Miscellaneous Inventions - 4

Miscellaneous Inventions - 4

 Edison's ore-separation work has been already fully described, but the story would hardly

be complete without a reference to similar work in gold extraction, dating back to the

Menlo Park days: "I got up a method," says Edison, "of separating placer gold by a dry

process, in which I could work economically ore as lean as five cents of gold to the cubic

yard. I had several car-loads of different placer sands sent to me and proved I could do it.

Some parties hearing I had succeeded in doing such a thing went to work and got hold of

what was known as the Ortiz mine grant, twelve miles from Santa Fe, New Mexico. This

mine, according to the reports of several mining engineers made in the last forty years,

was considered one of the richest placer deposits in the United States, and various

schemes had been put forward to bring water from the mountains forty miles away to

work those immense beds. The reports stated that the Mexicans had been panning gold

for a hundred years out of these deposits.

"These parties now made arrangements with the stockholders or owners of the grant, and

with me, to work the deposits by my process. As I had had some previous experience

with the statements of mining men, I concluded I would just send down a small plant and

prospect the field before putting up a large one. This I did, and I sent two of my

assistants, whom I could trust, down to this place to erect the plant; and started to sink

shafts fifty feet deep all over the area. We soon learned that the rich gravel, instead of

being spread over an area of three by seven miles, and rich from the grass roots down,

was spread over a space of about twenty-five acres, and that even this did not average

more than ten cents to the cubic yard. The whole placer would not give more than one

and one- quarter cents per cubic yard. As my business arrangements had not been very

perfectly made, I lost the usual amount."

Going to another extreme, we find Edison grappling with one of the biggest problems

known to the authorities of New York--the disposal of its heavy snows. It is needless to

say that witnessing the ordinary slow and costly procedure would put Edison on his

mettle. "One time when they had a snow blockade in New York I started to build a

machine with Batchelor--a big truck with a steam-engine and compressor on it. We

would run along the street, gather all the snow up in front of us, pass it into the

compressor, and deliver little blocks of ice behind us in the gutter, taking one- tenth the

room of the snow, and not inconveniencing anybody. We could thus take care of a snowstorm

by diminishing the bulk of material to be handled. The preliminary experiment we

made was dropped because we went into other things. The machine would go as fast as a

horse could walk."

Edison has always taken a keen interest in aerial flight, and has also experimented with

aeroplanes, his preference inclining to the helicopter type, as noted in the newspapers and

periodicals from time to time. The following statement from him refers to a type of

aeroplane of great novelty and ingenuity: "James Gordon Bennett came to me and asked

that I try some primary experiments to see if aerial navigation was feasible with `heavierthan-

air' machines. I got up a motor and put it on the scales and tried a large number of

different things and contrivances connected to the motor, to see how it would lighten

itself on the scales. I got some data and made up my mind that what was needed was a

very powerful engine for its weight, in small compass. So I conceived of an engine

employing guncotton. I took a lot of ticker paper tape, turned it into guncotton and got up

an engine with an arrangement whereby I could feed this gun- cotton strip into the

cylinder and explode it inside electrically. The feed took place between two copper rolls.

The copper kept the temperature down, so that it could only explode up to the point

where it was in contact with the feed rolls. It worked pretty well; but once the feed roll

didn't save it, and the flame went through and exploded the whole roll and kicked up such

a bad explosion I abandoned it. But the idea might be made to work."

Turning from the air to the earth, it is interesting to note that the introduction of the

underground Edison system in New York made an appeal to inventive ingenuity and that

one of the difficulties was met as follows: "When we first put the Pearl Street station in

operation, in New York, we had cast-iron junction- boxes at the intersections of all the

streets. One night, or about two o'clock in the morning, a policeman came in and said that

something had exploded at the corner of William and Nassau streets. I happened to be in

the station, and went out to see what it was. I found that the cover of the manhole,

weighing about 200 pounds, had entirely disappeared, but everything inside was intact. It

had even stripped some of the threads of the bolts, and we could never find that cover. I

concluded it was either leakage of gas into the manhole, or else the acid used in pickling

the casting had given off hydrogen, and air had leaked in, making an explosive mixture.

As this was a pretty serious problem, and as we had a good many of the manholes, it

worried me very much for fear that it would be repeated and the company might have to

pay a lot of damages, especially in districts like that around William and Nassau, where

there are a good many people about. If an explosion took place in the daytime it might lift

a few of them up. However, I got around the difficulty by putting a little bottle of

chloroform in each box, corked up, with a slight hole in the cork. The chloroform being

volatile and very heavy, settled in the box and displaced all the air. I have never heard of

an explosion in a manhole where this chloroform had been used. Carbon tetrachloride,

now made electrically at Niagara Falls, is very cheap and would be ideal for the purpose."