630 KANSAS CITY REVIEW OF SCIENCE. 
ENGINEERING AND MINING. 
STREET PAVEMENTS. 
WM. B. KNIGHT, CITY ENGINEER. 
In the interesting article on the subject of "street pavements," which ap- 
peared in the January number of the Review, I notice some criticisms on the 
method of putting down wooden pavements in this city which, I think convey, 
despite of a limitation noted, the impression that a very important detail of the 
construction is not sufficiently provided for, or carried out — namely, the com- 
plete filling of the interstices between the blocks so as to prevent the surface 
water from reaching the bottom of the blocks. I wish, therefore, to state that I 
always fully appreciated the importance of keeping the surface water on the sur- 
face, as a matter which adds largely to the life of the wood. 
The specifications for all this work, which I drew nearly two years ago, pro- 
vide in explicit terms for all the interstices between the blocks to be first filled 
with gravel of approved quality, to be screened and entirely free from sand, and 
of such size as to fall freely into the holes, being not less than one-quarter nor 
more than three-quarters of an inch in diameter. The gravel to be well rammed 
in with proper tools until the spaces are compactly filled to the surface. 
This, in practice, requires twice sweeping the gravel over the blocks, and 
is followed by a ramming after each loose filling. 
Asphalt paving cement is then poured (hoi) into the spaces and joints until 
they are full, and the asphalt flushes to and runs over the surface. In practice 
the average quantity of asphalt used is about one and one-half gallons to the 
square yard of pavement, sometimes requiring much more, depending mainly 
upon the closeness with which the blocks are laid; on the average size of gravel 
used, and on the degree of compactness attained in ramming it. 
As to the execution of these provisions of the specifications, the system of 
inspection, and the quantity of asphalt actually used per square yard (only a very 
small proportion of which remains on the surface) indicate a substantial compli- 
ance. 
From practical tests, afforded when street pavement has been taken up for 
various purposes, I have, as a rule, found that the asphalt had penetrated to the 
bottom of the blocks, and completely filled all the voids between them— forming 
in fact, as intended, a bituminous concrete in the interstices, and binding the 
blocks together. 
The surface of the blocks as laid, slope each way from the center of the road- 
way to the gutters on each side, and are maintained smoothly and uniformly in 
this position by the concrete foundation on which they rest, so that the water 
