Full resolution (JPEG) - On this page / på denna sida - Second part - VII. Forestry - 2. Forest Industries. By E. Arosenius, Ph. D., Royal Central Bureau of Statistics, Stockholm - Floating, by Th. Örtenblad, Chief Master of Forest, Umeå
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654
VII. FORESTRY OF SWEDEN’.
into sections, and the time of building. After the work has been completed,
the final inspection takes place, and the floating-way is declared open;
simultaneously the Governor of the Län issues regulations for a Floating company,
which has to superintend the floating and levy costs upon the respective floaters;
these costs include amortization on the building of the floating-way.
Some of our large rivers, without any alteration, and in the very same
condition as Nature produced them, are used for timber floating, in greater or
smaller portions of their course. For the adaptation of the tributaries,
proportionally more work and expense are generally required, and consequently
they have been later adapted to floating than the main rivers. At present most
of them are probably cleared, but there are a few which are still uncleared.
Whether it pays to establish a floating-way or not, depends upon the amount of
timber which can be expected to be floated down it, and upon the costs of
adaptation. As a rule, it may be said that it pays to adapt even quite small
water-courses for this purpose.
In the main waters of a large river the work of making a floating-war
consists principally in blasting away rocks which form obstructions, building
wooden troughs to regulate streams or waterfalls, or to narrow the water-course,
building facings along such river-banks where the strand is specially liable to get
washed out, and placing booms to guide the floating timber in the desired
direction, thus protecting low strand-meadows, mills and other water-works, bridge
piers, and the like. In these large rivers, and besides in such smaller
watercourses as flow direct into the sea, sorting-booms are placed at their mouths,
where the floated timber is sorted according to the marks which it bears and
delivered to its respective owners. In the smaller rivers, besides the aforesaid
arrangements, it is frequently necessary to build dams to regulate the depth of
the water; since these water-courses are not, like the large rivers, fed by the
melting snow in the high mountains, they would otherwise contain sufficient water
for floating only during the spring floods. The dams are built either at the
outflow of these rivers from some lake or tarn, which by damming up can be
used as a water reservoir (which is the most usual manner), or at the lower
end of some swamp, which then is made to serve the same purpose, or else
in some part of the water-course that runs more slowly (dead water). The dams
consist of stone coffers, strengthened at the front side by banks of earth. In the
dam there are openings made, which by means of hatches can be entirely or
partially closed, whereby the height of water can be regulated. A special opening
(the outlet-sluicer or »shoot») is made in the dam for the escape of the logs.
Like the other openings it is provided with timbered walls and a somewhat
sloping floor of round timber.
Floating-channels (flumes) can generally not be dispensed with in our smaller
floating-ways. A precipitous stream with small water-supply, a large water
fall, irregular river-beds with large stones at the bottom, — such conditions make
floating channels indispensable. The trough or flume is made of timber and
either supported by trestles or by beds of timber or stone, the latter when the
flume lies low. In certain places the wooden channels have been superseded by
flumes of sheet iron, which have proved practical. — To ensure good floating, a
tolerably equal depth of water all through the channel should be maintained.
Consequently, the channel must be made narrower where its inclination is greater.
The width should be relatively large at the beginning of the channel and thai
decrease somewhat, because part of the water is always lost by evaporation and
leakage. The width and depth of the channel is besides adapted according to the
supply of water and the quantity of timber to be floated. In a well built
floating-channel an incredibly large quantity of timber can be conveyed, even if the
dimensions of the channel are not considerable.
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