Home / Patents & Innovations / Private Label Trade Names on American Pocket Watches: The Non-Magnetic Watch Company: Part 15: Alternative Anti-Magnetism Devices: Anti-Magnetic Ajax Insulator

Private Label Trade Names on American Pocket Watches: The Non-Magnetic Watch Company: Part 15: Alternative Anti-Magnetism Devices: Anti-Magnetic Ajax Insulator

“Ajax Insulators” Advertisement, The Jewelers’ Circular, August 3, 1898.
Pictured: “Ajax Insulators” Advertisement, The Jewelers’ Circular, August 3, 1898.

As electricity was being adopted across the globe in the 1880s, the watch industry was met with the challenge of magnetism from electromagnetic fields. 

When the delicate hairspring, balance, and steel parts of the watch movement were magnetized, the watch would operate erratically. This result was immensely problematic on railroads, where precise timekeeping was critical.

While Charles-Auguste Paillard was developing palladium alloys for watches that were non-magnetic, other companies scrambled to create devices to protect watches from the influences of magnetism. 

In July 1888, Atkinson Bros. introduced the Ajax Watch Insulator as a protective device shielding the entire watch from the influences of magnetism. The insulator was manufactured from highly magnetic sheet iron and lined with plush material, designed to fit snugly around any watch case to absorb and redirect magnetic fields. 

In July 1889, the Metropolitan Watch Company was organized by Henry F. Atkinson to manufacture and distribute the Ajax Insulator at a greater scale. Atkinson was associated with several companies in the watch industry, including the Lancaster Watch Company, the Keystone Watch Club Company, and the Essex Watch Case Company. Within a year, a trademark and patent had been secured for the anti-magnetic device. The company began to offer a free Ajax Insulator with every purchase of a Keystone Dust-Proof Watch to incentivize sales.


Ajax Insulator Ad with Keystone Dust Proof Watch by the Atkinson Bros., The Jewelers’ Circular and Horological Review, May 1889

The following year, as the entanglement of the companies owned by Atkinson Bros. finally collapsed under the stress of the Keystone Watch Club Company scandal, the Metropolitan Watch Company fell into bankruptcy. 


Early Advertisement for the Ajax Insulator, The Jewelers’ Circular, September 14, 1892

During this transition, rights to the Ajax Insulator were assigned to the Newark Watch Case Company. As other companies began to produce similar shielding insulators, the Newark Watch Case Company quickly published a notice in The Jewelers’ Circular warning of patent infringement:

“The Watch Protectors and Insulators manufactured by us are made under protection of Letters Patent No. 413,644, and dated October 29th, 1889.

As certain inferior Protectors and Insulators are now being offered to the public which are infringements of our said Letters Patent, we deem it necessary to notify the trade and public that we have begun suits against the manufacturers and dealers of the same in the U.S. Circuit Courts in Trenton and Philadelphia, and we are vigorously prosecuting the same.”Patent Infringement Notice, The Jewelers’ Circular, July 29, 1891


Patent Infringement Notice, The Jewelers’ Circular, July 29, 1891

The Ajax Insulators continued to be sold by the Newark Watch Case Company until after 1900, though the popularity peaked in the 1890s. Many of the insulators have been lost or discarded over the years, creating a difficult challenge for avid collectors.

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