Sept. 23. 1880] 



NATURE 



487 



plies the same relative amount of sediment as the 

 remainder of the catchment basin, I estimate the total 

 ainoHiit carried down to tlie sea annually at 6,428,8^8,2^^ 

 cubic feet. 



The removal of this amount of sediment from an area 

 of drainage of 650,000 square miles represents a lowering 

 of the surface at the rate of one foot (of rock) in 3,7oy 

 years. This is therefore the rate of " subaerial denuda- 

 tion " of the valley of the Yang-tse as far as concerns the 

 quantity of sediment removed. Of the proportion of 

 solids in solution, I have had no opportunity of judging, 

 but that the soluble matter is in considerable quantity is 

 rendered probable from the extensive limestone districts 

 traversed by this river. 



2. Tlie Yellow River or the Hoang-ho has derived the 

 appellation of "China's Sorrow" from its frequent de- 

 structive inundations. It runs a course of about 2,500 

 miles ; but, unlike the Yang-tse, its lower course has 

 frequently shifted in the course of ages, and although it 

 opens at the present day into the Gulf of Pe-chili, only a 

 quarter of a century has p issed since it emptied its waters 

 into the Yellow Sea.' The mountainous district of the 

 province of Shantung has in truth been the chief means 

 in deflecting the waters of this great river on more than 

 one occasion during the historical era from the Gulf of 

 Pe-chili to the Yellow Sea, and vice versa. 



With reference to the qicantity of water discharged by 

 the Hoang-ho I have had no opportunity of personal 

 observation. We have, however, an estimate not only of 

 the water- discharge, but also of the sediment, which Sir 

 George Staunton supplies us in his account of Lord 

 Macartney's embassy to China in 1792. It was calculated 

 that at the place where the British embassy crossed the 

 Yellow River — its junction with the Grand Canal — the 

 water was carried past at the rate of 418,176,000 cubic 

 feet per hour, or 116,000 cubic feet per second. The 

 method employed in ascertaining the quantity of sediment 

 was the measurement of the amount of mud deposited 

 from a gallon and three-quarters of water when allowed 

 to stand. From this experiment it was concluded that 

 the sediment was in the proportion of g Jg of the original 

 bulk of the water, and the annual discharge of sediment 

 was assessed at iy,j20,ooo,ooo cttbicfeet. 



However carefully these observations may have been 

 made, and however near they may approach the actual 

 discharge of water and of sediment at the time in question, 

 it seems to me that one is hardly justified in accepting the 

 result of a single observation as typical of the average 

 state of things throughout the year ; and yet Sir George 

 Staunton's estimate has never, as far as I am awai'e of, 

 been questioned. A single glance at the foregoing table 

 will convince one of the little dependence that can be 

 placed on a solitary estimation ; it will be there seen that 

 the Yang-tse discharged nine times as much water when 

 at its highest level in August as it did during the month 

 of January, when its waters occupied their lowest level.'-^ 

 Or if the question of sediment is considered, to which the 

 same objection would apply, I have the greatest diffidence 

 in accepting Sir George Staunton's estimate as being of 

 any value except as a trustworthy result of a single expe- 

 riment ; and yet, even considered as the maximum of the 

 whole year, the result is a rather startling one. While 

 the greatest amount of sediment I found in the water of 

 the Yang-tse was seven grains in the pint, and in the case 

 of the Pei-ho — as will subsequently be noticed — fifteen 

 grains in the pint, Sir George Staunton estimates the 

 sediment of the Yellow River at over eighty grains in the 

 same measure of water. Even the muddy waters of the 

 Ganges do not contain more than twenty grains of sedi- 

 ment in the pint of water. 



It is therefore not with any surprise that I find the 

 "subaerial denudation" of the Hoang-ho is estimated' at 



^ Vide Mr. Mobsman's paper, already referred to. 



^ In the case of the Ganges at Gh.a2epoor the proportion is as 1 to 14. 



3 Vide Natlre, vol. xviii. p. 16S. 



less than half that of the Yang-tse, namely, one foot in 

 i.jd^years. This estimate only refers to the amount of 

 sediment removed, and yet I cannot but consider it as 

 very liable to correction by some future observer. As 

 this is the only calculation that has ever been made, a? 

 far as I am aware, with reference to the quantities of 

 sediment and of water discharged by the Yellow River, I 

 am perforce obliged to accept it pro tanto. 



3. The Pei-ho drains the great plain which constitutes 

 the province of Pe-chili. Its length is said to be about 

 300 miles, but the lower part of its course below the city 

 of Tientsin is so tortuous that a distance of thirty miles 

 overland is converted into fifty by the river. It is at 

 Tientsin that the Pei-ho proper and the Yu-ho unite 

 together to form the main stream : the latter is generally 

 known by Europeans as the Grand Canal, but as a matter 

 of fact the canal joins the Yu-ho about 150 miles to the 

 southward. During the three winter months — December, 

 January, and Februaiy — the Pei-ho is usually frozen over, 

 the ice having a thickness of about eighteen inches ; in the 

 same season there is generally a large quantity of ice in 

 the Gulf of Pe-chili, which may[completely fill up the head 

 of the gulf. 



With reference to the water-discharge of this river, I 

 was enabled while wintering at Tientsin during the season 

 1878-79, to collect some "data" for its estimation during 

 the four months from December to March. Although 

 my estimate strictly applies to but a third of the year, 

 still from the limited rise and fall of the water during the 

 different seasons (it never exceeds six feet) I feel pretty 

 confident that it fairly represents the average rate of dis- 

 charge during the whole year. The breadth of the river 

 at the place of observation below the city of Tientsin was 

 280 feet. The following table contains the results of my 

 calculations : — 



December 



1S79. 

 January 

 February 

 March 



Surface 

 Knots per hour. 



Average 



depth. 



Feet. 



.. 14 . 



,. I4i . 



Water-discharg 

 Cubic feet 

 per second. 



■■■ 6,355 



••■ 4.389 

 ... 9,684 

 ... 10,592 



4)31,020 



7,755 



We may thus place the average discharge of water for the 

 whole year at about 7,700 cubic feet per second. 



Now with regard to the amount of sediment carried 

 past the city of Tientsin : I found the average quantity 

 during the four months in question to be nhout five grains 

 per pint. (It varied much at different times, for I found 

 as much as fifteen grains in the middle of March, while 

 in the months of January and February it did not equal 

 a grain in the pint.) This represents a proportion of 

 tV^.o by "weight," or jj^Vif ^Y "bulk'' of the average 

 discharge of water : and following the same method of 

 calculation as was employed in the case of the Yang-tse, 

 I estimate the annual discharge of sediment for this river 

 at 80,000,000 cubic feet. 



N ow the removal of this bulk of material from an area 

 of drainage, which I estimate at 55,000 square miles, 

 represents a lowering of the surface of one foot in 2j,2/S 

 years. This is the rate of " subaerial denudation " of the 

 Pei-ho basin, omitting of course the question of the solids 

 in solution. 



To show the rank that these three rivers hold in the 

 fluvial system of the globe, I have subjoined a fist of 

 fourteen other rivers, which gives'.the quantities of water 

 and sediment discharged by each, as well as the rate of 

 subaerial denudation, as far as I have been able to 

 ascertain. 



