Doctor Wood. Modern Wizard of the Laboratory: The Story of an American Small Boy Who Became the Most Daring and Original Experimental Physicist of Our Day-but Never Grew Up

He found a way of intensifying the light contrasts in paintings by photographing the original painting, preparing a lantern slide from the negative, and projecting it with a lantern placed at such a distance as to secure exact registration of the image on the original. In this way, a powerful illumination was thrown on the high lights and a feeble light on the shadows, with all the intermediate gradations correctly controlled. The effect in a dark room is quite startling — a landscape fairly glows with sunlight. After viewing it for a few minutes, if the lights in the room are turned up and the lantern turned off, the picture looks as if it had not been dusted for years. The audience was amused when a large portrait of a prominent trustee was illuminated in this way, and Wood found that by joggling the projecting lantern the pupils of the portrait’s eyes glanced rapidly back and forth from right to left in a most lifelike manner.

Wood saw a possible practical use of this discovery in connection with stage effects, in which the painted backdrop could be illuminated by a lantern in the gallery which projected upon it a photograph made in a similar manner. This, he thought, should be particularly effective in sets which were supposed to be drenched in sunlight.

Wood’s most important work, however, continued to center around the optical investigation of sodium vapor. Examining the absorption spectrum of sodium vapor in the ultraviolet, he succeeded in increasing the number of lines of the principal spectral series from the eight previously known to fifty. It was, and still is, the longest spectral series known. This discovery was later cited by Niels Bohr as a beautiful proof of his new theory of atomic radiation, for which he received the Nobel prize. Another experiment of Wood’s at the same time that was also important in the new theories of radiation was his demonstration that the fluorescent light emitted by sodium vapor (and potassium and iodine vapor as well) was polarized — that is, a large percentage of the light vibrated in a single plane. At the same time, Wood was working with one of his students, H. W. Springsteen, on magnetic effects on polarized light. Corbino, an Italian physicist, some years previously had noted that by placing a sodium flame between the poles of an electric magnet and passing a beam of polarized white light through it, the plane of polarization of some of the yellow light was rotated several degrees. Wood and Springsteen, working with metallic sodium heated in a glass tube instead of a sodium flame, obtained rotations as great as 14° in the yellow region, and discovered marked traces of rotation in other regions of the spectrum. Wood was to continue this work for a number of years, with more powerful magnets and improved technique, obtaining rotations as great as 1,440° or four complete revolutions, results of great value to the theoretical physicists.

In the summer of 1909 Mars was in opposition, and all the astronomers were on tiptoe. Wood took out the six-inch lens of his big spectroscope at East Hampton and mounted it on a block of cement on the lawn in front of his laboratory door. A silvered mirror reflected the light of the red planet through the lens and thence to an eyepiece forty feet away, at the back of the dark laboratory, where he viewed the magnified image of the planet while lying comfortably on the floor on an old mattress.

During this same summer he resumed his experiments on photographing the moon in ultraviolet light, and showed the possibility of getting some notion of the nature of the rocky surface of the moon by photography with light confined to selected regions of the spectrum. His first paper on the subject was communicated to the Royal Astronomical Society of Great Britain by Sir Robert Ball, the Astronomer Royal, and published in the Monthly Notices of the Society, from which I quote:

The preliminary experiments were made at my summer laboratory at East Hampton, Long Island, N. Y., with an improvised instrument made out of odds and ends. A thin film of silver, opaque to all visible light, transmits quite freely ultra-violet light of wavelength 3000, but these rays will not go through glass, consequently a lens made of quartz was necessary. A photographic telescope was made of a three-inch silvered quartz lens of six-foot focus mounted over one end of a piece of galvanized iron stove-pipe, with a plate- holder at the opposite end. This was lashed to a five-foot astronomical telescope which served for following the moon, during the three-minute exposure which was necessary. Both were attached to an equatorial mounting made of an old bicycle frame embedded in a block of cement, the steering axis pointing to the pole star. A slow motion enabled me to make exposures of several minutes if necessary. A more detailed description of this instrument will be found in the English Mechanic for November 12, 1909.