st 
FLOATING OF TIMBER. 565 
or to convenient places for collecting them into rafts. The 
lumbermen usually haul the timber to the banks of the rivers 
in the winter, and when the spring floods swell the streams and 
break up the ice, they roll the logs into the water, leaving them 
to float down to their destination. If the transporting stream 
is too small to furnish a sufficient channel for this rude naviga- 
tion, it is sometimes dammed up, and the timber collected in 
the pond thus formed above the dam. When the pond is full, a 
sluice is opened, or the dam is blown up or otherwise suddenly 
broken, and the whole mass of lumber above it is hurried down 
with the rolling flood. Both of these modes of proceeding ex- 
pose the banks of the rivers employed as channels of flotation to 
abrasion,* and in some of the American States it has been found 
necessary to protect, by special legislation, the lands through 
which they flow from the serious injury sometimes received 
through the practices I have described.t 
bear a severer climate than the oak, the oak than the beech. ‘“‘ These paral- 
lelisms,” says Vaupell, ‘‘ are very interesting, because, though they are entirely 
independent of each other,” they all prescribe the same order of succession.— 
Bigens Indvandring, p. 42. See also Bere, Das Verdringen der Laubwéiilder 
im Nordlichen Deutschland, 1844. HryrEr, Das Verhalten der Waldbiume 
gegen Licht und Schatten, 1852. Srarrine, De Bodem van Nederland, 1856, 
i., pp. 120-200. VaupPreLi, De Danske Skove, 1863. Knorr, Studien tiber 
die Buchen- Wirthschaft, 1863. A, Maury, Les Foréts dela Gaule, pp. 73, 74, 
877, 384. 
* Caimi states that ‘‘a single flotation in the Valtelline, in 1839, caused 
damages appraised at $250,000.”—Cenni sulla Importanza e Coltura det Bos- 
chi, p. 65. 
+ Many physicists who have investigated the laws of natural hydraulics main- 
tain that, in consequence of direct obstruction and frictional resistance to the 
flow of the water of rivers along their banks, there is both an increased rapid- 
ity of current and an elevation of the water in the middle of the channel, so 
that a river presents always a convex surface. Others have thought that 
the acknowledged greater swiftness of the central current must produce a 
depression in that part of the stream. The lumbermen affirm that, while 
rivers are rising, the water is highest in the middle of the channel, and 
tends to throw floating objects shorewards; while they are falling, it is lowest 
in the middle, and floating objects incline towards the centre. Logs, they say, 
rolled into the water during the rise, are very apt to lodge on the banks, while 
those set afloat during the falling of the waters keep in the current, and are 
