640 
Mr. mann’s Treat if e 
Rates or dalles of rivers 
and flowing waters. 
Comparative degrees ot the 
mean velocities of currents 
Seconds of time wherein 
currents run 20 fathom. 
Fathom run by the current 
in 1 minute of time. 
Ratios of declivity compared 
with horizontal length. 
f athoms of length tor each 
re inch of declivity. 
Diftin&ive attributes of the various kinds 
of rivers and flowing waters. 
1 
0 
// 
0 
O 
T ^ 5oo 
f Channels wherein the reflflance from the 
] bed, and other obftacles, equal thequan- 
| tity of current acquired from the decli- 
^ vity ; fo that the waters would ftagnate 
therein, were it not for the compreflion 
and itnpulflon of the upper and back- 
waters. 
0 
2 
3 
180 
6f 
l 
TTSTTo 
8 
f Artificial canals in the Dutch and Auf- 
1 trian Netherlands. 
3 
1 
120 
10 
X 
T2T^O 
6 
r Rivers in low and flat countries, full of 
J turns and windings, and of a very flow 
] current, fubjedl to frequent and lafting 
L inundations. 
4 
if 
80 
15 
. I 
poo 
4t 
f Rivers in moll countries that are a mean 
between flat and hilly, which have a 
i good current, but are fubjed to overflow : 
Alfo, the upper parts of rivers in flat 
L countries. 
5 
ai 
55 
2I| 
t/oo 
3l 
f Rivers in hilly countries, with a ftrong 
current, and feldom fubjed to inundations : 
< Alfo, all rivers near their fources have 
this declivity and velocity, and often 
L much more. 
6 
3 
40 
3° 
2^00 
3 
f Rivers in mountainous countries, having 
< a rapid current and ftraight courfe, and 
l very rarely overflowing. 
7 
5 
24 
5° 
2.0-&0 
f Rivers in their defcent from among 
s mountains down into the plains below, 
f in which places they run torrent- wife. 
8 
8 
15 
80 
ttW 
2 
Abfolute torrents among mountains. 
I fliould 
