Monday, November 30, 2009

Nevada City walking tour: Pelton wheel at George Allan's Foundry

Nevada City in California, located northwest of Sacramento in the Sierra Nevada foothills, is the home town of the Pelton wheel. Walking through the historical quarters of Nevada City, one can find tools and artifacts, including Pelton wheels, from the time of the mining boom displayed at various sites. One such wheel stands in front of the original brick building of Allan's Machine Shop, which was founded in 1856 and was in continuous usage as a foundry for over 110 years. The famous wheels with the double-cupped buckets, designed by Lester A. Pelton of Camptonville and Nevada City, were first manufactured here. A plaque (placed on May 11, 1994) explains:
The Pelton water wheel, first commercially manufactured here at George Allan's Foundry & Machine Works in 1879, was a major advancement in water power utilization and greatly advanced hard-rock mining. Its unique feature was a series of paired buckets, shaped like bowls of spoons and separated by a splitter, that divided the incoming water jets into two parts. By the late 1800s, Pelton wheels were providing energy to operate industrial machinery throughout the world. In 1888, Lester Pelton moved his business to San Francisco, but granted continuing manufacturing rights to Allan's Foundry, where the wheels were manufactured into the early 1900s, when most local mines shifted to electric power.

Thursday, November 5, 2009

Owl watching at Berkeley's waterfront

The ground squirrels and squirrel holes in Berkeley's Cesar Chavez Park—many next to the trails— are hard to miss. Some holes are abandoned by squirrels, but are used by burrowing owls (Speotyto cunicularia) as resting place. These owls are known to dig burrow nest in open fields, but take advantage if they find some ready-made nests. I am not aware of any predator-prey relationship between squirrels and owls and assume that the burrowing owls feel well-protected here. According to a posted information sheet, burrowing owls hunt and eat crickets, beetles, small rodents, lizards, and crayfish. Since burrowing owls are active during night and day they can easily be watched during the day: These small brown birds (8 to 10 inches tall) are spotted with white. There head is rounded and lacks ear tufts. While you are watching them, they probably watch you with their yellow eyes.

Also see Burrowing owls in the northwest corner of Berkeley's Cesar Chavez Park.

Wednesday, November 4, 2009

Burrowing owls in the northeast corner of Berkeley's Cesar Chavez Park

The Cesar Chavez Park is a recreational area at Berkeley's waterfront. In fact, this site is a former landfill in the San Francisco Bay. Now, green grasslands belong to its main features. The park is a playground for humans, dogs and squirrels. But more surprising, some Western Burrowing Owls (Speotyto cunicularia) selected sections of the park as their habitat, where they stay over winter—from October to April. Burrowing owls typically “play” and hunt by day and you can easily spot them from the trail during a day-walk. So it was in 2004, as The Berkeley Daily Planet reported, and so it happened again the following winter seasons.
In a joint project, The Golden Gate Audubon Society, The Shorebird Park Nature Center, and the Berkeley Marina of the City of Berkeley are monitoring arrival and well-doing of the owls. In the northeast corner of the Park a small, “fenced-off” area along the shoreline trail has been created for their protection.