6o 



NATURE 



[May 2 1, 1 89 1 



Thus, for instance, in Egypt the sun being used, the unit 

 of time was a year ; but in Chaldcca the unit of time was 

 a month, for the reason that the standard of time was the 

 moon. So that when people began speaking about periods 

 of time it was quite easy for one nation to conceive that 

 a period of time was a year when really it was a month, 

 and vice versd. It has been suggested that the years of 

 Methuselah and other persons who are stated to have 

 lived a considerable number of years were not solar 

 years but lunar years— that is, properly, lunar months. This 

 is reasonable, since if we divide the numbers by 12 we find 

 that they come out very much the same length as lives 

 are in the present day. 



The Egyptians, taking the sun as their measurer of 

 time, began very early with a year of 360 days. For 

 some reason or other they divided these 360 days into 

 months, probably with some lunar connection, so that 

 they had 12 months of 30 days. Now, we know that that 

 is not the true length of the year, and it is clear that any 

 nation which uses such a year as that will find its 

 festivals going through the year. Further, such a year 

 as that is absolutely useless for the agriculturist or the 

 gardener, because after a time the same month, to say 

 nothing of the same day of the month, will not mean 

 reaping-time, will not mean sowing-time, or anything 

 else. So that this 360-day year did not last very long ; 

 so long as it lasted, however, they knew that they got the 

 seasons back to months of the same name in a period 

 of 70 years. 



This method led to complications, which possibly may 

 have had something to do with the building of these 

 temples. Egypt being exclusively the gift of the Nile, 

 you can quite understand that their earliest calendar 

 would be connected with the Nile, and so one finds it. 

 We and other peoples occupying the zone in the north 

 divide the year into four seasons ; the Egyptians divided 

 it, and still divide it, into three : they have four months 

 of the flood of the Nile, then they have four months after 

 the Nile has retired, in which they do their sowing, and 

 then they have other four months which they call their 

 summer, in which they gather their harvest. 



We began, then, with a year of 360 days, and, having 

 360 days instead of 365^^, we had a cycle of 70 years, and 

 during that cycle each day of the year meant something 

 different with regard to the advance of the seasons, and 

 with regard to the work of the agriculturist and the 

 gardener to what it had meant in the preceding year. 

 But this state of things did not last long. The ist of 

 the first month fell at the summer solstice on June 20, 

 and the reason that it fell then was, that the inundation 

 of the Nile reached Memphis on that day. Whether with 

 the help of the temples or not, they soon got very much 

 nearer, and changed the year of 360 for one of 365 days, 

 which is, roughly, within a quarter of a day of the truth. 

 They had still their 12 months of 30 days, and then they 

 added an extra month of 5 days. With their perfectly 

 orientated temples they must have soon found that their 

 festival at the summer solstice — which festival is known 

 all over the world to-day — did not fall precisely on the 

 same day of the new year, because, if 365 days had ex- 

 actly measured the year, that flash of bright sunlight 

 would have fallen into the sanctuary just as it did 365 

 days before. But what they must have found was, that 

 after an interval of four years it did not fall on the first 

 day of the month, but on the day following it. They at 

 once faced this, and found out that 365 days did not 

 exactly make a year, but that they had to do with a 

 quarter day in addition. What the Chinese did was this : 

 every fourth year, instead of adding 5 days to their 360, 

 they added 6 days, and in that way they practically 

 brought the calendar right. 



Theory indicated that retaining the 365-day year, the 

 1st of the first month would come back to its exact 

 relationship to the inundation of the Nile after a period 



NO. 1 125, VOL. 44] 



of 1460 years, the 1460 years of course depending upon 

 the quarter being added (365 x 4 = 1460). 



This was known in Egypt to the priests alone. They 

 would not allow the year of 365 days, called the vague 

 year, to be altered, and so strongly did they feel on this 

 point that every king had to swear when he was crowned 

 that he would not alter the year. We can surmise why 

 this was. It gave great power to the priests ; they alone 

 could tell on what particularday of what particular month 

 the Nile would rise in each year, because they alone knew 

 in what part of the cycle of 1460 years they were, and in 

 order to get that knowledge they had simply to continue 

 going every year into their Holy of Holies one day in the 

 year as the priests did in Jerusalem, and watch the little 

 patch of bright sunlight coming into the sanctuary. That 

 would tell them exactly the relation of the true solar sol- 

 stice to their year, which was supposed to begin at the 

 solstice, and the exact date of the inundation of the Nile 

 could be found by those who could determine ob- 

 servationally the solstice, but by no others. 



In reading books on Egypt we come across another 

 cycle which is supposed to be a very mysterious one ; 

 in fact it is one which, I think, has not yet been suffi- 

 ciently investigated, and it is very well worth the trouble 

 of anybody who will give the time. They begin with a 

 year of twelve months, each of which has thirty days, 

 thus giving 360 days ; this was found not to work. They 

 then tried 365 days, but that also would not work, because 

 then the first day of Thoth (their first month) would only 

 indicate the inundation of the Nile one year out of 1460 ; 

 and then the priests interpolated the other day and got 

 the cycle right, but it was not yet quite right. In the 

 time of Hipparchus 36525 did not really represent the 

 true length of the solar year ; instead of 365*25 we must 

 write 365-242392 — that is to say, the real length of the • 

 year was a little less than 365:^^ days. 



Now the length of the year being a little less, of course 

 we should only get the absolute coincidence of the 1st 

 of Thoth with the inundation of the Nile in a longer period 

 than the 1460 years cycle ; and, as a matter of fact, the 

 1460 years had to be expanded into 1506 to fit the months 

 into the years with this slightly shortened length of the 

 year ; so we have a period which is called sothic, of 1460 

 years; and a period which is called phcenix, of 1506 

 years. 



There is a great wealth of interest connected with the 

 uses of the temples from the point of view of worship, but 

 that does not concern us here, except that it is intimately 

 connected with the next part of the subject, for I have 

 next to point out that it necessitated in Egypt, Chaldasa, 

 and elsewhere contemporaneous observations of the stars. 

 I therefore now pass from the sun to the stars. 



J. NORM.'\N LOCKYER. 



{To be continued.) 



FORESTRY IN NORTH AMERICA. 



IN continuation of the notes under the above heading 

 which appeared in Nature last January, I wish to 

 refer to a splendid paper ^ recently read by Sir Dietrich 

 Brandis, F.R.S.^ to the Natural History Society of Bonn. 

 It consists chiefly of a compilation from Dr. Mayr's 

 book, "Die Waldungen von Nord America" (Munich, 

 1890), and from works by Prof. Sargent Bernhard Fernow, 

 the present Chief of Forestry at Washington, and some 

 other authors, as well as from the Agricultural Reports 

 of the United States. 



Dr. Mayr is the son of a Bavarian State forest officer,and, 

 after studying forestry and botany at Munich, he was sent, 

 at the expense of the Bavarian Government, to observe in 

 their native forests, at diff"erent ages, certain important 



' " Der Wald in den Vereinigten Staaten von Nord America," von Dr. 

 D. Brandis in Bonn, 1891. (Sender Abdruck aus den Vcrhandlungcn des 

 Naturhistorischen Vereins, 47 Jahrg.) 



