More exploration on this week's Sunday cycle trip along the canal.
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| Flood arch under Leinster Aqueduct. © Eugene Brennan |
I
was going to go as far as Digby Bridge, but it was 6.30 on a really
gloomy day and I wanted to get back to Kilcullen before it got too dark,
so I'm going to have a better look at this structure at a later date.
This is the underside of the Leinster Aqueduct, constructed in 1783,
which carries the canal over the River Liffey. There seem to be several
of what look like flood arches at this section, quite high up on the
river bank away from the main arches. The New Bridge at Carnalway (as
it's described on the c. 1837 OSI first edition map, because there's an
older 17th century bridge upstream on the Harristown estate) also has
one or more flood arches (I think) on the northern side of the bridge,
but one of these is described as a tunnel on the later 25" c. 1900 map.
This may have been an access route to the corn mill shown on the first
edition map. The corn mill and mill pond seem to have disappeared by the
time the 25" map was created.
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| New bridge over the River Liffey at Carnalway. shown on the c. 1837 first edition 6" OSI amp. Map image courtesy OSI (Tailte Éireann) |
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| Bridge over River Liffey at Carnalway. The corn mill has disappeared by the time the 25" map was drafted. Map image courtesy OSI (Tailte Éireann) |
19th Century Mills in Kilcullen
On
the subject of mills, in addition to the mill at New Abbey and in the
centre of the town, there was also one located in the fields between The
Stray Inn/The Mill pub and the Green Avenue, also with a small mill
pond to store water (the 19th century equivalent of a battery storage
facility). This was fed by a mill race off the Mill Stream, splitting
from the stream inside the grounds of Gilltown estate. Strangely, the New
Abbey mill has no mill pond shown on the map, possibly because it no
longer existed by the time the 1837 map was drafted. The area around the
Mill Stream south of the road bridge is quite flat, so perhaps that
acted as a natural reservoir to hold water, with flow controlled by a
sluice further downstream. Alternatively If flow was sufficient and
constant on the stream, maybe a mill pond wasn't necessary? The feed to
this mill passed through an arched culvert under the road, a short
distance south of the bend at the entrance to the cemetery. The mill was
located just east of the wall around the cemetery, the ruin in the
field possibly being part of the structure. There was actually what
looked like a small small weir (although it may just have been a change
in the level of the stream bed), visible on the south side of the bridge
in the 70s. From what I can remember this was only around a foot tall
(see photo from 1983 below), so possibly it was the remains of a taller
structure. There was also a saw mill on the Gilltown estate and the
current lake was possibly the mill pond that supplied water to this.
Maybe someone knows the history of this? It's shown on the c. 1900 map.
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| The Mill Stream, Kilcullen, south of the bridge on the New Abbey Road. The photo was taken in 1983. © Eugene Brennan |
What were mill ponds for?
A
mill pond acts like a buffer, analogous to the tank on an air
compressor, the latter storing energy so that it can be released in
large dollops when necessary, greater than a compressor pump could
deliver on it's own. Anyone who worked in Renley Engineering may
remember the flywheel on a punching machine, which had the same
function. The advantage of a mill pond is that it can store water from a
stream with a relatively low flow rate, even during the night, and a
sluice gate can be opened to release a larger flow when required,
greater than a stream itself could source. A weir has a similar
function, backing water up behind a barrier, often on a river. A weir
however raises water level so that the water gains potential energy
because of its height. Some mills don't seem to have had weirs. Instead,
a mill race carried water from a point further and often a long
distance upstream where the water level was at a higher elevation.
You can view old maps on the OSI's Irish Townland and Historical Map Viewer here:
Map images courtesy OSI (Tailte Éireann)