218 



Prof. J. W. Judd. 



[Nov. 19, 



But at Cairo, according to M. Linant de Bellefonds (Linant Bey), 

 the flow per second amounts only to 414 cubic metres at low water, 

 and 9440 cubic metres at high water. 



If these numbers can be relied upon, the Nile in this part of its 

 course loses nearly 40 per cent, of its water in a distance of 240 miles 

 when it is low, and nearly 8 per cent, when it is in flood ! 



M. Talabot has calculated tbat only 90,000 millions of cubic metres 

 of water are discharged per annum from the principal mouth of the 

 Nile, which gives an average discharge of 2680 cubic metres per 

 second ; while M. Girard estimates that only a comparatively small 

 quantity escapes by the Bosetta and Damietta mouths. 



Although we shall not be able to calculate the exact loss of the 

 Nile by evaporation in the course of 1400 miles, through one of the 

 hottest and driest regions of the globe, yet we cannot doubt that this 

 loss is enormous. Now the effect of this constant evaporation must 

 be to concentrate the saline matters held in solution, and we might 

 therefore anticipate that the waters of the Nile in Lower Egypt would 

 contain an exceptionally high percentage of saline matters in solu- 

 tion. 



But what are the actual facts of the case ? 



Dr. C. Meymott Tidy has recently made a series of analyses of the 

 Nile-water taken at Cairo during each month of the year, and 

 the results which he has obtained are of the greatest interest to 

 geologists. These analyses enable us to make the following com- 

 parisons, which we have arranged in tabular form* : — ■ 



Total solids in grs. per gallon -| 



Filtered 

 water 

 from 

 Nile. 



Filtered 

 water 

 from 



Thames. 



Filtered 

 water 

 from 

 Lea. 



Filtered 

 water 

 from 



Severn. 



Filtered 

 water 

 from 

 Shannon. 



9 53 

 to 

 14-33 



18-24 



to 

 21 -63 



17'99 



to 

 23 -34 



13 -95 



to 

 22-75 



15-30 



to 

 20-20 



Proportion of lime „ -| 



2-05 



to 

 4 35 



6-89 



to 

 8-74 



6-16 



to 

 9-28 



4- 03 

 to 



5- 43 



5-82 



to 

 7-28 



Hardness before boiling . . . . -| 



5 -0 

 to 

 8-0 



12-9 

 to 

 14 3 



13-0 

 to 

 15 9 



10 -o 

 to 

 14 3 



9-5 

 to 

 12-5 





1 2 

 to 

 2-8 



3*1 



to 

 4 2 



3- 3 

 to 



4- 4 



5 -0 

 to 

 9-5 



3 5 

 to 

 4-7 



* " Journal of the Chemical Society," yol. xxxyii, 1880, " Transactions," pp. 268 

 —327. 



