Green-Mountain freeman. [volume] (Montpelier, Vt.) 1844-1884, 1878-06-19

to all. Its popularity is waxing daily. 1
IS acknowledged by the most competen
Judges TO be superior to all other system,
known for ventilating. purifying and TEN.
perlng an apartment or Il building.
The best talent in the country has been
applied to S. +. V. for the past ten years
with view to reduce the cost of the detail
of its application to the minimum and il
has been reduced fully so per cent in the
past eighteen months; and an improve
ment in the results attained have been
about commensurate with the reduction OF
cost of applying.
Atmospheric air transmitted by prop
erly arranged sub-earth air duct is purer
by far than it is generally found in nature.
The duets all have an earth bottom and if
the soil is not clay, dressing of clay Is
supplied 10 the surface of the bottom, by
which mal-air is purified rs well as tenn
pered and anhydrated or dried. The most
remarkable characteristic of the sub earth
lir duct is, however. that of removing from
the air the ozone formed at times of excess
sive and near electrical discharges, which
all duirymen know to their sorrow has the
effect TO sour milk set for creaming, so
precipitatey that the milk acquires Il
mechanical condition, Il density produced
by coagulation that prevents the cream
from rising, hence it is lost. The efficiency
of this influence of the sub earth duct on
air thus changed is found to be so great
that when this condition of the air exists
TO that degree that milk coagulates in
twelve to twenty hours in ordinary milk
houses it stands its wonted time. forty
eight hours, in those in the same neigh
borhood, in which sub-earlh ventilation is
used Instances are now so numerous
where this result has been obtained that
this characteristic of S. f. V. is rs well
established as any other. All dust and
odors that air transmitted by the duet may
contain are removed in transit. The for
mer, by contact with the moisturcd surface
of the duct, SO rendered by the vapor con-
densed on it; the latter, by the antiscptic
property of the clay bottom.
The combined properties of sub-earlh
air duct are these tempering. air, admit
ted at any normal temperature where it
falls to 40' below, and rises to 1909 above
zero, in shade. and delivering it into
building at about 500 F above at all times
of anhydratng it SO that no vapor is per-
ceptible in it, with ordinary tests, where
it is discharged-of Kidding it of all dust
and all excess of ozone of supplying any
repaired volume of such purified and
tempered air and of changing it al lJitunl.
HOW ARRANGED.
An air duct is constructed in the earth
of the required length, depth and cross
section, according to the degree of temper
ing and the volume of air required to
secure the result desired. As already
stated, the bottom of all the ducts is Of
.drth, /. c., clay. The material used is any
one most economical in each
locality. Small rough, rubble stones are
generally used when attainable, though
brick side walls and arch are very COM
monty used. A good mortar of common
lime and sand, with one part OF
pure hydraulic cement to four of the NOR
lar is used in the masonry. The walls are
made as rough and uneven in the interior
face rs is convenient and neither the upper
nor the lower surface or the sollit at the
arch are plastered us filtraling water ,
through the arch has a perpetual purifying
influence.
The best result yet attained is in the
use of duct 200 feet in length and II in
depth The area of the cross section re
qulred is of course in proportion to the
of air and tempering required,
which, If very great, may require II still
greater length than 200 feet, us it IS found
preferable to augment length rather than
the cross section, the degree of tcmpering
being proportionate to the area of the
interior surface of the duct with which the
current air makes contact, hence duct
of medium cross section and great length
is more potent than short one that is |
larger in cross section.