SECTIONAL TRANSACTIONS.—M. 573 
operation of mole drains, their shape and the changes which take place with 
age, have been examined. Observations have been made on the permeability 
of the soil in the field and its seasonal variations. 
Dr. H. Janert.—Drainage investigations on the Continent (11.10). 
Many soils in Germany require amelioration to make farming profitable 
and to intensify cropping to the level necessary to provide home-grown 
foodstuffs for the whole population. ‘To this end the German states have 
always paid careful attention to land amelioration work, and a special 
organisation was set up to lead and to supervise amelioration generally and 
drainage in particular. 
Land amelioration boards exist in all the German states and possess a 
large staff of trained amelioration experts, called Kulturtechniker. The 
duties of these experts are very diversified and include irrigation, cultiva- 
tion of moor and marsh land, and particularly drainage. 
It is now fully recognised that efficient drainage can only be expected if 
the water and soil conditions are carefully investigated and taken into 
account. The soil conditions are of particular importance in determining 
the appropriate drain depth and separation. Before modern methods of 
soil investigation were introduced into drainage practice, the soil conditions 
were estimated simply by practical experience. This was found to be 
most unreliable, and it has been shown by field and laboratory researches 
that close relations exist between the results of certain laboratory tests and 
the response of a soil to drainage. 
These relations apply only to tile drainage, which, however, becomes 
uneconomic in the case of the extremely heavy soils. In some of these 
mole draining can be successfully employed, but in others the moles do not 
hold, and some internal support must be provided for the mole channels. 
A new method for this purpose is proposed and described. 
Mr. J. H. BiackaBy.—Drainage machinery (with a note on the 
measurement of outflow) (11.35). 
Mole draining requires considerable power, a variation from 7 to 23 
drawbar horse power being shown in the records of tractor working. The 
methods of providing this power are a team of horses, a portable winch 
operated by hand, horse or low-powered engine, steam cable engines, direct 
tractor haulage and tractor cable haulage. Each has advantages and limita- 
tions. Mole ploughs in this country are essentially of simple form ; there 
are points in construction which make for good work. Continental machines 
have been elaborated for various purposes. Mole draining can be done 
very cheaply. Mole drains have lasted fifty years, shallow tractor-drawn 
mole drains have worked well for five or six years. 
Tile drainage is comparatively expensive by reason of the hand labour 
involved. Various forms of excavator have been developed to minimise 
this and speed up the work. Ditch cleaning has also been mechanised. 
For arterial watercourses, excavators of varying size of the drag-line or grab 
type are used. 
A meter for measuring drainage outflow has been designed and tried out 
in the field by the Institute for Research in Agricultural Engineering. 
This meter is automatic and self-recording and can deal with rates of flow 
from zero up to 4 gallons per minute. 
DISCUSSION (12.0). 
