til 



SUXDIAL. 



SUPRALAPSARIANS. 



;iie time as the clock. It does not do so in reality, but 

 the consideration of this point belongs to the article TIME. A large 

 sundial is frequently furnished with a table of the correction of sun- 

 time, to turn it into clock-time, engraved on its face ; but this is 

 generally soon corroded. Nor is knowledge of the simplest elements 

 of astronomy so widely diffused as to make such a table of any great 

 use. A person who stations himself in any place of resort which has a 

 sundial, will soon find a lounger who looks in amazement at the 



difference, perhapa a quarter of an hour, between his watch, which ho 

 knows to be right, and the shadow. The church-clock and the sun, in 

 both of which he implicitly believes, are at variance, and he is hardly 

 able to resist the melancholy conclusion that his watch has gained or 

 loci a quarter of an hour in a ten minutes' walk. Neglecting the cause 

 of thin, which w an irregularity of solar time, and has nothing to do 

 with any particular mode of reading the results, let us suppose that it 

 U nine o'clock in the morning, solar time. This means that the sun is 

 in that hour-circle which belongs to three hours before noon,oris3x 15 

 or 45 degrees from the meridian hour-circle towards the east. The 

 meridian hour circle is that which cuts the plate of the dial in the 

 line XII XII ; and the hour-circle in question (the right-hand one of the 

 two which are not shaded) cuts the dial-plate in IX IX. Now when the 

 nun is in the continuation of any plane, the shadow of that plaue is 

 '.nly that of the edge presented to the sun. The upper edge of the 

 style is common to all the hour-circles ; and its shadow is, therefore, 

 for tint time, part of that of the hour-circle in which the sun is. Hence 

 at nine o'clock before noon the line oix will be the shadow of the 

 style, o being at the intersection of the edge of the style and the dial- 

 plate (marked by a large dot in the figure). In the diagram, the day 

 has moved on about a quarter of an hour after the time just described, 

 and the shadow has advanced accordingly. There is in it a trilling 

 error of shading (it was taken from De 1'arcieux's ' Trigonometry,' a 

 work which ia very rich in well-drawn solid figures), which will serve 

 I" illustrate the subject. The time being between nine and ten 

 o'clock, the sun ought to be looking directly into the crevice between 

 the hour-circles IX and x, in which crevice there ought therefore to be 

 no shadow ; but the crevice which is entirely devoid of shadow is that 

 between the hour-circles Yin and IX, so that the sun is made to tell 

 one story on the north side, and another on the south, of the figure. 

 The reader will easily set this right, and will see that as far as the 

 whole hours are concerned, the crevices themselves might be made to 

 answer the purpose of a sundial. 



Though the preceding figure was drawn for a horizontal dial, yet 

 any other plane might be substituted. The objections to a dial are, 

 that the shadow of the style is not sufficiently well defined to give very 

 accurate results, even for ordinary purposes : that refraction, which 

 always makes the sun appear a little too high, throws the shadow a 

 trifle towards noon at all times, that is, makes the time too fast in the 

 morning, and too slow in the evening ; and that a correction is always 

 necessary in order to find mean or civil time. Even if the first objec- 

 iiild be got over, the corrections requisite for the two latter 

 would prevent persons in general from making use of the instrument. 

 If the edge of the style be not very narrow, it is necessary to have the 

 morning and evening halves of the dial separated by the breadth of 

 that edge. 



Those who understand spherical trigonometry will easily see that 

 the general problem of a sundial consists in that of finding out where 

 the hour-lines cut a given circle, as follows. Let B Q c be the circle 

 in which the plane of the dial produced cuts the heavens, and let the 

 angle CAS, which it makes with the horizon (h), and c i) N, which it 



makes with the meridian (m), be given. From p, the pole, draw Q p 

 perpendicular to the plane of the dial ; and the line joining r with the 

 centre being the continuation of the style, that joining the centre with 



Q is the continuation of what is called the sulislylc. Now in the right- 

 angled triangle ANB, we have 



cos h 

 cos N B = : , 



smm' 



whence N B is found ; to which add the latitude of the place, P N, and 

 p B is found. The equations 



tan P B . cos m = tan Q B, sin P B . sin m = sin P Q 



show how to place the substyle with respect to B, the point answering 

 to noon ; and also how to place the style with respect to the substyle. 

 To find the point v at which any given hour-line, P v, cuts the circle 

 c B, first find the angle Q p B from 



cot Q p B = tan m . cos p B ; 



and v P B, the hour-angle from noon of the sun (v being a point in the 

 shadow). The difference of these angles, Q p v, or their sum, is then 

 known ; and Q v is found from 



tan Q v = tan Q p v . sin p Q 



It will be better for the beginner to verify these steps on a correctly" 

 drawn figure, or to modify them, than to make purely algebraical 

 alterations. Also it is to be remembered that the position of the dial 

 may require both sides of it to be graduated, and the style to extend 

 in both directions, to suit all times of the year and all hours of the 

 day. 



SUNNAH. This is the name given by the Mohammedans to the 

 traditionary portion of their law ; which was not, like the Koretn, com- 

 mitted to writing by Mohammed, but preserved from his lips by his 

 immediate disciples, or founded on the authority of his actions. It 

 holds in Mohammedan theology the same place as the Mishna in the 

 Jewish doctrine, and the names agree in their derivation. The 

 orthodox Mahornmedans called themselves Sunnites, in distinction to 

 the various sects which are comprehended under the term Shiites, 

 whose distinguishing characteristic is that they recognise as lawful 

 kalifs Ali and his descendants. The Turks as a nation are Suunites, 

 and the Persians Shiites. Shiah, from which this latter name is 

 derived, signifies a party or troop. 



SUPERCARGO. [SHIPPING, SHIPS.] 



SUPERFICIES, the Latin form of the word surface, used in the 

 sense of surface, and sometimes of area. The quantity of an area is 

 called its superficial content, as distinguished from linear content or 

 length, and solid content or bulk. 



SUPERPHOSPHATE OF LIME. [CALCIUM, Superphosphate of 

 Lime.] 



SUPERSEDEAS, in law, the name of a writ used for the purpose 

 of superseding proceedings in an action. In its more general sense it 

 is used to express that which supersedes legal proceedings, although 

 no writ of supersedeas may have been used for that purpose. Thus if 

 a writ of certiorari be delivered to an inferior court for the purpose of 

 removing a record to a superior court, the writ of certiorari is said to 

 be a supersedeas of the proceedings before the inferior court. 



SUPPLEMENT (Trigonometry). The defect of an angle from two 

 right angles. Also chords or arcs of a circle or other curve which have 

 a common extremity, and together subtend an angle of two right angles 

 at the centre, are sometimes called supplemental chords or arcs. 



SUPPLY. [PARLIAMENT.] 



SUPPURATION. [ABSCESS; INFLAMMATION.] 



SUPRALAPSARIANS. In the discussions of the doctrines of 

 predestination and election, which arose out of the teaching of the 

 school of theologians at Geneva, two different views came to be taken 

 by the Calvinistic party. Some held that all the occurrences which 

 take place on the earth have been from eternity the subject of a special 

 decree of God : that God decreed to create man solely for his own 

 jlory, and to display his glory in the eternal happiness of some and the 

 damnation of others : that this decree respected not merely the end, 

 but all the means, direct or indirect, by which that end was to be 

 wrought out ; and that sin, the fall of man, and the introduction of 

 evil into the world, were decreed by God to happen as necessary means 

 to the end proposed, and God therefore so constituted man, and 

 placed him in such circumstances, that he could not but fall. The 

 persons who held these views were called Supralapaarians (supra, 

 'apsum), because, according to their system, the decrees of God 

 -espectiug the salvation of some men and the rejection of others were 



