It looks to me like the bridge was built to do exactly what it is
doing,which is to hold a turbine pump. It's plenty stout, so maybe it
originally held an engine to run the turbine, which has been replaced
with an electric motor. The rack in the center is to pull the pump
during the winter to avoid freeze or flood damage. The canal is an
irrigation canal. Follow it toward the river and you will find a
headgate and probably a small diversion dam to channel water into the
Thanks for all the input, everybody. I've sent an inquiry to the
local historical society. I'd love to know when this was built. WPA
project? Did they have this technology when my family owned the farm
(1903ish to 1925ish)? I'll be in the area again for Memorial Day
Weekend to decorate the graves of family members and will try to take
more pictures then. Didn't get a single one straight across the
traveling path of the bridge!
On Wed, 26 May 2010 07:02:43 -0700, MNRebecca wrote:
Courtesy of Google, it looks like what's referred to as a pony truss
bridge. In the early 1900s, they were the cheapest bridge design for
short spans and a number of companies made them. By the time the
depression and WWII were over, highway departments had moved on to newer
designs (than steel truss). Example of one still in use:
Consider the possibility that "your" bridge was repurposed from its
original use/location. As those bridges were phased out, some were
probably free for the taking.
But the best way to solve the mystery is to inquire locally this weekend.
I am LOVING the idea that the reason my tough ol' great great grandma
had $5,000 to give each grandchild in the 1920s (money that
disappeared in 1929, of course) was because she looked out over the
tributary ditch one day and said, "You know, if I took one of those
bridges they're giving away and put it across the ditch, I could rig
up a pumping system to better irrigate my fields!" But would there
have been ditches WITHOUT such bridges in the first place? How did
you get the water out of the ditch and onto the field without the
Quite likely. In most of the world where ditch irrigation is used no
pump is involved. Methods of getting water from the ditch to the field
generally require the ditch water level to be higher than the bottoms
of the furrows in the field. To get water across the ditch bank there
are siphon tubes, removable barriers as simple as a plank, etc.
or, if they used a pump initially at ground level, it would be less
efficient since it had to do a lot of "sucking". With the bridge in place,
they could easily put the pump in the water, driven by a shaft from the
motor on the bridge.
I concur that the bridge was probably reused from some other purpose.
On Wed, 26 May 2010 12:02:52 -0700, MNRebecca wrote:
You mentioned in your op that the ditch is along/on the property line.
It would seem that to irrigate farm A, it would have been simpler to put
the pump on the bank and run an intake pipe up from the ditch. But say
both farm A and farm B wanted to irrigate. The bridge and a single pump
might have been the more frugal solution.
(Yes, I know that's a stretch.)
Flood irrigation. A system where you divert the stream into a series of
irrigation ditches that water the fields passively without the use of
pumps. In Phoenix AZ, some people have their lawns done this way
instead of using city water. The system was developed by the Anasazi
who no longer inhabit the region. The only down side to that are the
stinking minnows that wind up in the yards.
Of course there would have been. Watering can be moved out of the ditch by
hand very easily using a simple syphon method and that is common enough even
today. See pic on this cite:
only if you turn the whole world on its head. Siphoning from a lower to a
higher point sounds like a perpetual motion machine. Are you trolling?
I checked by doing a lookup at groups.google.com; iirc the first post
they have is Aug, 2000. Didn't look up my first post but it was in early
1996 ... even more depressing.
To now go completely off topic, do you know how much damage the volcanic
ash did where Janet lives?
She's posted to say that there were small pools of white water on her
windowsills and it was only when touched that she realised it was ash on the
top. She's also written about how the sky looks but other than that, I
dont' think it really had a huge impact on her circs.
I've also been posting in misc.rural for years. But I've not noticed this
'wallace' poster there before which is why I had a chuckle at the troll
comment (who's the troll: the one who's posted for years or a suddenly new
name?). Wallace can't be very 'rural' if s/he has not seen the way
irrigation is used as per the pic in the cite I gave. Mind you many of the
posters in misc.rural aren't what I'd call 'rural'.
Siphon tubes have pretty much disappeared in my part of the U.S.
It's just too much work and the land has to be fairly flat. We had a
few when I was a kid. One thing I remember was the varmints digging and
causing leaks in the ditch.
I had relatives in Idaho who used a lot of siphon tubes. I think
the water came from the Snake River. They had some tubes as large as 4"
diameter for pasture irrigation.
Pivot irrigation is by far the most common. Some farmers are trying
subsurface irrigation. Gated pipe is still fairly common.
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