312 M. P.S. Girard on Navigable Canais. 
weight in the descending boats over those which ascend, 
a part of the volume of water necessary for the navigation 
may be raised from each of the two rivers where the canal 
terminates, to the reservoir on the summit level. This re- 
servoir would thus be supplied so much the more abundant- 
as the navigation became more active ; this is the most 
useful result that we can hope to obtain. 
Among all the points of the kingdom where so advanta- 
ous communications might be opened, | will point out, 
e example, the plateau of St. Etienne in the department 
of the Loire. An interesting memoir of M. Beaunier, En- 
gineer in Chief of Mines, shews that this plateau furr ishes 
annually 300,000 tons of pit-coals, which descend to the basin 
of the Loire on the one side, and to the basin of the Rhone on 
the other. Now which ever way these coals descend, it is 
certain that their transportations on a navigable canal, es- 
tablished according to our principles, might not only render 
null the expense of water from its sammit level, but might 
even raise a certain portion of water to the reservoir on 
that level from the lower levels. 
The memoir of M. Beaunier furnishes the fnndamental 
data of the project of communication between the Rhone 
and the Loire. ese two rivers are but 54 Kilometres, 
er 10 leagues distant from each other in this place, 15 ki- 
lometres of which are already navigable on the Canal de 
Givors, which extends from Givors to Rive de Gier- 
idea of uniting the ocean to the Mediterranean by this route 
is already very old. But what would especially character 
ize this communication over the plateau of St. Etienne, * 
that we there should find in the mass itself of heavy arti- 
eles in which that section of country abounds, a part of the 
force necessary for their transportation, since in descending 
along the canal which served for their exportation they 
might raise from the lower to the higher levels, a portion 
of the water necessary for the supply of the canal. ‘This 1s 
one of the cases where it becomes as it were indifferent 
whether we have a determined body of water in reserve: 
on the summit level of a canal, or are able to ship on this 
level an equal quantity of solid matter; this is an imme- 
diate c¢ uence of our new theory, and one of the 
a —; ones which it furnishes. 
fer having thus pointed out the advantages of this ne¥ 
theory, let us give a moment’s attention A ecaiieade the 
