INCH 131 INCOME TAX the degrees wherein marriage is forbid- den by the law of the country. Spiritual incest is a term denoting the crime of sexual intercourse between persons spir- itually allied by baptism or confirmation. Also the act of a vicar or other benefici- ary who hold two benefices, the one de- pending on the collation of the other. INCH, a lineal measure, being the 12th part of a lineal foot, or the 36th part of a lineal yard. INCH, an island. It appears fre- quently as an element in the names of small islands belonging to Scotland; as, Inchcolni, etc. In Ireland it appears in the original form of Innis or Ennis. INCH CAPE. See Bell Rock. INCHCOLM (insh-kom'), a small is- land of Scotland, in the Firth of Forth, off the coast of Fifeshire, with the ruins of a monastery founded by Alexander I. in 1123, of which Walter Bower, the con- tinuator of Fordun, was abbot from 1418 till 1449. INCHKEITH (insh-keth'), a small island of Scotland, in the Firth of Forth, off the Fifeshire coast, containing a light- house. INCIDENCE, the manner of falling on, or the direction in which a body, or a ray of light, heat, etc., falls upon any surface. Angle of incidence, an angle formed by two straight lines, one the line of incidence of a ray of light or heat, or of an elastic body moving to strike a plane, and the other a perpendicular to that plane. The angle formed by the perpendicular and the line of departure taken by the elastic body is called the angle of reflection, and is always equal to the former one. Line of incidence, the straight line taken by a ray of light or heat, or an elastic body moving to strike a plane at an acute or right angle. INCLINATION, the mutual approach, tendency, or leaning of two bodies, lines, or planes toward each other, so as to make an angle where they meet, or where the lines of their direction meet. This angle is called the "angle of inclination." In pharmacy, the act by which a clear liquor is poured off from some faeces or sediment by only stooping the vessel ; also called decantation. INCLINED PLANE, one of the me- chanical powers. It consists of a plane, inclined obliquely to the horizon. The velocity acquired by a body descending an inclined plane is the same as if it had fallen perpendicularly from the same height. The inclined plane is used for the descent of bodies ; also for the ascent, by vehicles, etc., of hills far too steep; to be directly scaled by wheeled carriages. INCLINED STRATA, strata which dip at an angle with the horizon. INCOME TAX, a tax levied directly from income of every description, whether derived from land, capital, or in- dustry, first imposed in Great Britain in January, 1799, during the ministry of Pitt. The rate of income tax in Great Britain varies from year to year, being 8d. in the pound for 1900. Incomes under £150 are usually exempted. In the United States an income tax was first imposed in 1861 of 3 per cent, on in- comes over $800, those derived from United States bonds being IVi per cent.; citizens of the United States residing abroad were taxed 7% per cent. In 1865 the tax was increased from 3 to 5 per cent., and the 5 per cent, tax on in- comes over $10,000 was changed to 10 per cent, upon the excess over $5,000. In 1867 (the exemption having been as low as $600) the tax was uniformly 5 per cent, on all incomes in excess of $1,000. The tax ceased June 30, 1870. The entire amount realized in 10 years was nearly $365,000,000, affecting about 250,000 persons. An income tax was again imposed in 1894, as a feature of the tariff act of that year. But this feature of the act was declared unconsti- tutional by a decision of the United States Supreme Court in 1895. The income tax law of 1913 was ap- plied to incomes exceeding $3,000 and $4,000 in the case of married persons, a tax of 1 per cent, being levied on all incomes exceeding the minimum, and an additional tax on higher incomes as in this schedule: A7id not And not Exceeding over Exceeding over 1 $20,000 $50,000 4 $100,000 $250,000 2 50,000 75,000 5 250,000 500,000 3 75,000 100.000 6 500,000 1 All payers of income shall deduct an- nual legal tax excepting: dividends on stocks and corporations, interest on trust funds, payments to a corporation. The law of 1916 was essentially the same, with important modification. The "nor- mal" rate was doubled and there were "additional" rates, especially in the case of large incomes. The Income Tax bill of 1916 doubled the above taxes, to provide for extraor- dinary expenses of the government. The act was amended in 1917 to provide additional revenue for war purposes. Additional amendments were made hy the War Revenue act of 1918. Many of the States levied an income tax, similar
