The dam across the Croton is 250 feet in length, and
40 feet high; 70 feet thick at the bottom, and 7 at
the top, built of stone and cement. A pond is thus
created about 5 miles long, covering 400 acres, and
estimated to contain 500,000,000 gallons of water.
Its elevation above tide water is 153 feet. Erom
the gateway in the dam the aqueduct proceeds,
sometimes crossing valleys by embankments,
sometimes beneath the surface, and through tun-
nels in solid rocks, until it reaches Haerlem
River, which it crosses on a magnificent stone
bridge, 1450 feet in length, and 124 feet high.
This bridge is supported by 14 stone piers, 8 of
the arches being of 80 feet span, and the remain-
ing 6 of 50 feet. The aqueduct throughout is
built of stone, brick, and cement, arched over
and under, 8 feet 5 inches high, 6 feet 3 inches
wide at the bottom of the side walls, and 7 feet
8 inches at the top. It has a descent of 13|
inches per mile, and will discharge 60,000,000
gallons of water in 24 hours. It delivers its
water into a receiving reservoir at Eighty-Sixth
Street, 38 miles from the dam, which covers 34
acres, and contains 150,000,000 gallons of water.
From this to the distributing reservoir on Mur-
ray's Hill, at Fortieth Street, 2j miles from the
receiving reservoir, the water is conveyed in iron
pipes. This reservoir is a massive and beautiful
piece of stone masonry, laid in cement, 43 feet
high above the street, containing 25,000,000 gal-
lons. Its surface is 115 feet above tide water.
Thence the water is distributed over the city in
iron pipes. The great mains are 36 inches in
diameter. In 1852, 215 miles of pipe had been
laid. The head is sufficient to carry the water
into the upper stories of the houses, and to sus-
tain several beautiful jets-d'eau in different parts
of the city. At the fountain in the Park, when
the water is forced into the air in a single col-
umn, it rises to the height of between 60 and 70
feet. There are a great number of free hydrants
in all parts of the city, from which the poor supply
themselves, and water is furnished for cleansing
the streets. The supply from the river is con-
sidered adequate to meet the wants of a popula-
tion three or four times greater than the city
now has. The daily consumption is now about

30,000,000 of gallons.

The following is the result of an analysis of
the Croton water by Prof. Benj. Silliman, Jr.: —

Chloride of sodium,and a trace of potassium, .167

Sulphate of soda,......153

Chloride of calcium,.....372

Chloride of aluminum,.....166

Phosphate of alumina,.....832

Carbonate of lime,.....2.131

Carbonate of magnesia,.....662

Sulphate of lime,......235

Silica, colored by manganese, .    .    .    .077

Carbonate of soda, equivalent to nitrates and
crenates of do. and loss,    .    .    .    1.865

Total solid, in one gallon, after ignition . 6.66

Carbonic acid in ditto, in cubic inches, . 17.817

Of the action of this water upon lead, after an
experiment of 5 weeks' continuance, the professor
says, “ The lead in this water looks as bright
and fresh as the day it went in, and the water
itself is not in the least turbid.''

The entire cost of the aqueduct to the city has
been about $13,000,000. The revenue now
amounts to half a million annually, and is rapidly
increasing.

New York has now an effective system of public
schools, by which all the children between the
ages of 4 and 16 are free to receive instruction as
a common right. A society, called the “ Free
School Society,'' was formed in 1804 by many
principal citizens, and afterwards incorporated,
“ to provide for the education of poor children,
not belonging to, nor provided for, by any reli-.
gious society.'' In 1826, the charter of this
society was modified, and its title changed to the
“ Public School Society of New York,'' and it was
required “ to provide, so far as its means might
extend, for the education of all children in the city
of New York, not otherwise provided for, whether
such children be or be not the proper objects of
gratuitous education.'' _# To this society, until
within a few years past, was intrusted the man-
agement of all the public schools of the city.
They had under their care 16 schools, for which
large and convenient buildings were provided;
and 48 primary schools, for which apartments
were leased in other buildings, besides several
for colored children. By a law of the state, of
comparatively recent date, public district schools
have been established, in addition to those under
the direction of the School Society, which are also
well instructed and flourishing. The number of
public schools of New York, in 1851, was 207;
the number of children taught, 107,000. The
whole expense of maintaining the schools for that
year was $274,794-59; which is an average of
$6^-86j per scholar. The funds for defraying these
expenses are derived partly from the Common
School Fund of the state, of which the city re-
ceived its due proportion; partly from an assess-
ment upon the citizens for an amount equal to
their appropriation from the fund, as a condition
of receiving the same; and partly by a special
tax of 4-80ths of 1 per cent, on the valuation
of property in the city.

In 1846 the city of New York resolved, by a
very large majority in a popular vote, to establish
a free school of a higher order, perhaps, than any
which had been hitherto projected in our country;
to be known by the name of the “ Free Academy.''
For this school a noble building has been erected on
the corner of Lexington Avenue andTwenty-Third
Street, and the institution was opened January
27, 1849. It was established by the Board of
Education, under an act empowering them to
establish a free academy, “ for the purpose of ex
tending the benefits of education gratuitously to
those who have been pupils in the common
schools of the city and county of New York.''
A thorough knowledge of the branches taught
in the common schools qualifies for admission
into the academy, where the education of the
pupils is to be continued onward, branching, as it
proceeds, towards the various divisions of the field
of knowledge, as their preferences respectively
may lead them. The plan of the institution is
designed to be intermediate between the college
system and that of the Polytechnic schools of
Europe, embracing portions of both of these
systems. It was organized with a corps of 10
instructors, embracing, besides the principal,
professors of Latin and Greek, of mathematics
and natural philosophy, of chemistry, of history
and belles-lettres, of the French, Spanish, and
German languages, and of drawing.

The building erected for the Free Academy is