Apparatus Named After Our Academic Ancestors—VII

The demonstration apparatus in Fig. 1 is variously called Segner’s reaction turbine, Parent’s mill, the Scotch turbine, the Hydraulic tourniquet, or Barker’s mill. It was probably invented in 1760 by Andreas Segner using Hero’s steam reaction turbine as a model. This piece of demonstration apparatus is a fine example of the tinsmith’s art. It is 35 cm high, which makes it just the right size to fit into my kitchen sink and let me pour water into the funnel in the top. The central rotor spins freely about its axis. Projecting from the bottom of the rotor are two pipes, each closed at the end, but with a rearward-facing hole. Water spouts out of these holes, making the rotor spin. The 1857 catalog of James W. Queen & Co. of Philadelphia lists it at $7.50.

The device was invented by several people during the 18th century. In all cases, the principle of the reaction turbine is the same as the Hero’s engine that I will discuss later on. Robert Barker (d. 1745) was an English physician who also invented a reflecting microscope (remember that Isaac Newton developed the reflecting telescope in the latter years of the 17th century).

This was a practical device for powering mills. The Morris Canal was cut across the upper portion of New Jersey about 1850. The steep gradients meant that the canal boats had to be hauled up inclines—Scotch turbines were used as the motive power.

The thin-film interference demonstration device in Fig. 2 is attributable to C. V. Boys, better known for developing the method of making extremely thin quartz suspension fibers. The plastic wind shield is removed, and a thin film is formed across the open top of the hemisphere (whose interior is painted flat black) by dipping the apparatus into a soap solution. It is then placed on a rotator and spun. The film is viewed by reflected light, and a series of concentric, colored interference rings is observed. The film is thinnest at the center, and if the rotation rate is large enough, the center is black, indicating that the film is considerably thinner than the wavelength of visible light. This apparatus is listed at $14.50 in the 1950 Cenco catalog.

Charles Vernon Boys (1855–1944) is remembered as the author of the delightful book Soap Bubbles and the Forces Which Mould Them, first published in 1890. His quartz fibers were used in his 1887 radio micrometer, used for detecting infrared radiation.² The fibers were made by heating a small sample of quartz, and attaching one end of it to a straw arrow that he shot from a small crossbow. Strands of quartz, up to 90 ft in length, were 1 × 10⁻⁵ inches in diameter. Today we would use the diffraction pattern produced by putting the fiber in a laser beam to measure their diameter.³ 

The device in Fig. 3 is essentially a very long slide rule, with one scale on the numerous bars that are exposed on the outside frame, and the second scale on the outside of a rotating cylinder that slides in and out of the center of the frame. All settings can be made to the fourth digit, and some, close to 1.0000, yield five digits. The user was thus saved the drudgery of using logarithms to make precise calculations, although the cost of $80 in 1934 was very steep. It was made by the Keuffel & Esser Co. of New York, which specialized in slide rules, planimeters, and other calculating devices.

The device was invented by Edwin Thacher in 1881. He was a graduate of the Rennselaer Polytechnic Institute and was employed by the Keystone Bridge Company in Pittsburgh. He designed railway bridges and found that he needed more significant figures than he could obtain with a conventional slide rule. The calculating device that he developed was the equivalent of a slide rule 59 ft in length; I have never had the patience to verify this! Unlike contemporary slide rules, it has no trigonometric scales. I tried out my usual test for slide rules: calculating two times three, and it did give me six, but to many significant figures!

Arnold Sommerfeld published “Coupled Oscillations of a Helical Spring” in 1923.⁴ He had proposed the device (Fig. 4) in 1905, and the apparatus was made by the Central Scientific Company. In the paper, he extends the discussion of the Wilberforce pendulum (1894), in which the up-and-down oscillation of the spring alternates with a torsional oscillation. If the two oscillations have frequencies close to each other (the tuning is done with the small masses), the two modes of oscillation exchange energy for a long time. The tag on the apparatus shows that it was sold by Cenco in 1930; by 1936 it was out of the catalog, so it does not appear to have been commercially successful.

In the early years of the 20th century, Thomas A. Edison and his staff worked on the development of a useful storage battery for powering electric automobiles. The resulting nickel-iron battery (Fig. 5) with a sodium/lithium hydroxide electrolyte produced about 1.2 V, and was more efficient per unit weight than contemporary lead-acid storage batteries. After the demise of the electric car, the batteries were widely used in scientific work because they had a low internal resistance, and so gave a steady voltage output almost to the end of the charging cycle.

The original Ni-Cd battery was developed by the Swede Waldemar Jungner in 1899. Later he experimented with replacing the cadmium with iron. Edison took up the design and patented it in 1901. I have seen a picture of one of his electric automobiles. The front hood is up, and a half-dozen cells are arranged side by side in this space. I have hauled my own Edison cell about from place to place since 1986, and can assure you that they are heavy; this must have played havoc with the center of mass of the vehicle.

Hero’s engine (Fig. 6) is the generic name for a reaction device driven by steam. In this example, the upper vessel is filled with water heated by the small burner placed beneath it. Like every other Hero’s engine I have seen, this has no maker’s mark, but the style of the fittings marks it as dating from about 1900. We know nothing biographical about Hero of Alexandria. Even his dates are unknown, but internal evidence suggests that he was writing about 62 A.D. It is not clear whether he invented the two devices that bear his name: Hero’s fountain and Hero’s engine.

Hero’s fountain (Fig. 7) stands in the corner of the museum room, where I put it after doing some recent repairs. When I came to Kenyon in 1964, I was fascinated by this device; when you added water to the top pan, it flowed down to the bottom and created a pressure that ejected a spurt of water from the top. Soon I discovered that this jet was electrified; when I brought a charged hard rubber rod next to it, the jet moved to the side.

This piece of apparatus has led a hard life. During a building reconstruction in 1969, a two-by-four fell across it and shattered the bottom glass sphere. I gathered up the pieces and brought them home. Some years ago, I discovered that the Kenyon chemistry department had a broken Kipp’s apparatus; this has two glass spheres and is used to produce hydrogen. I salvaged one of them, ground off part of it with an abrasive disk, and cemented it into place. Sadly, the cement seeped into the mechanism, and it no longer works.

Karl Ferdinand Braun (1850–1918) shared the 1909 Nobel Prize with Guglielmo Marconi for his work on wireless telegraphy. To physicists, he is better known as the developer of the cathode ray tube (CRT) in 1897. His discovery of the rectifying nature of metal-to-semiconductor interfaces would seem to be one of the starting points of what we used to call solid-state physics. Early AM radio receivers, usually called crystal sets, used the contact between a thin wire (the “cat’s whisker”) and a galena crystal as the detector.⁵ 

In the example in Fig. 8, the cold cathode is at the right-hand side. In the middle is the accelerating electrode with a small circular hole in it for defining the electron beam, and at the left end, the curved end is coated with a phosphorescent material such as zinc sulfide. Those of us who remember oscilloscopes using CRT displays will recognize the two parallel plates that are used to deflect the beam. If an AC signal is applied to the plates, a streak will be visible on the screen. If you view this while moving your head rapidly to the side, you will see a sine wave drawn on the screen.

The induction coil, sometimes called the Ruhmkorff coil,⁶ was used in the 19th and early 20th centuries for exciting Geissler and other discharge tubes. The coil in Fig. 9, made by Edward S. Ritchie of Boston, is listed in the $150 to $200 range in his 1878 catalog, where he noted that he had devised “the mode of winding the secondary helix in strata, in planes perpendicular to the axis, requiring but slight insulation, and rendering the increase in the tension [voltage], and length of the spark to two or three feet, practicable.” The mechanism on the base is the remains of the interrupter used to produce the intermittent current to excite the primary coil. The coil in the picture has a patent date of April 1868.

Ritchie was one of the prominent makers and sellers of apparatus for natural philosophy in the second half of the 19th century. I have used his catalogs, since I first photocopied them at the Smithsonian Institution in 1975, to identify a good many pieces of apparatus and see how they are used. Recently I tuned to the television program How It’s Made and discovered a segment on the construction of very fine naval compasses being made in Ritchie’s plant in the Boston area, 170 years after Ritchie started to make physics apparatus!

The basic galvanometer in Fig. 10, devised in 1825 by the British physicist William Sturgeon (1783–1850), allows all of the various combinations of current and magnetic needle directions to be tried out. By making suitable connections to the terminals, current can pass to the right or to the left, both above and below the needle. Current can be made to travel in a loop to double the effect, and, with the aid of two identical external galvanic circuits, the currents in the two wires can be made parallel and in the same direction. Note that the wires are insulated from each other where they cross.

Sturgeon is perhaps best known for his development of the electromagnet. However, like many other electrical experimenters, he worked on developing the galvanometer based on Oersted’s 1820 discovery that a current-carrying wire will have a force exerted on it by a nearby permanent magnet.

The electromagnetic wave (light, microwave, radio waves) can be described with two vectors, starting with the E vector, representing the electric field comprising the wave. At right angles to this is the H vector, which describes the magnetic field component of the wave. Next there needs to be a vector to tell us the direction of propagation of the wave. This is the Poynting vector, produced by the cross product of E and H: P = E × H. The magnitude of the vector is also a measure of the energy density of the wave.

Who was John Henry Poynting (1852–1914)? Between 1903 and 1911, he published 15 papers on the pressure of light. James Clerk Maxwell published his key article on the electromagnetic theory of light in 1873, and for the rest of the century, a number of physicists worked at putting it in its present form; this group included Poynting as well as Lodge, Heaviside (the “Heaviside layer”), Fitzgerald, and Hertz. A study of this work would make an interesting article for this journal.

In my personal collection of early physics books, I have three volumes that Poynting wrote jointly with J. J. Thomson (the “electron man”). They are A Textbook of Physics: Properties of Matter, followed by textbooks with the same running title, published in the latter years of the 19th century, and republished many times after that.⁷ 

As I was writing this article, I was delighted to read Steven Morris’s article on the Poynting vector in the September 2022 issue of The Physics Teacher.⁸ This brought me back to an incident that took place in a course in electromagnetic waves that I took in the second semester of my junior year at Amherst College. There were 17 of us in the class, and the idea of the vector struck many of us as funny. Soon pieces of paper with “pictures” of the vector started to appear taped to the walls of the classroom!

Since 2002, I have been writing page fillers for the American Journal of Physics. These run to about a half page and consist of a picture that I have taken of an early piece of physics teaching apparatus and a 100-word caption. To date, something over 850 of these have been published, with 1000 already written. When writing the present paper, I looked for physicists whose names are associated with apparatus.

Thomas B. Greenslade Jr. is professor emeritus in the physics department at Kenyon and a frequent author for The Physics Teacher.