The Miracles of Light (Dec, 1936)
The Miracles of Light
By Charles Morrow Wilson
THEY were having a light dinner party. Samuel G. Hibben, illumination engineer and authority on light and responses to light, was host. Food, drink, and chef were the best that money could buy. There were musicians, gay storytellers and all the trimmings.
The host had even arranged special lighting for the evening. Instead of ordinary clear or frosted lamp bulbs, he substituted especially designed filter lamps which cut out all the ordinary spectrum . of colors except greens and reds.
Guests strolled in to the table, hale, hearty and merry. Then they began to notice that their eyes were deceiving them. Delicious steaks were whitish gray. Celery was gaudy pink. Milk appeared blood red. Salads were bright blue. Lemons became oranges. Coffee changed to pale yellow. Fresh green peas appeared black. Peanuts seemed bright red.
The food and the cooking were perfect, but the broken-spectrum lights played havoc with established senses of color and taste. Therefore the dinner party wasn’t especially enjoyable. Most of the guests ate almost nothing. Several left the table prematurely, and two became violently ill after dinner because of “confused eye responses.”
The dinner party was not altogether a practical joke. It was a demonstration of the effect of light, not only upon the sense of sight, but upon related senses of taste, smell and touch. It was a pertinent example of the underlying theory of modern light researchâ€”that over and above its abstract physical qualities, today’s challenge of light is a challenge of individual application and individual reactions to light on the parts of the various orders of life. In order to make plants grow better, we must literally learn how the world looks to a plant. To use light as a defense against insects or bacteria, we must learn something of how the world looks to insects and bacteria. Such learning is a tremendous job.
Today men of light are learning, and therefore we see spectacular progress in the classification and use of lights. Outstanding among these steps of progress are sterilization of bacteria and harmful microorganisms by means of the lethal or death ray; trapping of harmful moths and night-flying insects by use of the correct length of light waves; destruction of termites and borers by light; further perfection of the X-ray; better propagation of desirable plants and seed, and destruction of undesirable plants and seeds by the use of light.
Most of our new findings in light remain in the world of the unseen. We see only a small octave of light. The best human eye in the world is at least half blind.
Light is measured in terms of angstroms â€”linear distance between crests of light waves, which so far as we know are shaped very much like water waves. Nobody ever saw an angstrom. Here’s why. Take a medium dull pencil and make a mark on a piece of paper. The width of this mark is probably about one millimeterâ€”roughly one twenty-fifth of an inch. The angstrom is one ten-millionth
of one millimeter. The human eye sees only in terms of light waves between 4,000 and 8,000 angstroms in length. Any wave longer than 8,000 passes out of the range of our visibility, begins to be registered by our nerve ends, and therefore we call it heat. Light waves of around 3,300 angstroms, though below the bounds of our spectrum, are the much talked about ultraviolet rays which give becoming sun tans. The X-ray, as short as ten angstroms, is the shortest light wave known to science. Between the X-ray and the ultraviolet are the more recently segregated lethal or “death” rays, those between 2,000 and 3,000 angstroms in length. Use of the lethal ray as a potential and powerful agency of destruction today offers some of the most thrilling chapters in the whole thrilling subject of light. Scientifically speaking, the lethal ray is just now being born, and its birth is a tough break for little bugs. Bacteria or microorganisms are its logical prey. In terms of human beings or large animal specie the lethal ray is not yet a “death ray.” The actual penetration of the lethal ray remains extremely slight. Under present classification it couldn’t dig far enough into a human body to reach a vital organ, though it can cause a malignant skin burn. But it is a dealer of speedy death to bacteria and microorganisms.
For every animal that breathes there are unseen billions of bacteria. Much of this vast bacterial life is helpful to man, in fact indispensable. Yet the bacterial little bugs sometimes get through their vigilance. They may drop down from the air. They may hover in particles of sponge or rubber. Though ordinary flesh wounds can be pretty well cleaned with liquid sterilizers, a surgeon opening a human abdomen can’t “germ-proof” this kind of wound by pouring in a pint or two of liquid sterilizer. That would probably be as hard on the patient as on the bacteria.
Dr. Hibben and his staff of light students, engineers, pathologists and medical researchers, visualize a device whereby every type of wound can be cleansed of all bacteria by means of lethal-ray light. They have actually invented and patented this equipment. The Westinghouse Lamp company recently shipped out 100 lethal-ray sterilizers. Each machine goes to a prominent physician or surgeon for experimental use. Thus far the equipment isn’t safe for the amateur to use. The mechanical challenge is primarily one of producing a bulb with glass filters so extremely thin that the glass will tend to center the power of the tiny waves. A bubble process has been devised which reduces the thickness of the glass to about one-thirty-thousandths of an inch. In addition to killing microorganisms on flesh surfaces the lethal rays combat certain skin ailments such as ringworm and “athlete’s foot,” apparently caused by microorganisms that are first cousins to ordinary bread molds.
That’s the human side of the lethal-ray story. The housekeeping side is but a short step away. Today we see the arrival of lethal-ray equipment to give the permanent knockout to every organism that may lurk on dinner plates, glasses, or cups. Most of these microorganisms are comparatively harmless. Yet if you and I were shown enlargements of the infinitesimal plant and animal life that settles upon the cleanest of chinaware wholly without invitation, we would probably indulge in quite a number of fasts. The New York City Board of Health now has under consideration eradiation equipment which sterilizes restaurant, hotel, and fountain equipment by lethal waves of light.
Already the death ray is beginning to take a place in commercial meat-packing and canning. Every day, microorganisms too small to be seen cause tremendous spoilage loss of foods. Therefore several commercial packers are beginning to use lethal light rays to sterilize and pre-insure the keeping qualities of their products. This attainment grew directly out of research on ways to sterilize refrigerators. The answer seems to be that foods should be made sterile before entering a refrigerator. Glass or earthenware containers can be pretty well sterilized with boiling water. Frequently containers made of wood, pulps, or plant-fiber products cannot stand the boiling water treatment and demand sterilization by eradiation.
Molds, too, are among the most costly of all weed pests, ruining uncounted millions in food products every year. Mold ravages have been seriously aggravated by entry of the pre-sliced loaves of bread. Careful wrapping and storage are not always a safeguard. Sometimes mold spores get on mixing machinery or knife blades and become planted in the bread before it is wrapped. Today, at least one great chain bakery is beginning to use lethal-ray vaccination against molds in all of its products, including fruit cakes and plum puddings.
It is possible, even probable, that death-ray equipment will be available for home use within five years, or sooner. The equipment is still comparatively expensive, and if handled carelessly is extremely dangerous to human skin and eyesight. The inventors and developers make the friendly suggestion that if you wish to experiment with the lethal ray, you better watch your step.
So far we have been talking of extremely small light waves that destroy extremely small bugs. Let’s consider larger waves that attract larger bugs. Use of lights for trapping night-flying beetles and moths gains increasing importance since we find that many of our gravest insect pests are readily attracted by lights which are within range of human visibility. On a summer night one may now see light traps in lawns and gardens, serving not only for the good of grass and gardens, but also for the comfort of people. Orchardists are learning that light traps are the most effective control of codling moths, foremost enemy to apples, and lawn tenders are finding that light is equally effective for trapping the Asiatic beetle which eats grass and foliage, while its larvae destroy roots.
The light trap is simple. It can be merely a lamp, either kerosene or electric, placed above a pan of kerosene or beside some leaves or strands of sticky flypaper. Moths and beetles fly to the light and eventually skid down into the kerosene or tumble against the flypaper. There also are light traps on the market.
Insect trapping with light becomes more important as insect damage becomes more serious. The world grows smaller as transportation becomes faster and bugs get around quicker. The Asiatic beetle, which probably accounts for the brown spots on your lawn, is said to have reached us by way of a shipment of oriental iris bulbs. This bug,, one of the most serious menaces of our time, is one of the most easily trapped by light. An air liner from Cuba to Florida brings a dozen malarial mosquitoes as unnoticed stowaways. Left to their own devices many of our worst insect pests wouldn’t spread far. But when the chance comes for an insect to hop a ride, that’s a different story.
The real importance of light trapping of the night flyers lies in local control or defense against localized insect plagues and is an excellent supplement for quarantining, spraying and other forms of necessary warfare against our fiercest competitor, the bug. Light trapping came into popularity as a by-product of the nation-wide craze for miniature golf courses. People went at night to play on these brightly lighted courses. Lights drew bugs, and bugs annoyed customers. Operators demanded light traps and got them. Then it became evident that many of the bugs caught in these traps were miners of crops, lawns, and gardens.
To trap any sort of game, one must know something about the habits and senses of that game. Unquestionably insect eyes respond differently to light than ours do. To visualize just how the world looks to a bug is a hard job. But this is exactly what light engineers and entomologists, aided and coordinated by the department of agriculture, are trying to do. Progress is promising.
Many insects are attracted by light waves which we can see. Asiatic beetles or codling moths can be trapped with an ordinary clear lamp. Others, like the mosquito, are actually repelled by lights that are within the range of human visibility. Others, like the grasshopper, evidently see by a light which we can’t see at all. But within limits of our own sight and color spectrum, the greatest number of night-flying insects seem most attracted by bluish-white lights. Frequently a delicate blue bulb will lure twice as many bugs and moths to a trap as a plain clear bulb. Red lights have little drawing power since insect eyes seem blind to red and green. A red bulb will usually draw less than half as many as a clear bulb, while yellow or golden lights often repel. Bees, hornets, and wasps swarm about fine blue lights, and most other insects respond most easily to the fine blues and violets, which are the lower edge of the human spectrum. There is every reason to believe that ultraviolet light, ranging from colors faintly visible to the human eye, through the shorter wave lengths on down to 3,300 angstroms, the sun tan light, is most effective for drawing insects.
Colors and temperature reactions are also important. We don’t know much about the thermodynamics of insect life, but we are learning something of color responses of the lower orders. In this connection the recent introduction of electrical illuminations through gases is important. Sunlight, as we know it, is a gas-filtered light, but the filtration provided by the atmosphere of the earth, and perhaps by oxygen clouds which surround the sun, allows a comparatively solid wall of color spectrum. On the other hand we now know certain gases can eliminate large portions of the color spectrum of light, blot out some colors entirely and therefore intensify others. The Neon tube light for signs is a good commercial demonstration of this principle. Light filtered through helium, for example, is cream-pink to the eye; through argon, vivid purple; through thallium, vivid green. Mercury vapor reduces the spectrum to red, yellow, green, blue.
Quite possibly this new conception of “gas light” may have a profound place in insect control through color response and allure. In any case light would seem the most logical control element for harmful insect and bacterial life. The field of light-trapping, like the infinite field of light study and experiment, is wide open for the amateur, for the home mechanic and for the original observer.
In viewing the new magic of light, we should notice some new findings in the life-giving relationship between life and leaf, since in this perennial mystery lies the final source of the food we eat, the clothes we wear, the wood that builds our houses and starts our fires. Unfortunately, science does not yet know the exact chemistry or organism of leaf growth. Science believes that an assortment of some fifteen chemicals from the soil, with rain ‘ water and gases from the air, properly motorized by sunlight somehow produces the delicate magic of the leaf. Light, usually sunshine, is evidently the basic growth element for most plants. Few seeds will germinate unless the soil about them is exposed to light.
But the earlier theory that no other light but sunlight can cause seed to sprout or leaves to grow is now being dropped. Some of the best nurserymen are finding that two hours of intense electrical lighting each day will produce excellent blossoms from virtually any variety of garden flower; that in greenhouses or indoors if sunlight be supplemented by electric lights at night, or even during part of the night, many plants bloom or mature several weeks sooner than they will in the open, even though soil and temperature are the same.
Some of our best agronomists now believe that plant growth is actually affected by moonlight, even though this is a reflected light that has long been considered a “dead” or “negative” light. Dr. Randall R. Kincaid, scientific director of the Florida State Experiment has found that a small-sized seed, such as tobacco seed, will actually germinate when exposed only to bright moonlight. Physically speaking, we can only say that light is light, and we have no very good reason to argue that sunlight is basically different from other light in its effect upon living organisms.
However, there is good reason to believe that colors and length of light wave have a profound bearing upon plant growth or death. Flint, a famous experimental botanist, finds that in terms of plant growth, yellow, orange, and red are the colors of life, while the part of the spectrum which we see as blue and violet are colors of death or dormancy to the leaf. That is, the coarser light waves are best for plants, whereas the finer waves, including the ultraviolet, don’t help at all. This opens a tremendous field for thought and experiment.
Flint, assisted by Johnson of the Smithsonian Institution, also found a red that is poisonous to plants. This is a narrow band of coarse red just at the top edge of our visible color spectrum, and it is sure death to leaf and seed alike. Astronomers believe that the vast envelope of oxygen surrounding the sun, filters sunlight of this particular wave length. In their native state, plants are therefore not exposed to this coarse red. Develop a type of glass to accentuate or center this wave length, and unquestionably you have a tool of death to use against weeds or other plant pests. Or maybe a strong enough concentration of this coarse red could kill weed seeds already on or in the ground.
The same may be true of the plant poison contained in the blues and violets of our spectrum and in the ultraviolet rays. The Flint experiments prove that an oat sprout, growing heartily in ordinary un-filtered light, is definitely improved by yellow or golden rays, but when exposed to blue light, growth of the little plant ceases, its strength begins to fail, and presently it dies.
A famous French researcher, Le Clerc of the Paris Institute, goes further with this theory in analyzing the effect of Bordeaux mixture. Bordeaux mixture is a combination of copper sulphate and lime. For years it has been our greatest tool for fighting fungus diseases of plants. Fungi, tiny plants that suck the life out of larger plants, are one of the gravest menaces to plant life generally. We have been told that copper sulphate contained in the mixture poisons the fungus organism, and that the lime merely reduces the damage to the plant caused by the copper.
But Le Clerc proves that this cannot be poisonous to fungi because the copper is allied so tightly to the lime that it can never actually reach the parasite organism. He also proves that the leaf coating of the copper sulphate-and-lime compound called Bordeaux mixture allows only blue light to reach the fungus organism, since the lime niters out all the rest of the spectrum. Neither mildew spores nor fungi mycelium can grow under the poisonous blue ray. The fungus spores can germinate, but the blue light weakens them and they soon die.
All this opens an entirely new concept of plant-disease control, weed killing, speedy propagation of flowers and vegetables based upon the application and filtration of light, and upon light bands and death bands of the color spectrum.
Since sunlight is free, and of worldwide extent, since electrical facilities increase at an unprecedented rate, the possibility of man’s being able to control or influence plant life by means of light is of great importance and timeliness. We still don’t know exactly what light is. But we are learning a great deal more about what light can do.