MISCELLANEA. 
195 
her own — artificial means must therefore follow upon the 
principles of the laws of nature. 
The origin of all moisture^ whether atmospheric or sub- 
terranean^ is more particularly plentiful in the higher levels^ 
and hence the principle of drainage commences from the 
higher parts of a country. The engineer then has simply to 
carry the water collected in these parts along such strata as 
are impervious to moisture, and which additional moisture is 
not required until it reaches the porous soils, which, inde- 
pendent of requiring more co:iiplete saturation, are likewise 
liable to greater exhalation ; and on these he would distribute, 
by proper water-channels, such a quantity as he would con- 
sider sufficient for the purpose of promoting agricultural 
produce, at the same time providing for the due conveyance 
of a proportionate quantity to the absorbent levels situated 
lower in the descending scale. The advantages of this system 
are evident in this country, and their application very simple, 
inasmuch as the strata run, with but few exceptions, in direc- 
tions nearly parallel to each other, and hence admit of very 
simple principles for distribution of the surplus waters. This 
will give a distinct idea of the plan upon which the engineer 
may forward many of his plans for the important object of 
drainage and irrigation. 
We shall probably revert to the subject in a future number. 
On the Mineral called " OttreliteJ" by M. M. Descloizeaux 
and Damour. — Translated from the French, 
The Ottrelite has been known for some years in many 
mineralogical collections, but as there is yet no published 
description, it is classed amongst the list of Minerals of 
which the nature and properties are unknown.^^ By some it 
has been ranked with Diallage. It is named from the small 
village of Ottrez (near Stavelot), on the confines of Luxem- 
bourg and Liege, where it was first found. The great 
abundance of this mineral in all the slaty rocks near Ottrez 
