First developed in the goldfields of the state of Georgia, the rocker was an important gold mining tool. At the dawn of the California gold rush, the rocker box, also known as a cradle, was perhaps the most widely used gold prospecting piece of equipment. For a time it was perhaps even more important than the gold platter. This was mainly because the miner could make himself a rocking chair in the field from lumber cut in the forest. They are also easy to transport. Rocker boxes were also popular during the Klondike Gold Rush for working hillside placers that were high above streams.
The ‘seesaw’ is a box with a hopper of about 3 to 4 feet. long and 1 to 2 ft. wide, inclined like a cradle, and is mounted on semicircular pieces of wood and worked by a handle to give it lateral movement; and it is also inclined to carry the material to the lower end, which is open. At the top is a small removable hopper with a 1/2 in. perforated sheet iron bottom. Holes Beneath the hopper is a canvas platform or tray that slopes toward the head of the box but does not touch either end of the hopper-box. Several wooden rifles are placed across the box. The material is fed into the hopper and sieved with water poured over it; the lighter material is brought last, while the rifles in the box catch the gold and magnetic sand. This concentrate is cleaned and broken at the end of the operation. The seesaw is used for the same type of work as the gold pan, as it is primarily a prospecting tool. One man can wash 3 to 5 times as many yards as he can with the gold pan, and the use of the seesaw removes much of the back-breaking stress of the continuous pan. On the other hand, the easy mobility of the dish as a prospecting device is lost.
So why would a modern day prospector be interested in building his own rocker box? The primary use of a gold rocker is for mining small deposits where water is scarce. It’s not really a desert device and it uses a significant amount of water, but not as much as a floodgate. In a rock, gravel requires approximately three times its own weight of water to wash it away. So perhaps the best use is in very low water streams and waterways, where there is some water, but not enough to run a gate box. If there is enough running water to operate a gate, a gate is faster and easier to operate than a seesaw. The seesaw is only a primitive machine, having a capacity one-fifth that of the gate box, but because it is cheap, requires little water, and saves a high percentage of raw gold, the seesaw will continue to be used in many districts.
The operation of a seesaw consists of shoveling gravel onto a screen or grizzly, pouring water over it from a bucket, and at the same time giving the device a rocking motion back and forth. The grizzly retains all the large stones, which are removed by hand when they have been washed. The operator briefly examines the large rock to ensure that no large nuggets or gold specimens are thrown away. The cradle should be placed at an angle while working, and under the influence of continuous rocking from side to side, the dirt quickly disintegrates, passes through the hopper grate, and the water and undersize fall on the canvas platform that Save most of the gold and place the rest at the head end of the trough. From the platform it is conveyed to the inboard end of the cradle floor (the gate box-like section of the outrigger), from where it flows over the rapids or bars and out the mouth. Rifles, tarps, blankets, corduroy, burlap, or cocoa mats with expanded metal have been used to cover the bottom of the trough and have all had varying degrees of success in saving gold. The combination of cocoa mats covered with expanded metal laths has proven to be quite effective for most gravels. The frequency of cleaning depends on the richness and character of the gravel, but cleanings are usually necessary two to three times a day. The hopper is first removed, then the apron is slipped off and washed in a bucket or tub containing clean water, and finally the gold is scooped up behind the rifle bars and filtered.
The rocking motion used should be enough to keep the gravel stirred, allowing the gold to settle, but too vigorous a motion will cause a loss of gold. The gravel bed should shift slightly with each movement and should be evenly distributed along the length of the gutter. Generally speaking, rocker is not known for its ability to save fine gold, but with careful and expert handling, decent fine gold recoveries can be achieved. Tailings from both the beams and gate boxes should be filtered occasionally to check for gold losses. When gold is found near the bottom end of the beam or gate box, the possibility of leakage should be investigated.
Because there is no “correct” design for a rocker box, I’m not actually presenting specific plans, but on my website I give you the information you need to plan, design, and build your own rocker box if that’s what you need. That decides. do. My recommended design for a seesaw is to start by building a gate box that is 40 inches long, 16 inches wide at the bottom, sloping like a cradle, and with seesaws at each end. The hopper would be 16 inches square and 6 inches deep, with a sheet steel bottom drilled with 1/2-inch holes. This hopper box should be designed so that it can be removed for cleaning. A lightweight canvas-covered frame stretches under the hopper, forming a rifle. Quick squares of wood or steel are placed on the bottom of the sluice portion of the seesaw. Curved feet are placed under the gate portion of the box to allow it to rock back and forth. Historically, rocking chairs are constructed of wood, just as the early gold prospectors built them. However, there is no reason why you can’t build a rocker out of heavy-gauge, heavy-duty sheet aluminum. It would be much lighter than the wooden version. Remember that wood also absorbs water, and water-soaked wood is much heavier than dry wood.