The locks are 200 ft. long in the clear between the gates, and 45 ft
wide in the chamber at the bottom. The walls of the lower one are 29 ft.
high, and of the upper one 31 ft They are from 10 to 12 ft thick at the
bottom,

The locks are built similar to those on the new Lachine and Welland
canals, of the very best cut stone masonry, laid in hydraulic cement.
The gates are 24 in. thick, made of solid timber, somewhat similar to
those in use on the St. Lawrence canals. They are suspended from anchors
at the hollow quoins, and work very easily. The miter sills are made of
26 in. square oak. The bottom of the lower lock iis timbered throughout,
but the upper one only at the recesses, the rock there being good.

[Illustration: MAP OF THE OTTAWA RIVER AT CARILLON RAPIDS.

SECTION OF RIVER AT DAM. NOTE.--THE LOWEST DOTTED LINE IS LOW WATER
BEFORETHE DAM WAS BUILT. THEN THE LINE OF HIGH WATER WAS ABOUT A FOOT
ABOVE WHAT IS CREST OF DAM NOW.]

The rise to be overcome by the two locks is 16 ft., but except in medium
water, is not equally distributed. In high water nearly the whole lift
is on the upper lock, and in low water the lower one. In the very lowest
known stage of the river there will never be less than 9 ft. on the
miter sills.

As mentioned at the beginning of this article, four locks were required
on the old military canal to accomplish what is now done by two.

The canal was opened in May, 1882, and has been a great success, the
only drawback--although slight--being that in high water the current for