Daily Kennebec journal. [microfilm reel] (Augusta, Me.) 1870-1975, 1886-01-19
I Manchester Union.
Anchor Ice.
ONE OF THE 1ScosvESIEScEs IN THE Use OF
WArER-PowER DESCRIBED.

Every winter the mills of Manchester suffer
more or less annoyance from anchor ice this
winter the trouble has been the worst ever
known from the same cause and has led many
people to make inquiries concerning the ma
ture of this kind of ice. The question What
is anchor icef" has been several times asked
Representatives of this paper, and desiring to
furnish the best information upon the sub
ject, James B. Francis of Lowell, a we'll
known and able civil engineer, who has given
the subject much thought and attention, aud
whose ideas upon it are highly regarded, was
asked to give his views. The request was
promptly complied with and the following is
the interesting result:
"A frequent Inconvenience in the use OF
water power in cold climates is that peculiar
form Of ice called anchor or ground ice. Ii
adheres to stoDes, gravel, wood and other
substances forming the beds of streams, the
channels Of conduits. ADD oriices through
which water is drawn; sometimes raising the
level Of water courses many feet by its ac-
cumulaton on the bed and entirely closing
small orltces through which water is drawn
for industrial purposes. | have been for
many years in a position t. obsarve its eff
feet. and the conditions under which it is
formed. The essential conditions are that
the temperature of the water be at its treez-
ing point, and that of the air below that
point; the surface of the water must be ex
posed to the air and there must be a current
IN the water. The ice is formed in small
needles on the surface. which would remain
IN r. and form sheet If the surface was not
too much sgitated except for u current or
movement in the body OF water sufficient TO
maintain it in a constant state of intermix-
N a lar
mel there is continual interchange of posi-
ZION of the different parts of stream; the re-
tardation Of the bed causes variation, 10 the
velocity which produc- whirls aud eddies and
a general instability in the movement OF the
water in different parts Of the section, the
result being that the water at the botto N soon
hnds its wav to the surface, and the reverse.
| found by experiment on straight canals, IN
earth and masonry, that colored water, dis
charged al the bottom, reached the surface
at distances VARYING from ten TO thirty times
the depth.
In natural water-courses, in which the beds
are always more or less irregular, the dis
turbance would be mucn greater. The result
is that the water at the surface of a running
stream does not remain there, and when II
leaves the surface il carries with il the needles
If ice, the specific gravity OF which differs
nut lltie from tllat u Tue water, Which, CJul-
bined with their small size, allows them to be
carried by the currents of water in almost
any direction. The converse effect takes
place in muddy streams The mud is ap
par ntly held in suspension, but is only pre-
vented from subsding by the constant inter
mixture of the different parts of the stream
hen the current ceases the mud sinks to the
bottom; the earthly particles composing it,
being heavier than water, would sink in still
water in times inversely proportional to their
size and specific gravity.
This, think, j. "A sati factory explanation
ot the manner in which the ice formed at the
surface finds its way to the bottom. Its adj
herence to the bottom, think is explained
by the phenomenon OF regulation, first OBJ
served py Faraday. He found that when the
wetted surfaces of two pieces of ice were
pressed together they troz- together, ana that
hi took place IN Ter water even when above
the freezing point. Prof Jas. d. Forbes
found that the same thing occurred by mere
contact, without pressure, and that ice would
become attached to other substances in a sim
liar manner. Regulation WAS observed by
these philosophers IN carefully arranged eX-
periments, with prepared surfaces fitting to-
gcther accurately, aud kept IN contact ouc-
emily long to allow the freezing together to
take place. In nature these favorable condi-
tons would seldom occur in the masses of ice
commonly observed; but we must admit, on
the evidences of the recorded experiments
that under particular circumstances pieces of
ice vii! freeze toy Their, OF adhere to other
substances, IN situations whore there can be
NJ at. tra ton of heat.
When piece OF ice. of considerable size
comes in contact, under water. with ice or
other substance, it would usually touch in an
area very small in proportion to its mass :;
and other forces acting upon it, and tending
to move it, would usually exceed the treez
my force and regulation would not take place.
In the minute needles formed at the surface
of the water. the tendency To adhere would
be much the same As in larger masses touch
ing At points only, while the external forces
acting upon them would be extremely small
in proportion, and regulation would of en-
occur. and of the immense number OF needles
If ice formed at the surface, enough would
adhere to produce the effect which we OBJ
serve, and call anchor ice The adherence
OF the ice to the bed of the stream or other
objects is always down stream from the place
where they are formed In large streams it
is frequently many miles below. A large
part of them do not become fixed, but AS they
come in contact with each other. regelate
and form spongy masses. often of consiiera-
BILE size, which drift along with the current,
and are often troublesome impediments to the
use of water-power. Water powers supplied
directly from ponds, or rivers or canals fro
zen over for long distance Immediately
above the places from which the water s
drawn. are not usually troubled with anchor
ice, which, as | have stated, requires open
wPter upstream for its formation"