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

The average university professor is happy if he can take a full year’s sabbatical once in every seven years. But nothing is ever “average” with Wood. He took his first sabbatical in 1910- 11, another in 1913-14, went overseas again in a major’s uniform in 1917, then again soon after the armistice, and has been making long visits to Europe in intervals ever since. His growing international fame, his many invitations to lecture before learned societies abroad, his researches with European colleagues, the funds derived from the Adams endowment for publication of his work by Columbia University, the appreciation of Johns Hopkins, which always gave him half pay during absence, all contributed toward making these triennials not only possible, but reasonable.

Wood began his first so-called sabbatical in the summer of 1910, after devising earlier in the year a new type of diffraction grating which he named the Echelette.[9]

He went first to London, where he delivered the Traill Taylor Memorial Lecture, an annual function of the Royal Photographic Society, and the initial “Thomas Young Oration”, a similar affair just started by the Optical Society. He then joined his family in Paris. Elizabeth, now aged twelve, was placed in school there, and Robert, Junior, aged sixteen, at school in Geneva. Margaret, now a tall young lady of seventeen, accompanied her parents to Berlin.

In Berlin, the Woods found a pension facing the Tiergarten, near the school where Margaret chose to study art. Wood’s amateur talents in this direction had been increased in their transference to the daughter, who later made a name for herself as an outstanding portrait painter.

The family was now joined by their old friends, the Trowbridges. With Trowbridge, Wood attended the celebration of the hundredth anniversary of the founding of the University of Berlin. They went as official delegates from Johns Hopkins and Princeton. The ceremonies were elaborate. Kaiser Wilhelm was there in gorgeous uniform. With him was the pretty crown princess with whom, according to Trowbridge, the irrepressible Wood (delegate from Johns Hopkins!) carried on a mild flirtation during the tedious ceremony.

Soon Wood was deep in research with Professor Rubens, who fifteen years before had encouraged him to change from chemistry to physics. The research with Rubens was on a new method they had developed for isolating and measuring the longest heat waves ever discovered. It was at the time when efforts were being made all over the world to fill the gap in the spectral region between the longest infrared heat waves and the shortest electric or radio waves, for Maxwell’s theory showed that light and electromagnetic waves differed only in length. The method which they discovered was called focal isolation and depended on the odd circumstance that crystalline quartz was exceedingly transparent to a group of waves far longer than any discovered in the infrared, while having at the same time an index of refraction much higher than for visible light, in other words “anomalous dispersion”. They succeeded in isolating heat waves of over 0.1 of a millimeter[10], the longest observed at that time.

Wood announced one day at lunch at the pension in which they were living, “We’ve found and measured the longest heat waves ever observed”.

“How long were they?” asked his daughter Margaret.

“One tenth of a millimeter”, announced Wood triumphantly.

“I don’t call that very long”, commented Margaret in a bored tone.

These invisible rays from the lamp had very curious properties, they found. A quartz plate so heavily smoked that the sun was invisible through it was perfectly transparent to them; and the same was true for a plate covered with a thick opaque layer of finely divided metallic copper, while a plate of hard rubber half a millimeter thick transmitted about 40 per cent.

Plates of rock salt, which are extremely transparent to the greater part of the infrared spectrum previously studied, were absolutely opaque to these rays.

It was a matter of considerable theoretical interest to find out whether an extremely thin plate of salt would transmit anything.

“We need a plate half a millimeter thick, if possible”, said Rubens. “I shall order one from Steinheil [an optician and lens-maker]. He can do it, I think, and we shall have it in two weeks”.

“Why not make it ourselves?” said Wood.

“Can you, then, grind and polish a rock-salt plate?” inquired Rubens in surprise.

“I don’t know”, said Wood. “I think so”.