SUN SUNDAY SCHOOLS. 



449 



ceive that the sun is inhabited, which better agrees 

 with the wise use made of space by a beneficent 

 Omnipotence. 



Parallax of the Sun. Parallax and horizontal 

 parallax have been explained in the article Parallax. 

 The horizontal parallax of the sun has been known 

 with greater accuracy since the transit of Venus 

 over the sun's disk in 1761 and 1769. As the 

 orbit of the earth includes that of Venus, the latter 

 must sometimes appear between us and the sun. 

 The duration of such a transit for the centre of the 

 earth may be calculated ; and on comparing this 

 with the duration actually observed on the surface 

 of the earth, the difference of the two results 

 enables us to deduce the horizontal parallax of the 

 sun, and hence the distance of the two luminaries 

 from each other. In this way the mean horizontal 

 parallax of the sun has been estimated by Durejour 

 at 8' 8" and by Biot at 8' 7'', which makes the 

 mean distance of the sun from the earth amount to 

 23,439 times the radius of the earth (which is about 

 4000 miles in length), or, in round numbers, 

 94,000,000 miles. If this horizontal parallax is 

 taken but one tenth of a second smaller, we must 

 add to this distance an amount equal to 215 times 

 the radius of the earth, which explains the difference 

 in the statements of the distance. This distance 

 having been ascertained with tolerable accuracy, 

 we possess the measure of our whole planetary 

 system, as, according to the second law of Kepler 

 (q. v.), the cubes of the mean distances of the 

 planets from the sun are as the squares of the 

 periods of their revolutions (which have long been 

 known). Therefore the determining of this dis- 

 tance is of the highest importance. Respecting the 

 transit of Venus, see Lalande's Astronomic, Enke's 

 Distance of the Sun from the Earth, by the Transit 

 of Venus in 1761, and the Transit of Venus in 1769 

 (in German). See Transit. 



Spots on the Sun Spots of irregular form are 



often observed in the disk of the sun, in greater or 

 less number. They appear in the centre dark, 

 and towards the margin have a whitish-gray 

 umbra, which, however, is often observed spreading 

 over large surfaces, without that black centre. 

 They originate and disappear, sometimes quickly, 

 and without apparent cause, in the middle of the 

 disk ; but more frequently are observed to rise on 

 the eastern margin, and move towards the western, 

 where, thirteen days after being first seen, they 

 disappear, and again appear on the eastern margin 

 after a little longer period. The spots appear to 

 revolve round the sun in about twenty-seven days. 

 At particular seasons, they move over the sun in 

 straight lines ; at all other times, in lines more or 

 less curved; and the paths described by different 

 spots observed at the same time are always parallel 

 to each other, and always have their curvature and 

 position determined by the season. They appear 

 broadest when near the middle point of their pas- 

 sage. All this is satisfactorily explained, if the 

 spots are considered to adhere to the sun, and the 

 latter is considered to turn according to the order 

 of the signs round its axis, which is inclined at an 

 angle of 824 to the ecliptic of the earth. The real 

 duration of this rotation, as deduced from the ap- 

 parent rotation of twenty-seven days, is equal to 

 twenty-five days. This difference is occasioned by 

 the fact that the earth, from which this rotation is 

 observed, is itself moving in the mean time. Her- 

 echell's opinion on the nature of these spots we 

 have mentioned in the previous part of this article. 



SUN-DIAL. See Dial 



SUNDA ISLANDS ; a group of islands lying to 

 the south of Farther India. The principal islands 

 of the group are Sumatra, Borneo, and Java. (See 

 the articles). The straits of Sunda lie between 

 Sumatra and Java. 



SUNDAY; the first day in the week, which has 

 its name from the sun, as this day was already 

 called dies solis with the Romans. It is celebrated 

 by Christians in commemoration of Christ's having 

 risen on the first day of the week. It was also on 

 the first day of the week that the Holy Ghost was 

 poured out upon the disciples. We have given a 

 history of the Christian Sunday under the article 

 Sabbath, and shall here only refer the reader, for 

 more information on some points, to Hallam's Con- 

 stitutional History of England (ch. vii. viii.) In 

 the church services of Europe, the Sundays are 

 named from the feasts which precede them, or 

 from the collects or passages of Scripture with 

 which the religious service was formerly com- 

 menced on the several Sundays: 1. Sunday after 

 New Year, so called when new year begins on one 

 of the four last days of the week. 2. Sunday after 

 Epiphany, which vary from one to six, according 

 to the time of Easter. 3. Septuagesima, Sexa- 

 gesima, and Esto mihi (in the English church, quin- 

 quagesima Sunday}. The third has its Latin name 

 from the beginning of the lesson of the day (Psalm 

 Ixxi, 3). 4. Sundays in Lent. Their names are 

 taken from the words with which the lessons of the 

 day begin: Invocavit (Psalm xci, 15); Reminiscere 

 (Psalm xxv, 6); Oculi (Psalm xxv, 15); Let-tare 

 (Isaiah Ixvi, 10); Judica (Psalm xliii, 1); Pal- 

 murum, Palm Sunday. 5. Sundays after Easter, 

 six in number, which almost all have names of re- 

 joicing: Quasimodogcniti (1 Peter ii, 2), or Whit- 

 sunday (see Pentecosf) ; Misericordias Domini 

 (Psalm xxiii, 6, or Psalm Ixxxix, 2) ; Jubilate 

 (Psalm Ixvi, 1); Cantate (Psalm xcvi, 1); JRogate 

 (Matt, vii, 7); Exaudi (Psalm xxvii, 7). 6. 

 Sundays after Trinity. The feast of Trinity was 

 established in 1150. The greatest number of these 

 Sundays is twenty-seven : the number depends upon 

 the time of Easter. The later Easter falls, the 

 more Epiphany Sundays and the fewer Trinity 

 Sundays are there. 7- Sundays in Advent. (See 

 Advent.) 8. Sunday after Christmas, so called 

 when this festival falls upon one of the first four 

 days of the week, reckoned from Monday. (See 

 Festivals.') In the English church, the sixth 

 Sunday after Easter is called Sunday after Ascen- 

 sion, and the seventh Whitsunday. 



SUNDAY LETTER. See Dominical Letter. 



SUNDAY SCHOOLS. The founder of the 

 modern Sunday schools was Mr Raikes, editor of 

 the Gloucester Journal. Struck with the wretched 

 appearance of a number of children whom he saw 

 playing in the street in the suburbs, he was informed 

 by an inhabitant to whom he addressed himself, 

 that on Sundays, when they were released from 

 work, and the few who enjoyed the benefit of any 

 instruction during the week, were let loose from 

 school, they presented a more afflicting sight of 

 misery and vice. This observation immediately 

 suggested to him the idea that the profanation of 

 the day might be prevented by putting them to 

 school ; and he engaged several women, who kept 

 schools in the neighbourhood, to receive such 

 children as he should send to them on Sundays, 

 and instruct them in reading and the catechism 

 paying each of them a shilling for Iheir day's worV 

 2 F 



