Survey number:      Owner:      Date of discovery:
". . . will work a revolution in gold mining throughout the country."



Wood's Mill, Then & Now, 1897-2011, View Looking N. The vintage drawing provided just enough info to identify the site, unchanged since the brief mis-adventure. Bart Parker stands atop the pad, doing what he does to perfection, providing scale. - William J. Warren © 2011

August 2, 1897:  “’Frank Cole, a prominent mining man of this city, has gone to Randsburg, where he will erect a dry concentrator plant of the Wood’s automatic pattern.” – The Herald

August 25, 1897:  “All the machinery for the Wood dry concentrator is on the ground here, and the work of getting it in position is proceeding rapidly. It is expected that the machine will be ready for work in about three weeks. The- plans of Mr. Wood, who is in Johannesburg superintending the erection of the plant, seem very feasible, and if his machines are as successful in practice as they give evidence of being in theory, a complete revolution in the treatment of dry ores may be looked for. ” – The Herald

August 29, 1897:  “Frank Cole of the dry concentrator works is spending a few days ln Los Angeles.” – The Herald

September 11, 1897: “WOOD’S AUTOMATIC DRY CONCENTRATOR MILL, JOHANNESBURG:  One of the leading properties of this camp and one which has marked attention, by reason of discoveries of ore of phenomenal richness, is the Alameda mine.  It adjoins on the east the townsite of Johannesburg, already one of the most active sections of the Rand district and which it is confidently expected will be the metropolis of it when the railway from Kramer, now being constructed, is completed.

“It is upon the property of the Alameda mine that the big reductions works are now being erected, at a cost exceeding, $20,000. and which, it is believed, will work a revolution in gold mining throughout the country.

“This plant is known as the Woods Automatic Dry Concentrator, and for the past month a large force of men have been engaged in its erection.  The starting up of this plant will, it is expected, take place about the middle of this month, and its first run of gold will be witnessed by prominent men from different part of the country, who are anxious to see how it works, when operated on a large scale.  While the plant has been erected for reducing the ores of the Alameda mine, it is the intention of the owners, to make test runs of other ores when desired.  The capacity of the plant is thirty tons per twenty-four hours.” -  The Los Angeles Daily Times

October 17, 1897:  “THE WOOD DRY CONCENTRATORr and, pulverizer connected therewith is actively at work on the Alameda property and working on ore from that mine. It is doing even better than Mr. Wood anticipated and solves the problem of dry reduction in desert mines of lowest grade ore.” – The Herald


“RANDSBURG, OCT.13—The Woods Automatic dry concentrator is a success, there seems to be no question about it.  For some weeks since its erection it has been ran in an experimental way, many small changes being made in time, bringing it to such a state of perfection that Mr. Woods the inventor felt justified in inviting Mojave men and others who were interested to be present this week, either Wednesday, Thursday, or Friday, and he would give a public test.  This he has done, and the concentrator has been at work, many people taking advantage of the invitation to be present and see for themselves.  The rock which is of a very low grade can be horned by any man who wishes, then the same kind of test made with the concentrates as they come from the little machines.  This of course will not tell it accurately as there will be much ran in the panning from the concentrates which carries gold, but not visible to the eye, but it will show enough free gold to convince the most skeptical that the machine do their work.  Assays made from the same rock and concentrates tell it accurately, and a number have been made by Wores of the sampling works.

Wood's Mill, Four Dry-Washers, Belts, Wheels, Ducts. ". . . run with as little noise as the ordinary sewing machine." As many moving parts as a Space Shuttle, no doubt in constant need of fiddling and fixing. - Los Angeles Times

“The plant as it stands today represents an outlay of $20,000 in round numbers.  It could be duplicated for less money but this is the first of the kind ever built, and may changes had to be made before it was a success.  Even now several changes are in contemplation,, but the principal remains unchanged.  The concentrators, four in number, each with a capacity of ten tons per day, are small compact little machines, taking up but little room, and when in operation run with as little noise as the ordinary sewing machine. They are beautiful in workmanship, and at first sight would seem to be too delicate for ordinary use, but they are so nicely adjusted and so carefully fitted for the work that there is neither jar nor friction noticeable as they perform their work.

“It descends to an endless revolving screen with slats at intervals of an inch or two, and in its passage the (latter) two currents of air meeting each other at right angles, creating a kind of a wave motion.  This air and the motion made by it separates the gold and the heavier portions from the dust and lighter matter, the former settling in the slots on the revolving screen and being deposited (attend) to the underside where they —————-by gravity or are detached by a light strike on the screen arranged automatically to fall about twenty times a minute as the screen travels by slowly and finally run off in a spout into a box and are the concentrates which contain the principal value.  The dust proper –is-s-(sucked?)-up and is collected in pipes and is carried to an outside building.  This contains some value in fine gold, but so fine that it must be handled very carefully in order to save it by any process.  The dirt and refuse leaves the machine at the rear and is carried out by an endless belt and dumped as worthless.

Foos Engine, 2-1/2 HP, 1900 - gasengine.farmcollector.com

“The concentrators are closely boxed in all the bearings and journals, being dust-proof, and every part when in motion, running at such slow speed that there is very little wear in any portion. The end and top being covered in glass instead of wood, a full view can be had of the inside at anytime.

“The building and room which contain the concentrators is a frame structure 18×36 feet in size and immediately adjoining on the east is the small engine room, 11×11 in which is located the two-horse power Foos gasoline engine, which furnished the power to run the concentrators, each concentrator requiring about one-eight of a horsepower to run it.

“On the west, and next adjoining the concentrator building, is located the mill for crushing the ore.  At the present a rotary mill is used, grinding the ore on the same principal as the ordinary coffee mill, run on ball bearings.  The capacity of the mill now in use is entirely inadequate to supply and keep running the four concentrators, and only two of them are used, the capacity of the mill not being sufficient to keep them running all the time.  As the principal point in interest was whether the concentrators would do the work claimed for them by the inventor, and as they seem to be all and more than ever claimed, the matter of crushing the rock being a secondary consideration, the procuring of more mills or a different kind of mill will remedy that defect.

“The pulp when turned out of the mill is at once elevated by a conveyer to the screen located in the second story and above the concentrators.  The screen at present is nine feet long and three feet wide, made of silk bolting cloth, with an endwise-shaking motion.  The first four feet have a ninety mesh and the balance sixty, with no intermediate.  The pulp coming through the ninety mesh is much finer and works better that the sixty mesh.  All that passes over the sixty is run into the tailings and back again to the mill, to be Ground over.  The space occupied and enclosed for the mill, conveyers and screen is 18×36 feet.


Wood's Mill - Foos Engine - Los Angeles Times

“On the west again is the engine-room.  This is a building 18×25, and here is located the twenty-five- horsepower Foos gasoline engine which furnishes the power for grinding the ore. This is a beautiful piece of machinery and when at work requires little or no attention.  Mr. Wood is quite enthusiastic over the workings of the engine and after examining others concluded that it was built on thoroughly scientific principals and would best do the work of the ordinary non-experienced miner.  It was set up and started by himself and Mr. Glore, neither having former experience, and so far has given satisfaction.  The fuel used is –her gasoline distillates.  The chloride building is 12×12 in which is collected the dust from the works, and stands entirely separate and away from the other buildings, only a large pipe leading into at the top.

“The ore dump is 36×150 feet.  The plant at its full running capacity, if the crusher was equal to the concentrators, will handle forty tons of ore per day.

“Some days ago a very close run was made on ore which assayed. $1.25 per ton, and a sample of the ore together with a sample of the concentrates, taken down to Charles R. Wores sampling works, and assays made, with the astounding result of ore $1.25 per ton and concentrates of $879.17 per ton, or a concentration of 760 to 1.  This was so surpassing, that for fear that some mistake had been made, a second test was made with the same results.  This is, of course, away beyond anything claimed for it by the inventor, but simply shows what the machines are capable of.

“Yesterday another test was made, some of the ground pulp being taken as it came from the mill, which assayed by the same party at $1.96 per ton, concentrates from the same after it came from the machine $87.80, with only a trace of gold in the tailings.  The last was a concentration of 41 to 1.  In each case it will be seen that the ore was of too low grade to have practical value but was taken from the Alameda mine dump simply to test the capacity of the concentrators for saving gold.

“Mr. F. W. Wood the inventor is here on the ground, and has had charge of everything connected with it from the beginning.  He is a New Haven Ct. man and an inventor of some note, having taken out 16 patents in his own name.  His principle tastes lying in the invention of labor saving machinery, some of his invention being in use in several of the pin machines now in operation.  He is a man of some capital, and has for a number of years spent some portion of each year in California.  Although not a miner, and not even a judge of gold-bearing rock, last winter when everyone was talking mines, he visited this county on his way to Mexico to look at some mining property there in the interests of some friends east, and stopping in Los Angeles met Charles Stilsen, who had experimented somewhat on a dry-washer.  Stilson suggested to him that the man who would invent a machine to save gold by the dry process would be a benefactor to this country. It gave him the idea, and after returning from Mexico he set to work. He was unacquainted with mines, mining machinery or anything connected with a mine, but was a machinist.  His first idea of how fine a job he had on his hands, and how delicate the conditions that he had to contend with were derived from an old miner who was examining some pulp he had, and took out a magnifying glass –something that nearly every miner has with him—and began studying it with that.  He then began to realize how small the particles of gold were that he was trying to save, and that it would require a machine as fine in workmanship.  He began work on the 19th of February, and has been continually at it ever since.  His first effort was to produce two currents—of air, which would form a wave motion, and, after several failures apparently succeeded.  He then made a crude, machine and experimented on some tailings worth about $5 per ton, and succeeded in showing up concentrates which assayed $58 per ton.  Then he knew he had the right principal, and went to work and built a first-class machine, which was inspected by many people in Los Angeles.

Woods Mill Stairs, Excavated Rise & Pad, Machinery. - Los Angeles Times

“Up to this time Mr. Wood has borne all expenses and experimented entirely on his own capital.  Believing it now to be a success he organized the Wood Automatic Dry Concentrator Company, with a capital of $100,000, and J. M. Hale, the dry-goods man and an old friend Charles Stilson, Frank Cole, and H. G. Glore and himself (F. W. Wood) as the incorporates.  They now propose to manufacture these machines in Los Angeles, and put them on the market.  This one now in operation is solely for the purpose of giving them a thorough test and absolutely demonstrating from actual trial that they will do the work claimed for them.  Having heard about the Rand mining district and that there was much low grade ore there, which owing to the conditions of locality, scarcity of water and fuel, could not be worked with the stamp mill or any other known device for milling ores, at a profit, and, in fact were absolutely worthless unless some cheaper method was devised, sent one of the incorporators, Mr. Frank Cole, up here to investigate.  On his report the company concluded to come to Johannesburg and locate on the Alameda mine, just northeast of town.  The valuable plant today in successful operation is the outcome of that resolution.

Wood's Mill Then/Now, 1897-2011, (View: N). Difficult to see, obscured by wind-blown in-fill, a sharp cut has been made in the layered bedrock, just under the stairs at the left. The stairs at the right conform perfectly to the excavation, access road just above and behind. The waste dump at the upper left is part of the Alameda Mine, host to the Wood's revolutionary but short lived experiment. So 'done' were the experimenters that they walked away and let the buildings rot in place, for the wind & scavengers to remove, the excavations unchanged. - William J. Warren © 2011

“Something of the kind having often been tried before, with failure as the result, led many to doubt the success of the venture.  All wished it to succeed, as no single thing is so important to the camp.  Thousands of tones of low-grade ore, formerly absolutely worthless have now a value; it is as though something was created out of nothing.  While there is no question but what the best results can be had by running a number of machines together as one plant, a little profit being made from each, and the expense of running being much lessened, yet if that is not always practicable the man who owns a mine of low-grade ore nearly always found in larger veins than is the higher grades, can buy one of these machines and a small engine to crush his rock, and also furnish power for the concentrator, as it is not at all necessary to have a separate engine for this purpose, put it upon his mine  wherever located and grind out his own fortune.  After reducing it to a certain extent he can again put it through the machine, and his expenses for transportation and working of his concentrator will be brought to a minimum.

Wood Dry Concentrator Patent Synopsis, 1899. Dry Concentrator Patent, The Colliery Engineer Co. Mines & Minerals, Volume XX, August 1899, to July, 1900. Frederick W. Wood was not easily discouraged, filing for a Patent in August, 1897, shortly before the six month excitement so artfully described above. Patent issued on September 19, 1899. One can only surmise that the Patent Examiner was overwhelmed by the shear volume of scientific principles incorporated, between the blowing, beating, sucking, swinging, floating, pivoting, hopping, and last-but-not-least: adjusting. Both Inventor & Examiner appear equally indifferent to whether it actually worked. Much stock is placed on the values contained in the dust, brushing off the more complex challenge of separating the microscopic particles of gold from the other dust. Another problem for another day: ". . . and subsequently treated in some suitable apparatus." Equally off the radar is any provision for breaking the (low grade) feed stock, making the dust. A poster perfect demonstration of the Rube Goldburg School of Engineering in action! (WJW 05/11) - Google Book Search

“The machines are simple in construction, and easy to understand, after being properly arranged to begin with. Three principal things are to be looked after: The feed, to determine at what rate it is going through, whether at the rate of ten or more tons per day; the regulation of the air in ache (?) current and the specific gravity to determine its value. These can all be learned by any practical miner in a short time.

“Up to today no rock of higher grade than $4 per ton has been tried.  While it is claimed that it will work equally well in high as well as low grade ores, the concentration not being so great, yet, as will be seen by practical men, its chief value and merit will always be to work ores no other machine can handle.

“Mr. Wood is enthusiastic about the future of this mining camp, and proposes as soon as he gets this concentrator off his hands to make some investments, and become identified with the camp.  Future runs will be carefully noted and a full and accurate account will be given in future issues of the Times.” -  The Los Angeles Daily Times


November 4, 1897: “J. M. HALE, the dry goods man, and C. A. Stilson of Los Angeles, are visiting and inspecting the district.  These gentlemen are both members of the Woods Dry Concentrator Company.  The concentrator is now running steadily one ore from the G. B.  A small lot was put through for Mr. Vendervoort and partner with very satisfactory results.  An assay from the ore gave $25 per ton,  An assay from the concentrates gave $2186 per ton, while the tailings showed $1.25 per ton.”  – The Los Angeles Daily Times


February 21, 1898: “F. W. WOOD, the dry concentrator man, will be here on the doth with a new crusher, new screens and dryer, and will again start up the concentrator.  The company has been reorganized, several of the old members going out and new men taking their places.  Mr. Waterman, son of ex-governor, is now interested in the plant.”  – The Los Angeles Daily Time

March 7, 1898: “MR. WOOD of the Dry Concentrator is making some changes in the machinery of that plant, putting in a new crusher and other improvements and proposes in a few days to start up again.” -  The Los Angeles Daily Times

October 31, 1897:  WOOD’S AUTOMATIC DRY CONCENTRATOR–As stated above, this plant is situated on the Alameda Company’s ground. It is claimed to be an improvement on all other concentrators, the fundamental basis of the invention being (as F. W. Wood, the Ingenious inventor describes it) the reaction of the vibration of air or “the wave motion.” The great advantage claimed by Mr. Wood is that it will save a large percentage of concentrates than are saved by any other known process. The many tests made, commencing with the one made in Los Angeles several months ago and witnessed by the writer, have been so uniformly and completely satisfactory that reference thereto in detail is unnecessary. The machines now being manufactured have a capacity of fifteen tons of ore each per day of twenty-four hours and can be operated with one-eighth the power used in other machines to accomplish the same results, making it one of the cheapest, if not the cheapest, concentrators in America. Where mines are situated a long distance from a mill, smelter or cyanide plant, and where water is scarce, this concentrator is invaluable and it will be a great factor in the development of such mining property. The number of tons of ore that can be concentrated into one ton by the Wood process is, of course, dependent on the proportion of concentrates in the ore. In some cases thirty tons of ore have been reduced to one ton by this machine, which is a remarkable showing. Base ores are successfully handled as well us free-milling ores. The concentrates can be extracted from the base ores on the spot where they are mined, thereby avoiding the cost of transportation on the unproductive part of the ore. In connection with the Wood concentrator is a quartz crusher, which also has a very important advantage in a dry country, as all the water necessary to run a plant of this kind, with a capacity of thirty tons per day, is about one ordinary barrel, using a gasoline engine. The necessary power to crush and concentrate the ore in this plant is furnished by one 25-horse power. The crusher Is not giving perfect satisfaction, and is another man’s invention, hence Mr. Wood is investigating the merits of other crushers and is confident that he will soon have the crushing department in as successful working order as the concentrator. Those associated with Mr. Wood In the ownership of the Invention and machines are J. M. Hale of the firm of J. M. Hale & Co. of Los Angeles, Frank Cole, William Cole and C. C. Gibbons. Mr. Wood comes from New Haven, Conn., and has devoted almost his entire life from early boyhood to the invention of automatic machinery. He is the Inventor of a pin machine that makes the pin, puts it in the paper, folds the paper and prints the name of the firm on the back of the fold. He is a man of considerable means, and has for a number of years past regularly spent his winters in Southern California. He claims that his invention of this automatic concentrator is the most valuable of any he is the author of. His friends claim for him that he can do by machinery anything that can be done by hand.” – The Herald

September 20, 1899: WASHINGTON. Sept. 10. — Pacific Coast patents were granted to-day as follows: California— Frederick W. Wood, Los Angeles, dry concentrator. A. J. Petter, Randsburg, stamp and roller crusher and pulverizer….” — San Francisco Call

AUTHOR’S NOTE, (WJW 11/2010):

Mining, Milling & Inventing go hand & glove, overcoming unforeseen obstacles in complicated ore, water & air handling processes, invariably improvised from ‘recycled’ mining & auto parts, the obligatory yard full of broken equipment to cannibalize.

All involve some kind of Rube Goldberg mechanical contraption(s), rarely operating for more than hours at a time without something breaking down or running out of one vital commodity or another, such as: paying dirt / ore,  gas / oil, beans / credit.

The Wood’s Concentrator is a ‘poster-kid’ example, and it went down the usual path,  a slow-motion collision course with the laws of economics and/or physics.  Particularly troublesome is the theory that energy cannot be created from nothing.

The Times writer is to be applauded  for the courtly restraint and bone-dry wit (typical of the Victorian era) in reporting the facts and the reasons such schemes had the odds stacked against them.  He clearly writes from knowledge & experience and for the entertainment of his many readers (who had ‘Seen the Elephant’ of mining).  His assay ‘figures’ must have produced howls of laughter.


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