The Virginia Teacher VOLUME X OCTOBER, 1929 NUMBER 8 OUR CALENDAR the earth to make one complete rotation on THE measurement of time is not an its axis and "is the interval between two easy task, although it involves merely consecutive passages of a given celestial the counting of repeated motions. object across the meridian." This is a con- stant interval, but the sidereal day, measur- To aid us we have the two primary period- ed by successive passages of a given star, ic movements of the earth, namely the ro- tation of the earth on its axis, which gives differs slightly from the mean solar day, measured by successive passages of the sun. us day and night, and the revolution of the earth round the sun, which gives us the This difference arises from an apparent eas- tern motion of the sun relative to the fixed year and the seasons. Thus we might eas- ily think our problem solved for us by these stars, which motion is not constant from day physical laws. But when we consider fur- to day. This fact explains the discrepancy ther that the earth is not a perfect sphere, between the readings of an accurate watch that its axis of rotation is inclined at an and sundial. We use, therefore, the period angle to the plane of rotation, that the orbit of twenty-four hours, or civil day, corres- of revolution is not a circle but elliptic, that ponding to a mean solar day, rather than the actual time of a revolution round the either the sidereal day or real solar day, as sun varies slightly from the apparent time our unit of time. This civil day begins at of revolution because of the precession of midnight and ends at midnight at present, the equinoxes, and that the year is not an although this arrangement has not always exact multiple of the day, we can begin to been the custom. The ancient Chaldeans appreciate some of the difficulties presented and Babylonians began their day at the to a calendar maker. Then add to the above rising of the sun, the Athenians at the set- the month based upon the motion of a third ting of the sun, the Umbri in Italy at mid- body, the moon, and we have additional day, the Egyptians at midnight, and the difficulties immediately created in the mak- Romans frequently at six o'clock in the ing of a calendar. morning. This latter custom was undoubt- With this introduction it is necessary that edly the result of the account of creation we first consider the units of time now in given in Genesis, which referred to the evening and morning as forming the day. use, carefully define and understand them, determine their origin and use, in order that This custom was continued by the ancient we may be in a position to intelligently trace Gauls and Germans and can be found in our the history and development of our present expression "fortnight." calendar with its defects and apparent dis- The next division or unit of time is the crepancies. week, which has a very interesting origin As we all know, the earth rotates on its and history. A period longer than the day own axis and at the same time revolves and shorter than the month, it has at differ- round the sun. In addition, the moon re- ent times and by different people consisted volves round the earth. These physical of a varying number of days from three to phenomena are used in creating our units of eight. While the origin of the week is time, which form the basis of measurement. somewhat obscure, yet we find evidence of The day is defined as the time taken by a three day week among certain Indian 244 THE VIRGINIA TEACHER [Vol. 10, No. 8 tribes in South America, a four day week seven-day week was revived while the chil- among the natives of the Congo region of dren of Israel were journeying through the Africa, and five, six, or eight day weeks Wilderness, when the supply of manna was among the natives inhabiting other parts of omitted on the seventh day. Thus while Africa. The five day week, also, can be we find the seven-day week, we also find found in Persia, Java, New Guinea, and that the last day of the week was observed Mexico. But of more immediate interest as the Sabbath day, and not the first, as in to us we find traces of the five day week our present calendar. among the Nordic or Scandinavian people It is not surprising, therefore, to find the living in the region of the Baltic Sea in seven-day week naturally accepted by the northwestern Europe. The Northmen's Christian world. To commemorate the week of five days, with six such weeks fact that the Resurrection of Christ occur- forming a month, was divided as follows: red on the first day of the week and also T ysdag—T uesday that the foundation of the Christian Church Odinsdag—Wednesday at Pentecost occurred on the first day of the Thorsdag—Thursday week, the necessary change was made so F r j adag—F riday that the first day and not the last day of Langardag (bath-day) or Thvattdag the week might be observed as the Sabbath. (washing-day) —Saturday. For many years, however, both the first and There is no doubt concerning the deriva- last, or seventh, days of the week were ob- tion of the first four days, but it is quite served as days of rest and worship until the possible that Saturday was derived from practice was formally abolished by the some Norse divinity, rather than as ex- Council of Laodicea in 346 A. D. With the plained above. There is seemingly no reas- legal establishment of Christianity in the on to believe that the name was derived Roman Empire during the fourth century, from the classical Saturn, Saturday being various laws were enacted for the observ- used in Scandinavia long before the name ance of the Sabbath, which resulted indi- Saturn was known. The names of our rectly in establishing the seven-day week week days indicate conclusively that the as an accepted and recognized unit in the five day week was used in Britain also. calendar. The seven-day week, the other most uni- Consequently we find the seven-day week versally discovered week, is of Semitic orig- carried by the Christian missionaries into in, originating in West Asia, where it was Britain, where the five-day week was being used by the Chaldeans and Egyptians, later used. And apparently these missionaries by both the Greeks and Mohammedans. were responsible for a compromise with But it was among the Jewish people that we paganism, in which they accepted the Brit- find the full development of the seven-day ish names for five of the seven days and week. It may represent the special venera- were satisfied with giving to the two addi- tion held by these people for the number tional days of the week the names already seven, or it may have represented the num- used in other parts of the Roman Empire, ber of planets or notes in the musical scale. namely Sunday and Monday after the sun Perhaps all three circumstances exerted and moon respectively. As a result, there- their influence, although we find that ac- fore, our present week, both in number and cording to Jewish tradition this seven-day names of days, has been greatly influenced week was instituted at the creation of the by Christianity as well as by paganism. world. Allowed to lapse during the period Of the four units of time—the day, the of Egyptian captivity, the observance of this week, the month, and the year—the most in- October, 1929] THE VIRGINIA TEACHER 245 teresting of all is perhaps the month. While (moon) year and not a solar year. This the day is a unit derived from the physical explanation evidently accounts for the early action of the earth, the week the result of plan of the ancients with their limited human invention, the month owes its origin knowledge of the length of the true solar to the action of the moon as it revolves year. We know, however, that the Egyp- round the earth. The time of the moon's tians added five days to each year in an ef- revolution, reckoned from the position of fort to adjust properly this difference be- the moon among the stars to its return to tween the so-called lunar and solar years. the same position, is 27 days, 7 hours, 43 In spite of this knowledge furnished by minutes, 11.5 seconds. But again, as in the the Egyptians, the ancients especially the measurement of the day, the apparent in- Greeks and Romans, continued to make use terval between two successive full moons, of the lunar year in making their calendar called the synodical or lunar period, is 29 with months and days inserted at various days, 12 hours, 44 minutes, 2.8 seconds. times to keep the seasons in place. For in- This latter period was used as one of the stance, the Greek month contained about 28 natural units of time by the ancients, large- days and twelve such months made their ly because of ease of observation, but must year of 255 days, to which every eight years be distinguished from the calendar or civil they added ninety days divided into three month now in use consisting of from 28 to months of thirty days each.