Hero Tales of the Far North

by Jacob A. Riis

It has been said that Finsen was a sick man. A mysterious malady[15] with dropsical symptoms clutched him from the earliest days with ever tightening grip, and all his manhood’s life he was a great but silent sufferer. Perhaps it was that; perhaps it was the bleak North in which his young years had been set that turned him to the light as the source of life and healing. He said it himself: “It was because I needed it so much, I longed for it so.” Probably it was both. Add to them his unique power of turning the things of every day life to account in his scientific research, and one begins to understand at once his success and his speedy popularity. He dealt with the humble things of life, and got to the heart of things on that road. And the people comprehended; the wise men fell in behind him—sometimes a long way behind.

Dr. Niels Finsen

In the yard of Regentsen there grows a famous old linden tree. Standing at his window one day and watching its young leaf sprout, Finsen saw a cat sunning itself on the pavement. The shadow of the house was just behind it and presently crept up on pussy who got up, stretched herself, and moved into the sunlight. In a little while the shadow overtook her there, and pussy moved once more. Finsen watched the shadow rout her out again and again. It was clear that the cat liked the sunlight.

A few days later he stood upon a bridge and saw a little squad of insects sporting on the water. They drifted down happily with the stream till they came within the shadow of the bridge, when they at once began to work their way up a piece to get a fresh start for a sunlight sail. Finsen knew just how they felt. His own room looked north and was sunless; his work never prospered as it did when he sat with a friend whose room was on the south side, where the sun came in. It was warm and pleasant; but was that all? Was it only the warmth that made the birds break into song when the sun came out on a cloudy day, made the insects hum joyously and man himself walk with a more springy step? The housekeeper who “sunned” the bed-clothes and looked with suspicion on a dark room had something else in mind; the sun “disinfected” the bedding. Finsen wanted to know what it was in the sunlight that had this power, and how we could borrow it and turn it to use.

The men of science had long before analyzed the sunlight. They had broken it up into the rays of different color that together make the white light we see. Any boy can do it with a prism, and in the band or spectrum of red, yellow, green, blue, and violet that then appears, he has before him the cipher that holds the key to the secrets of the universe if we but knew how to read it aright; for the sunlight is the physical source of all life and of all power. The different colors represent rays with different wave-lengths; that is, they vibrate with different speed and do different work. The red vibrate only half as fast as the violet, at the other end of the spectrum, and, roughly speaking, they are the heat carriers. The blue and violet are cold by comparison. They are the force carriers. They have power to cause chemical changes, hence are known as the chemical or actinic rays. It is these the photographer shuts out of his dark room, where he intrenches himself behind a ruby-colored window. The chemical ray cannot pass that; if it did it would spoil his plate.

This much was known, and it had been suggested more than once that the “disinfecting” qualities of the sunlight might be due to the chemical rays killing germs. Finsen, experimenting with earthworms, earwigs, and butterflies, in a box covered with glass of the different colors of the spectrum, noted first that the bugs that naturally burrowed in darkness became uneasy in the blue light. As fast as they were able, they got out of it and crawled into the red, where they lay quiet and apparently content. When the glass covers were changed they wandered about until they found the red light again. The earwigs were the smartest. They developed an intelligent grasp of the situation, and soon learned to make straight for the red room. The butterflies, on the other hand, liked the red light only to sleep in. It was made clear by many such experiments that the chemical rays, and they only, had power to stimulate, to “stir life.” Finsen called it that himself. In the language of the children, he was getting “warm.”

That this power, like any other, had its perils, and that nature, if not man, was awake to them, he proved by some simple experiments with sunburn. He showed that the tan which boys so covet was the defence the skin puts forth against the blue ray. The inflammation of sunburn is succeeded by the brown pigmentation that henceforth stands guard like the photographer’s ruby window, protecting the deeper layers of the skin. The black skin of the negro was no longer a mystery. It is his protection against the fierce sunlight of the tropics and the injurious effect of its chemical ray.

Searching the libraries in Copenhagen for the records of earlier explorers in his field, and finding little enough there, Finsen came across the report of an American army surgeon on a smallpox epidemic in the South in the thirties of the last century. There were so many sick in the fort that, every available room being filled, they had to put some of the patients into the bomb-proof, to great inconvenience all-round, as it was entirely dark there. The doctor noted incidentally that, as if to make up for it, the underground patients got well sooner and escaped pitting. To him it was a curious incident, nothing more. Upon Dr. Finsen, sitting there with the seventy-five-year-old report from over the sea in his hand, it burst with a flood of light: the patients got well without scarring because they were in the dark. Red light or darkness, it was all the same. The point was that the chemical rays that could cause sunburn on men climbing glaciers, and had power to irritate the sick skin, were barred out. Within a month he jolted the medical world by announcing that smallpox patients treated under red light would recover readily and without disfigurement.

The learned scoffed. There were some of them who had read of the practice in the Middle Ages of smothering smallpox patients in red blankets, giving them red wine to drink and hanging the room with scarlet. Finsen had not heard of it, and was much interested. Evidently they had been groping toward the truth. How they came upon the idea is not the only mystery of that strange day, for they knew nothing of actinic rays or sunlight analyzed. But Finsen calmly invited the test, which was speedy in coming.