SCAGLIOLA. In Architecture, a com position , sometimes called also Mischia, from the mixture of colors employed in it, being made to imitate 'Warble. The Florentines claim the invention of this art, but it had been practised in Loin , bardy previous to its introduction at Florence. Lanza says that it was invented by Guido Sassi, who died in 1649, at the age of 65, at Carpis, in the state of Mo . dena, and that be commenced by exe cuting cornices and other members of ar chitecture which had all the appearance of the finest marbles ; whereas its intro duction at Florence was not till the raid ' die of the 18th century. Scagliola is j composed of gypsum or sulphate of lime, calcined and reduced to a fine powder, with the addition of which-to water a fine paste is made. When columns arc made with this composition, a frame or cradle is first formed, which is lathed round and coated with lime and hair, raised up in some parts with small projections. On this, when dry, is laid a composition consisting of pure gypsum, calcined and passed through a sieve, and, as wanted, mixed with glue or isinglass ; it is float ed with wooden moulds of the proper form, during which operation the colors, by which the imitation is obtained, are put on. When this is set the work is
smoothed with pumice-stone with one baud of the workman, while the other is employed in washing it with a sponge and water. It is then polished with trip oli, charcoal, and a piece of fine linen, and afterwards with a piece of felt dipped in oil of tripoli, and finished off with pure oil laid on with cotton wool. SCALE. In mensuration, a line or rule of a definite length, divided into a given number of equal parts, and used for the purpose of measuring other linear mag nitudes. It becomes a standard scale when all its divisions have been exam ined and compared with some standard measure. The scales of thermometers are graduated from some arbitrary point or zero (as that which indicates the tem perature of freezing water), from which the heat is counted upwards or down wards in degrees, which are also arbi trary.
The term scale is also applied to a mathe matical instrument, consisting of an as semblage of lines and figures engraved on a plane rule, by means of which cer tain proportional quantities or arithmeti cal results are obtained by inspection. Of these the principal are the plane scale, the diagonal scale, Gunter's scale, &c.