theod 1cy

[ Gr.theos =God; dike =justice.] Philos.: A vindication of the Deity in respect of the organization of the world, and the freedom of the human will. The term is specially applied to a defense of Theism against Atheism, which Leibnitz undertook by publishing, in 1710, his E ai de Théodicée, respecting the goodne of God, the liberty of man, and the origin of the Bible. The problem theodicy proposes to solve is stated and estimated by Albert Taylor Bledsoe, LL.D., as follows: "How, under the government of an infinitely perfect Being, evil could have proceeded from a creature of his own, has ever been regarded as the great difficulty pertaining to the intellectual system of the universe." (Theodicy. Intro. II.) [OPTIMISM, 1.] "Among the infinitude of po ibilities, God, being good, must have chosen that which is best. And what is best? That which presents the most perfect order and harmony. The basis of all philosophy, therefore [according to Leibnitz), will be the conviction that whatever is is for the best; that everything is good, harmonious, and beautiful. Philosophy is a Theodicy ." -G. H. Lewes: Hist. Philos. (ed. 1880), ii. 272. the-od-o-lite, subst . [Etym. doubtful; perhaps from Gr. theōmai , for theaomai to see; hodos =a way, and litos smooth, even, plain. It occurs in Blount , ed. 1674.] A most important instrument for measuring horizontal and vertical angles, but particularly adapted for accurately measuring the former. Its principle is identical with that of the altitude and azimuth instrument; the construction and purpose of the two, however, differ, the latter being employed for astronomical purposes, while the theodolite is used for land surveying; but the better instruments of this cla may be employed for observing the altitude of celestial bodies. The vertical circle is not generally, however, of sufficient size, nor so graduated as to be available for very accurate astronomical observations. In the cut which shows the form known as a Y theodolite, from the shape of the rests in which the telescope D is free to rotate, Dis an ordinary refracting telescope, having in the principal focus of its object gla an arrangement of fibers of unspun silk, called cro wires. One of these fibers is level when the instrument is correctly set up, and two Theodolite. others like the letter X, intersect at a point in the first. When a point is to be viewed with the telescope, the telescope is moved so that the image of the point coincides with the intersection of the cro wires. The vertical limb E is divided into degrees, and is capable of being read by means of the vernier and the microscope е , to thirds of a minute. A pair of plates, A and B, constituting at their edge the horizontal limb of the instrument, are free, when unclamped, to move independently of each other. The plate A carries a magnetic compa and two spirit levels, cand c, at right angles to each other, by means of which the circle may be brought accu rately into the horizontal plane by raising or depre ing it by means of the screws, bbb . The plate A is furnished with two verniers, a , a , diametrically opposite to each other, the degrees marked on which are read off by the microscope d. cis the vertical axis, and the whole upper portion of the instrument may rotate about c, except when cis clamped by means of the screw g ; the screw h gives an azimuth motion after the screw g has been tightened. By the motion of the telescope D, on the horizontal axis of the vertical limb E, altitudes and vertical angles can be measured, while, by its motion on the vertical axis c, the angular distances between two objects can be ascertained by the readings on the horizontal circle A. Before using a theodolite, it should be properly adjusted; that is, the different parts should be brought to their proper relative positions. The theodolite is in ad just ment when the following conditions are fulfilled: 1. When the intersection of the cro -wires is in the axis of the telescope; that is, in the line which remains fast when the telescope is turned in the Y's; 2. When the axis of the attached level is parallel to the axis of the telescope; 3. When the axes of the levels on the horizontal limb are perpendicular to the axis of the horizontal limb; and 4. When the axis of the vertical limb is perpendicular to the axis of the horizontal limb. theodolite-magnetometer, s . An instrument employed as a declinometer to measure variations in declination, and as a magnetometer in determinations of force. 4058