New-York tribune., 1876-01-25
SCIENTIFIC PAVING.

MENIs-TnE TItTH-AvE. REfAVEAENT'
TO the Editor Of The TrtoU"e
SIR: Agreeably to promise made 80 long ago 'i"'
Ihold you entirely justified i'll reminding me Oh II Oh
two or three occasions, sond you the following
notes and Suggestions on tho subject Oh suee' pave
mcnts
The most essential requisites OF good street pave
ment are ~ that it shall be smooth and haId III
order to promote easy drausht; l2 that it shall give
n secure fcothold for animals. and not become poi-
ished and sppory from wear; t3 that 1t shai o. rs
nojsless and as froe from dust and mud as pos'ioo
(l tbat il shall be capable OF prompt anu 'h'rongn
cleansing (J) that it be Of durable material ana ol
aneh construction that it bo taken up IN PAGES
and quickly reaid, in order to give access 10 gas anu
water pipes and co. that it shall be Susceptibie oi
repars at all seasons of tao year, and at moderate
cost.
Roads of broken stono or gravel ike thoso III
Central Park. produce less noise, and ave moro
soour, footh,ld for animals than blocks of wood or
stone OF "a continuous surface Ike asphalI out Vey
rcouire such constant care TO prevent the formation
of rts and arc so infested with scr dust or mud
as 10 render them greatly inferior to moderately
GOOD payement of stone blocks or asphalt for city
streets subjected to heavy traffic. hey ar" eXcei-
lent for mark and suburban roads, largely devoted
10 pleasure driving; but 30 far "a Know theIe %
no trustworthy record OF any urban street oi 'Ii'
kind that has ever been maintained III sueh hl" he'
thai tho Inconvenience and annoyance from HuSt oI
mud did not in reality amount 10 POSITIVE anu
sarious nuisance TO the residents or the people Gong
business 'on either side. l must therefore, H'Ae
direct issuc with those who recommend macadamiz-
ing tho iil;h-ave The layer of cobbie-otones wm'h
covers many of ou1 streets is scarcely deserving Tho
name of plyement 1t stands thoroughly con
demncd by mere statement of the fact that horse
oaD draw upon a good stone block, or far asphalt
pavement n load three times as great as he can
move with tho sime speed upon cobble-stOhes'
pavement of good stone blocks-good. That lN'Wlth
respect to both material and forn-wili, II aid upon
an unsuitable foundation, soou form into ruts and
deprossons, and be ttle superior to cObble-stones
With the exception of tho streets around the new
Post-Oice, and Broadway below Uuio1-sqnafe'
where the blocks rest ON foundation OF concrete
oil the 81 lne plyeneRtS of thus city arc iaid directly
ON sand This in itself, quito sufficient to account
for their generally bad condition. although money
is, believe literally spent in their maintenance
and repair 1t is practically impossible to compact
the sand to uniform density before setting the
stones; and were it otherwise the blocks, being OF
varying sizes in bed area. will settle unoqUaly un-
der the repeated I;lpac;s of passing loads. A good
foundation is as necessary fOr the stability of apaye-
ment as for that of any othor structure, and bad
foundations invariably produce bad paycments.
From careful examination which have had oc-
casion TO make during the past year, have no hrsl-
tation IN expressing the opinion that if the money
expended in the construction and maintenance OF
the pavefnents in this city, during The last hiiecn
years. had been applied undcr competent pGcf'S-
sOna supervision. tho streat traffic OF the present
day could easily be carried on with lass than two
thirds the animal power now found 10 be necessary
and the percentage of reduction in the cost of wear
Il u. 4 Ia. Vpt ~
larger. | do NOS claim tlat the saving would have
shown itscf by d ponsiag with fully ouo-thirl the
number OF animals now employed. Although II
would naturally and largely take the form OF lever
and larger loads for both single and double teams,
provision would still have 10 be made. ~ now, for
that portion of the traffic represented by an aegre-
cation If fractions Of loads. 10 each Of which one
eninal and one man must be assigned.
SUITABLE FOUNDATIONS.
Among the suitable foundations for pavement,
provided lhe thickness be adapted 10 the character
of the subSoi and the nature of tn trdIc. are hs
following: Ql Hydraulic concretc, six to eight
inches in thickness; 2 ruhbIo stones set on edge,
but not in contact with tue nterstiCos hod IN with
concrete; 90 rub6le stones sct IN contact on edge,
ike the snb-pavement of elforI road; CD cohble
stoucs frully set IN form Of sand or gravel; lJi
small rubJe stones OF random sizes, ~ wc.i-col-
pacted ay.r; OF (G i layer of broken stone lad in
the manner of "a mIcadl lnizcd road OF the G. the
Grst second and third by far the best, and tuey
are named in tho order Ol their merit. Tine three
pavements winch have boon most actively con-
petpg for public favor within the lat ten wears
those OF Stone blocks. woolon block. and asp. ALI
Perhap, the best way cf discussing tlom is 10 CON-
pare the respective merits of the best Of each Kind.
Tie best sons pgresenf is one composed of r'ctan-
gular blocks set on thcir longest edge across the
street upon % concrete foundation, like that III
Broadway, below Founeenth-st
The best UOoden pareneqi is also of rectangular
blocks set o their edges the street. suit
able foundation. which should not bo any Of those
above named. Wood BLOCKS would soon DE cdeetroyci
by crushing If set upon rigid, iuoastic foundation.
4 cool asphalt pqceg,esf requires n good foundation,
preferahly either the first or second Of those men,
toned above The asphalt covering may be the
natural asphalt rock derived from the JurlSs!c
region, on the cOHfncs Of Switzerland. or il may bc
composed Of aspAaltic cement suitably prepared by
refining thc natural bumen, to which Ia added cal
careons powder 10 take the place Of the amorphous
carbonate OF lime contained in the natural asphalt
rock a description OF either method OF construct
ing this KIND of pavement wonld he too long for in
sertiOn here. IL may be mentioned, however, that
O capital distinction must be made between pave
meuts of genuine asphalt properly prepared, aud
all those patented limitations of substitutes for H.
composed of wood-tar tar pitch resin, &c.
mixed with either sand, gravel ashes, scori9. sui
phur, lime. &c, or with two more or all of them
Some of these mixtures will make a tolerably fair
sidewalk OF footDath but they are, each and all Of
thein totally unfit for carIiage-ways. Under proper
precautions the best Of them viii answer fox car
rage-way foundations. The advantages Of good
asphalt pavement are tl) That il produces dust
and thercford no mud; C2 it is comparatively noise