It’s an appealing scientific curiosity: no batteries, no winding key, and enough movement to make you stop and investigate. For a glass salesman, that last quality was particularly useful.
We come to you today with a radiometer unlike any other. This piece would have been the #1 tool in the salesman's arsenal.
Blue Ridge Glass used radiometer demonstrations to help explain how architectural glass could control incoming radiant heat. A product’s performance could become something a prospective customer could watch. The salesman brought the science along in a carrying case.
Today, these demonstrations connect several collecting interests: scientific instruments, architectural materials, industrial history, and salesman samples. Their value depends partly on how much of the original demonstration survives and whether its individual components still belong together. When you consider a salesman sample's value, you must think of how the piece would have been used. If it still captivates an audience today, it's likely to be quite valuable.
Have a salesman sample you're ready to sell? Email us now at info@industrialartifacts.net! We're ALWAYS buying!
WHY DO THE LITTLE VANES SPIN?
The University of Wisconsin–Madison’s physics museum dates William Crookes’s invention of this type of radiometer to 1873, during his research into thallium. Inside the bulb, a lightweight rotor carries vanes with dark surfaces on one side and reflective or light-colored surfaces on the other.
Much of the air has been removed, leaving a partial vacuum. That remaining gas is essential to the instrument’s behavior.
When illuminated, the dark surfaces absorb more energy and become warmer. The temperature difference affects how the remaining gas interacts with the vanes, particularly around their edges. Those forces produce rotation. Simon Fraser University’s explanation describes both gas collisions and thermal creep, or the movement of gas along surfaces from cooler toward warmer regions, as contributors.
The result looks wonderfully simple. Explaining it kept physicists considerably busier.
By taking advantage of this simple concept, Blue Ridge could easily demonstrate to clients the value of having treated glass on their commercial buildings.
BLUE RIDGE’S BUSINESS WAS WINDOWS WITH OPTIONS
According to Kingsport Public Library and Archives, Blue Ridge Glass Corporation was organized in Kingsport, Tennessee, in 1925. From there, Blue Ridge embedded itself into industrial glass manufacturing and helped open the door for a wider variety of new glass to hit the market. A window pane could be selected for more than its dimensions: Color, surface pattern, frosting, thickness, and embedded wire offered different combinations of appearance and performance.
The Corning Museum of Glass’s collection of Blue Ridge samples illustrates that variety. It includes several Aklo Fine-Tex examples, with frosted and wired variations. Those small panels preserve the choices that manufacturers offered and the technical work required to produce them.
The company’s business also became part of a larger international operation. A merger announcement published in July 1958 reported the combination of American Window Glass Company and Blue Ridge Glass Corporation to form American-Saint Gobain Corporation. Blue Ridge’s operations would continue as a division of the new company.
Before any of those corporate names reached a building specification, somebody still had to explain why a particular pane was worth choosing.
A DEMONSTRATION YOU COULD CARRY
The Blue Ridge Glass demonstration kit featured below is dated to around the 1930s. From the moment the salesman opened the case, you could tell that this demonstration would be more involved than your typical ad piece.
Its fitted case combines an electric light source, curved reflector, radiometer mount, instruction material, and separate storage for glass samples. Labels identify varieties including Frosted Aklo and Bluewhite, alongside other patterned, textured, and dark panels.
The arrangement allowed selected samples to be placed between the source and the radiometer. Other differences, including color, texture, and opacity, were available for direct visual comparison.
THE ADVERTISEMENT EXPLAINS THE SALES PITCH
A later advertisement provides unusually clear evidence of how this method was promoted.
In the March 1951 issue of Architectural Record, an advertisement for Frosted Aklo Glass promises that it “brings in sunLIGHT,” “shuts out sunHEAT,” and “reduces GLARE.”
The advertisement connects those claims to working conditions inside industrial buildings. With skyscrapers on the rise (literally), more and more people were growing concerned of the obvious detriment that untreated glass would bring to the work day. A kit like this quickly gathered everyones concerns into one room, and promptly gave them a solution: Blue Ridge Alko Glass.
The demonstration’s persuasive appeal is easy to understand. A page of specifications asks the customer to interpret numbers. A moving instrument supplies an immediate point of interest. Ideally, the salesman had both.
The vanes were doing their share of the talking.
WORKING CONDITION AND ORIGINALITY ARE DIFFERENT QUESTIONS
For collectors, this kit offers a useful lesson about scientific equipment: operation and originality need separate consideration.
Do the glass samples carry relevant maker and product labels? Does the instruction material correspond to the equipment?
A replacement can help explain an operating principle while changing the historical composition of a set. Likewise, an original but damaged component can retain important evidence of how the apparatus was supplied. Each deserves an accurate description. Age, maker identification, condition, surviving components, and documented history all contribute to an assessment.
If you’re considering selling a scientific demonstration kit, or any salesman sample, contact us right away! You can reach us by email at info@industrialartifacts.net and by phone at 815-299-7625.
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