The CSO jackline plant — a steam-powered engineering marvel that drove California Star Oil Works' pumps via a network of cables stretching out over Pico Canyon.

Undated photograph; A.B. Perkins identifies Barbara Sitzman Cook as the photographer.

Note: Perkins called them jackplants. According to Nanette Lagasse Gaither, daughter of Pico oilman Frenchy Lagasse, they were called jackline plants.

Perkins in 1954:

The cables emanating from the jack plant that pumped the many wells wandered over the hill sides, turning corners with the aid of their butterflies. It didn't seem possible that a sober man could make such a hook-up — maybe they didn't. It isn't humanly possible to find proper words to describe a jack plant hook-up — call it a spider in the center of a huge rambling web, with pumping wells at each web tie-in, and the spider acting as an inhuman power source.

Perkins in 1962:

The darndest single spectacle of an old oil field was the jackplant. The more one watched it in operation, the more one wondered whoever had the nerve to suggest such an anomaly in the first place, and the patience to assemble it. There's quite a lot of pumping for production in oil fields. Today, nice little electrically operated, or gas operated engines are installed on an individual well and then forgotten until a sanding job, or the natural cussedness of mechanical objects, brings it to mind. Back in 1880, power was steam. So you tucked a firebox boiler back in the brush and set up your jackplant.

At best, it was a weird, designed to go in all directions at once. At worst, it was a horrible nightmare. You had a couple of eccentric plates, with about 18 holes, or eyelets in their rims, in which the cable hooks set. As they proceeded agitatedly through their pre-conceived, conflicting orbits, their cables, tightening and loosening, powered the well pumps. This CSO jackplant pumped about 15 wells on the CSO hill. [...] Problems in couterbalance were solved by suspending little wooden platforms, maybe rock loaded, as necessary. As the cables radiate wherever from the jackplant, it is a perfect example of "going all directions at once." Over on the PCO hill was another such plant.

Further reading:

Pico Canyon / Mentryville Index

The Pico Ghost Camp by Arthur B. Perkins, 1962.

The Story of Mentryville by Leon Worden, 1996 ff.