a circle. Research Astragal
In architecture, a bague is the annular moulding or group of mouldings dividing a long shaft or clustered column into two or more parts. Research Bague
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Gadroon
