The Wood family spent the summer at Cataumet, Massachusetts, on Buzzards Bay. Wood’s cousin, Bradley Davis, was working at the Marine Biological Laboratory at Woods Hole, within bicycling distance, and some old friends owned a summer cottage there. Wood says he was taken on as outboard ballast by the owners of one of the small racing boats that took part in all the Corinthian yacht club races; he hugely enjoyed the jockeying for a start, which was a new experience for him, though he had sailed a small boat all his life. While in bathing one day he happened to invert a wooden pail over his head, and holding it down on his shoulders with his hands and kicking with his feet, amused the children by the sight of an animated pail moving along by itself. Next day he cut a rectangular hole in one side, set a piece of plate glass in it for a window, and put forty pounds of lead boat ballast around the rim. This weight held the bucket down over the head when filled with air and submerged in water, and enabled the wearer to sink comfortably to the bottom. Then, antedating Beebe, they connected the bucket to a bicycle pump (operated on a rowboat) with twenty feet of rubber tubing, and stayed under water as long as they liked, viewing the fish, seaweed, and submarine landscape.
STUDENT IN BERLIN: Wood in the private laboratory he rigged up in the attic of the University of Berlin laboratory.
LILIENTHAL’S LAST FLIGHT: A photograph made by Wood in 1896 of the last successful flight of Otto Lilienthal, Germany’s great pioneer glider. On his next attempt the following day – Wood was invited to attend but couldn’t – Lilienthal was killed.
Chapter Six.
Wood as Campus Wizard, Thawer of Pipes, Driver of Steam Wagons, Roman Senator
When Robert Wood obtained in 1897 the academically humble and poorly paid post of junior instructor in physics at the University of Wisconsin, in Madison, he was a young man just turning his twenty-ninth year, married, with two children — a third, Elizabeth, soon to be born — and he was completely ignorant of the highly special branch of physics destined to bring him his later greatest glory. But while he knew next to nothing yet of physical optics, he was already a daring experimenter in the general field, and began almost immediately to revolutionize undergraduate classroom technique at Madison.
It all began gaily with a series of lecture circuses, staged for the edification and joy of the students, climaxing soon in mirages and tornadoes. The idea that he, as well as Nature’s God, could create these phenomena had come to him the previous summer in San Francisco, when he’d noticed one day a beautiful mirage on the city sidewalk at the top of a hill, where one could look along a long stretch of sun-heated pavement with a sky background behind it. The pavement appeared to be flooded with water in which the inverted reflection of pedestrians was clearly visible. Wood had stationed his two small children at the end of the pavement and photographed the result. Today this type of mirage is observed constantly by motorists on pavements or streets, but at that time it had only been reported as occurring on wide expanses of hot sand in the desert. To create his miniature phantasmic oases and actual whirling sandstorms he procured four flat sheets of iron, each about four feet long and eight inches wide. These he laid end to end, supported on iron stands, making a long, narrow, level vista, which he sprinkled thickly with sand. At the further end he mounted a mirror which, when viewed from the opposite end, showed the reflected image of the sky- backed window. A row of miniature mountains and some palm trees, cut out of paper and arranged on the sand in front of the mirror, represented the horizon of his desert landscape, which was warmed from below by a row of small gas burners under the iron plates instead of from above by the sun. Would it work on this small scale? He lit the burners and commenced observations. The mountains and palm trees were clearly silhouetted against the bright sky, but presently a small pool of brilliantly shining water appeared in front of them at the base of the mountains. If the eyes were raised an inch or two above the level of the sand, the lake vanished, only to reappear as soon as the viewpoint was depressed, just as does a real mirage if we ascend a small hillock. And now the pool increased in size and the reflected images of the mountains appeared, and “if the eye was lowered a trifle more, the mountain chain disappeared completely in the illusory lake, which had now become an inundation”. Needless to state, the students were enchanted — almost to the point of howling with joy — and from then on the new “prof” was ace-high.
Wood next regaled them with his tornadoes. The atmospheric conditions (a layer of hot air close to the ground, with cooler air above) which exist with mirages also give rise to the “dust whirls” so often seen on American deserts and, on a larger scale, to tornadoes. One of the metal plates (cleared of sand) was sprinkled with precipitated silica powder and heated by a few burners. In a few minutes beautiful little whirlwinds began to run about over the surface, spinning the light powder up in funnel-shaped vortices, which lasted sometimes ten or fifteen seconds. By sprinkling a large square plate of sheet iron with sal ammoniac and heating it strongly by Bunsen burners, white fumes were given off, and presently, at the center of the plate, there mounted to a height of six or eight feet a most perfect miniature tornado of white smoke!
A little later in the year he invented a new form of pseudoscope. When viewed through this instrument, an old-fashioned washbowl appeared as a white dome, and when a marble was dropped into it, it seemed to roll up and down over the surface of the dome in defiance of the law of gravitation, finally stopping on the summit!
Another memorable lecture-room stunt was his demonstration of the curved flight of baseballs as pitched by the then Dizzy Deans — leading on to the parabolic orbits of planets and comets as pitched by the Lord God Almighty. The limited space in the lecture room had raised difficulties. If the curve was to be made at all apparent in that limited space, the ball would have to be exceedingly light and the axial rotation very rapid. Wood found the ordinary oak ball or oak apple suitable for this purpose. A ping-pong ball might have been even better. A strip of rubber band six or eight inches long and one- eighth inch wide was wound under tension around the ball, two or three turns being enough, and the ball catapulted forward by means of the remainder of the band. A total deflection of forty-five degrees was easily obtained, and when pitching the “rise” (in which case the free part of the band is below) the ball, starting in horizontal flight, would often ascend half way to the ceiling. Try it for yourself, if you don’t believe it.
An experiment followed showing in miniature the elliptical and parabolic orbits of the planets and comets around the sun. The conical pole piece of a vertical electro-magnet was covered with a large sheet of plate glass, and a steel bicycle ball projected toward a point a little to one side of the magnet, which represented the sun. The ball whirled around in a beautiful ellipse with the sun at one focus, as Wood demonstrated with a glass plate covered with a thin film of soot, obtained by holding it over a smoking flame. In this case the ball left a record of its path on the film.
The publication of a scientific paper on this experiment led Wood into his first brief polemic. An older professor of physics in one of London’s universities criticized the paper in a letter to the London Nature, saying that the experiment did not illustrate Newtonian orbits, as the magnetic attraction varied as the inverse fifth power and not as the inverse square as in the case of gravitation. This was young Wood’s first slap — but he sat down and drew a diagram of his experiment with the lines of magnetic force put down and realized at once that the ball was not coming in along the lines of force, but was cutting across them at an angle, and that it was the horizontal component only that governed the orbit. He set one of his young students to measure the effective force in the plane of the glass plate, and it turned out to be very nearly proportional to the inverse square. In the meantime, letters of criticism had appeared in several other English technical journals, and Wood joyfully sent off a rejoinder giving the results of the actual measurements.