6 BULLETIN 87, U. S. DEPARTMENT OF AGRICULTURE. 
(4) In cases where it is necessary to have an unusually abrupt 
descent in some portions of the grade, the V-shaped flume is best 
adapted to serve as a "slide" or "slip," or "chute," since it is less 
likely to become jammed, while the material being handled is held 
by its own weight in proper position in the center of the V. In a 
great many localities this particular feature of control of the log 
or stick of timber when it is "coasting" will be found very neces- 
sary in handling material from the higher mountain slopes, espe- 
cially in places where it is impossible to maintain a steady and 
equable grade from the top to the bottom of the mountain without 
too great expense, and where it may be necessary to have a form 
of construction that will carry logs or timber safely for a long dis- ! 
tance when the grade is so abrupt that it is impossible to maintain a 
sufficient volume of water in the flume to prevent the material from 
rubbing or sliding along on the sides and bottom. In such localities 
and under such conditions the V-shaped flume, when strongly con- 
structed so as to combine both the objects of flume and chute, has 
been and will be found altogether the most desirable. 
DEGREE OF ANGLE FOR "v "-SHAPED" FLUME BOXES. 
In the construction of the sections or "boxes" in V-shaped flumes 
a number of different degrees of angles have been used in the past. 
In some instances the constructors have used an angle as low as 70 
degrees, while others have constructed flumes with an angle of 110 
degrees. The results of experience and the consensus of opinion, 
however, are that the 90-degree or straight right angle is the most 
satisfactory form of V-box construction for all purposes, and this is 
the degree of angle that is referred to when speaking of V-shaped 
flumes in this bulletin unless otherwise specifically stated. 
METHODS OF CONSTRUCTING THE "v "-SHAPED FLUME. 
There are many different methods and styles of construction used 
in building V-shaped flumes, varying according to the kind of material 
to be handled. In some cases the brackets or frames that support 
the sides of the V are made from round pole wood simply flattened 
on one side so as to give an even surfaced support to the boards 
forming the u lming" or inside of the V, while the sills, stringers, 
braces, and trestling may be constructed from small round timber 
or poles, leaving only the lining or inside of the box to be constructed 
from sawed lumber. The form of construction of the different sec- 
tions of the flume, or, as they are called, " boxes," also varies in length 
from short ones of 6 feet up to those of 20 feet. In the con- 
struction of the lining or inside of the boxes, lumber of variable 
thickness and width is used. The boxes are sometimes made of only 
one thickness of boards simply joined together, but more commonly 
