James Loudon and Rudolph Koenig: Protagonists of the Brass and Glass Era

The first U of T physics laboratory was founded at University College in 1878. The two most responsible for equipping the lab, a Canadian professor and a Parisian instrument maker, formed a lasting friendship.

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To found a physics lab, you need instruments. In the 19th century, the best instruments came from Europe. In June of 1878, Professor James Loudon (1841-1916) travelled to London and Paris with $12,000 to equip a physics laboratory.

In Paris, he visited the workshop of the German-born acoustical instrument maker Rudolph Koenig (1832–1901). This visit established a friendly twenty-year relationship during which Loudon purchased a collection of Koenig’s instruments. In return, Koenig gathered European instruments to meet the University’s requests.

Acoustics and sound perception were major research fields in the 19th century. Koenig was an influential researcher whose work explored, and sometimes critiqued, the ideas of the famous German experimentalist Hermann von Helmholtz (1821-1894).

Instruments of this “brass and glass” era were handmade and often meant for demonstration. They represented an institution’s status and ambition. Their evident quality has made them much more likely to be kept than more recent scientific artifacts.

Portraits of James Loudon (left) and Rudolph Koenig (right). The Loudon portrait is from a black-and-white photograph of a painting by the Irish portraitist Sir William Orpen, likely done in the first decade of the 20th century, digitized by UTARMS as A1973-0026/241P (86)/ 2000-20-7MS. On the right is an engraving of Koenig, likely made for print publication before 1890. Public domain via Wikimedia.

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This instrument, designed between about 1865 and 1872, is one of Rodolph Koenig’s major technological contributions to acoustical research. Called a “Manometric Flame Analyser for the Timbre of Sounds”, it visualizes the component frequencies of a complex sound much as a spectroscope reveals the individual wavelengths of a light source.

The basis is a technology promoted by Hermann von Helmholtz: a tuned resonator that responds to a narrow frequency range. This instrument incorporates 14 resonators ranging from 96 to 1,280 Hertz. Koenig’s innovation is the “manometric flame”, a capsule with one compartment linked to a single resonator and the other to a gas flame. Separating them is a membrane that transmits the vibration of the acoustical source to the flow of gas. When a resonator resonates, its corresponding flame flickers.

With an array of resonators and flames, the constituent frequencies of complex sounds are visualized. This effect is enhanced by the mirror apparatus. whose rotation makes a flickering flame appear as an undulating line. This instrument is very challenging to operate.

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This is a D’Arsonval-Deprez-type galvanometer, an instrument for measuring electrical current based on the deflection of an electrical coil within the field of a permanent magnet. Over much of the 19th and 20th centuries, galvanometers were extremely common across many fields.

The model seen here is a ballistic galvanometer, designed to measure the quantity of charge over an interval using the moment of inertia of a broad coil; this instrument’s coil produces an oscillation lasting around eight seconds. When it was made, such tools would have been among the few means to measure transient or fluctuating currents.

This instrument was made by the Carpentier atelier in Paris. Its acquisition is recorded in letters, sent in October of 1895, between Rudolph Koenig to James Loudon.

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J. S. Plaskett: Technical Skill and the Early Laboratory

John Stanley Plaskett (1865–1941) was the first of many technicians who supported the achievements of the physics laboratory. He went on to become a major Canadian astronomer.

James Loudon hired John S. Plaskett in 1890 to maintain and operate the electrical instruments of the physics laboratory. Plaskett, a Canadian, had worked in the manufacture of dynamos in Thomas Edison’s Schenectady factory. Plaskett remained at the University of Toronto until 1899.

The two instruments below show his handiwork in the early lab. The first, a Carpentier ammeter bears the inscription. “Recalibrated May 25th 1893 by J.S.P….”. The second, a resistance box, is stamped with his initials.

Plaskett’s time at the University of Toronto launched him on a stellar career. He went on to oversee the design and construction of the 72-inch reflecting telescope at the Victoria Dominion Astronomical Observatory. Completed in 1918, it was then the second-largest telescope in the world. In 1922, he identified the binary nature of HR 2422 , now known as “Plaskett’s Star”.