SCALZ, Gunter'8, an instrument, so call. ed from Mr. Gunter, its inventor, is gene rally made of box ; there are two sorts, the long Gunter, and the sliding Gunter, having both the same lines, but different ly used, the former with the compasses, the latter by sliding. The lines now gene rally delineated on those instruments are the following, wiz. a line of numbers, of sines, tangents, versed sines, sine of the rhumb, tangent of the rhumb, meridional parts, and equal parts ; which are con structed after the following manner : The line of numbers is no other than the logarithmic scale of proportionals, wherein the distance between each divi sion is equal to the number of mean pro portionals contained between the two terms, in such parts as the distance be tween 1 and 10 is 1000, &c. equal the lo garithm of that number. Hence it fol. lows, that if the number of equal parts expressed by the logarithm of any num ber be taken from the same scale of equal parts, and set off from 1 on the line of numbers, the division will represent the number answering to that logarithm. Thus, if you take .954, &c. (the loga rithms of 9) of the same parts, and set it off from 1 towards 10, you will have the division standing against the number 9. In like manner, if you set off .903, &c. .845, &c. .778, &c. (the logarithms of 8, 7, 6) of the same equal parts from 1 to wards 10, you will have the divisions an swering to the numbers 8, 7, 6. After the same manner may the whole line be con structed.
The line of numbers being thus con structed, if the numbers answering to the natural sines and tangents of any arch, in such parts as the radius is 10,000, &c. be found upon the line of numbers, right against them will stand the respective divisions answering to the respective arches, or, which is the same thing, if the distance between the centre and that di vision of the line of numbers, which ex presses the number answering to the na tural sine or tangent of any arch, be set off on its respective line from its centre towards the left hand, it will give the point answering to the sine or tangent of that arch : thus the natural sine of 30 de grees being 5,000, &c. if the distance be tween the centre of the line of numbers (which in this case is equal to 10,000, &c. equal the radius) and the division, on the same line representing 5,000, &c. be set off from the centre, or 90 degrees, on the line of sines, towards the left hand, it will give the point answering to the sine of 30 degrees. And after the same manner may the whole line of sines, tan gents, and versed sines, be divided.
The line of sines, tangents, and versed sines, being thus constructed, the line sine of the rhumb, and tangent of the rhumb, are easily divided ; for if the dc grees and minutes, answering to the angle which every rhumb makes with the meri dian, be transferred from its respective line to that which is to be divided, we shall have the several points required : thus, if the distance between the radius or centre and site of 45 degrees equals the fourth rhumb, be set off upon the line sine of the rhumb, we shall have the point answering to the sine of the fourth rhumb ; and after the same man ner may both these lines be constructed. The line of meridional parts is construct. ed from the table of meridional parts, in the same manner as the line of numbers is from the logarithms.
The lines being thus constructed, all problems relating to arithmetic, trigono metry, and their depending sciences, may be solved by the extent of the compasses only ; and, as all questions are reducible to proportions, the general rule is, to ex tend the compasses from the first term to the second, and the same extent of the compasses will reach from the third to the fourth ; which fourth term must be so continued as to be the thing re quired, which a little practice will render easy.
Scats, scala, in music, is a denomi. nation given to the arrangement of the six syllables invented by Guido Aretine, at, re, mi, fa, tot, la, called also gamut. It bears the name scale (q. d. ladder) because it represents a kind of ladder, by means whereof the voice rises to acute, or descends to grave ; each of six sylla bles being, as it were, one step of the ladder. Scale is also used for a series of sounds rising or falling towards acute ness or gravity, from any given pitch of tune, to the greatest distance that is fit or practicable, through such intermedi ate degrees as make the succession most agreeable and perfect, and in which we have all the harmonica! intervals most commodiously divided.
Scatss of fish, generally possess a silvery whiteness, and are composed of different lamina. In many of their pro. perties they' resemble horn. By long boiling in water they become soft, and when they are kept for some hours in nitric acid, they are converted into a transparent membranous substance. By saturating the acid with ammonia, a pre cipitate is formed, which is phosphate of lime. The constituent parts of scales, therefore, are membrane and phosphate of lime.