466 



NA TURE 



[March i6, 189^ 



the description of the much more modern one located at 

 Rodah. 



The nilometer, or " mikyas," on the island of Rodah 

 now visible, is stated to have replaced one which was 

 brought thither from Memphis at some unrecorded date. 

 Makreezee in 141 7, according to Ebers, saw the remains 

 of the older nilometer. 



The present mikyas is within a covered vault or 

 chamber, the roof being supported on simple wooden 

 pillars. In a quadrangular tank communicating with the 

 river by a canal is an octagon pillar on which the Arabic 

 measurements are inscribed. These consist of the pic 

 (variously called ell or cubit) = 054 metre, which is 

 divided into twenty-four kirats, in consequence of the 

 rise of the river bed in relatively recent times, the nilo- 

 meter is submerged at high Nile to a depth of two 

 cubits. 



The rise of the Nile can now be carefully studied, as 

 gauges are distributed along the river. We have the 

 Aswan gauge from 1869, the Armant gauge from 1887, 

 the Suhag gauge from 1889, and the Asyut gauge from 

 1882. The distances of these gauges from Aswan are as 

 follows : — 



Kilometres 

 Aswan ... ... ... ... o 



Armant 200 



Suhag 447 



Asyut ... ... ... ... ... 550 



Rodah 941 



The Rodah gauge is not to be depended on as the 

 movements of the Barrage regulation destroy its value 

 as a record. The heights of the zeros of these gauges 

 above mean sea level are as follows : — 



Metres. 



Aswan 84-158 



Armant 69-535 



Suhag 56*00 



Asyiic 53'io 



Rodah I3'i4 



Great vagueness arises in there being no very obvious 

 distinction between the gauge readings reached in sum- 

 mer and that from which the rise is continuous. There 

 are apparently rainfalls in the end of spring of sufficient 

 power to raise the Nile visibly in summer, just as muddy 

 rises have been seen in winter to pass down the valley, 

 leaving a muddy mark on the rocks at Aswan and 

 Manfalut. Independently of the actual gauge-read- 

 ing of the rise, there are facts about it which strike 

 every beholder. At the commencement of the rise we 

 have the green water. This occurs in June, but varies 

 in date as much as the top of the flood varies. 



From the fact that modern observations show that the 

 very beginning of the rise, and the first flush, second flush, 

 and final retirementvary, it seems evident that the ancient 

 Egyptians could not have had any fixed zero-gauge or 

 time for the real physical fact of the rise, but must have 

 either deduced from a series of observations a mean 

 period of commencement, or a mean arrival of the red 

 water, or a mean rising up to a certain gauge. 



First to deal with the green water. Generally when 

 the rise of an inch or two is reported from the nilometer 

 at Rodah, the waters lose the little of clearness and fresh- 

 ness they still possessed. The green colour is the lustre- 

 less hue of brackish water within the tropics, and only 

 the finer class of modern filter can render such water 

 clear. The colour is really due to algse. 



Happily, the continuance of this state of the water 

 seldom exceeds three or four days. The sufferings of 

 those who are compelled to drink it in this state, from 

 vesicary disease, even in this short interval, are very 

 severe. The inhabitants of the cities generally provide 

 against it by Nile-water stored in reservoirs and tanks. 



Col. Ross, R.E., noticed in 1887 and in 1890, when, 

 owing to the slow retreat of the Nile, the irrigation officers 



NO. 1220, VOL. 47] 



had to hold back many basins in the Gizah province ; 

 and also in 1888, when the water remained long stagnant ; 

 that the basin-water got green — showed the algae and 

 smelt marshy, just as the June green water does. 



Hence it has been argued that as the Nile-water in the 

 bed of the stream — even in very slow-flowing back-waters 

 — does not become green, the greenness must be pro- 

 duced by an almost absolute stagnation of the water. We 

 know of great marshes up above Gondokoro, and hence 

 it is thought that the green water of summer, which comes 

 on suddenly, is this marsh-water being pushed out by the 

 new water from behind, and that is why it heralds the 

 rise. No one has so far minutely observed the gradual 

 intrusion of the green water. 



The rise of the river proceeds rapidly, and the water 

 gradually becomes more turbid. Ten or twelve days, 

 however, elapse before the development of the last and 

 most extraordinary of all the appearances of the Nile, 

 thus described by Mr. Osborn ^ : — " It was at the end of 

 — to my own sensations — a long and very sultry night, 

 that I raised myself from the sofa upon which I had in 

 vain been endeavouring to sleep, on the deck of a Nile 

 boat that lay becalmed off Benisoueff, a town of Middle 

 Egypt. 



" The sun was just showing the upper limb of his disc 

 over the eastern mountains. I was surprised to see that 

 when his rays fell upon the water, a deep ruddy reflection 

 was given back. The depth of the tint increased con- 

 tinually as a larger portion of his light fell upon the 

 water, and before he had entirely cleared the top of the 

 hill it presented the perfect appearance or a river of 

 blood. Suspecting some delusion, I rose up hastily, and 

 looking over the side of the boat saw there the confirma- 

 tion of my first impression. The entire body of the water 

 was opaque and of a deep red colour, bearing a closer 

 resemblance to blood than to any other natural pro- 

 duction to which it could be compared. I now perceived 

 that during the night the river had visibly risen several 

 inches. While I was gazing at this great sight, the Arabs 

 came round me to explain that it was the Red Nile. The 

 redness and opacity of the water, in this extraordinary 

 condition of the river, are subject to constant variations. 

 On some days, when the rise of the river has not exceeded 

 an inch or two, its waters return to a state of semi -trans- 

 parency, though during the entire period of the high 

 Nile they never lose the deep red tinge which cannot be 

 separated from them. It is not, however, like the green 

 admixture, at all deleterious ; the Nile water is never 

 more wholesome or more deliciously refreshing than dur- 

 ing the overflow. There are other days when the rise of the 

 river is much more rapid, and then the quantity of mud 

 that is suspended in the water exceeds, in Upper Egypt, 

 that which I have seen in any other river. On more than 

 one occasion I could perceive that it visibly interfered 

 with the flow of the stream. A glassful of it in this state 

 was allowed to remain still for a short time. The upper 

 portion of it was perfectly opaque and the colour of blood. 

 A sediment of black mud occupied about one quarter of 

 the glass. A considerable portion of this is deposited 

 before the river reaches Middle and Lower Egypt. I 

 never observed the Nile water in this condition there, and 

 indeed no consecutive observations exist of the reddening 

 of the water. It is quite clear that the reddening cannot 

 come from the White Nile, but must be the first floods of 

 the Blue Nile and the Atbara coming down." 



Rate of Rise of the A^z7^.— The rate in flood is i| days 

 from Wady Haifa to Aswan and six days from Aswjln to 

 Rodah (941 kilometres). In very high Niles this is per- 

 haps accelerated to five days. In the early flood rising 

 from, say, one cubit Aswan to six cubits, where there. are 

 many dry sandbanks, and the spreading out of the river 

 is considerable, and there is an absence of overlapping 



3 " Monumental Egypt," chapter i. 



