A Cooking Revolution: Mary Jones De Leon

In honor of Black History Month, IPWatchdog will be featuring profiles of black women inventors—some of whom are little-known and many of whom never profited from their inventions—throughout the month of February.

In 1873, Mary Jones De Leon was granted U.S. patent No. 140,253 for her invention titled ”Cooking Apparatus.” De Leon, who resided in Baltimore, Maryland, is believed to be the second black woman to receive a U.S. patent, following Martha Jones in 1868. De Leon’s invention was an apparatus for heating or cooking food by dry heat and steam the same time. Her cooking apparatus was an early precursor to the steam tables now used in food buffets to keep food warm during gatherings.

Advances in the Art of Cooking

De Leon’s cooking apparatus included a lamp for providing dry heat, as well as a water reservoir for providing steam, which “reliev[ed] the dryness of the heat, and prevent[ed] the articles of food on the plates … from becoming scorched or otherwise injured.” The invention would prove to be useful when feeding large families or at gatherings, where individuals are served at different times. At a time when meal preparation was a large part of a homemaker’s work and was very time consuming, advances in technology related to storing, preserving, preparing and serving food could be life changing. De Leon’s apparatus combined the function of a cooking oven and a steamer into one apparatus, thereby saving time and space.

The cooking apparatus included a vessel with a ledge for an annular water-reservoir. The reservoir was perforated to allow steam to escape to the interior of the vessel when the water in the reservoir became heated by a heat lamp. A plate having a series of holes was also positioned within the vessel for receiving food to be heated or warmed. Heat from the kerosine lamp was directed to the underside of the plate by a series of tubes for heating the food, in addition to heating the water in the reservoir to generate steam. Other patents directed to cooking via heat lamps were issued, such as U.S. Patent No. 126,874 to John Graham Cooey, but De Leon’s cooking apparatus stood out due to its simplicity and multi-use functionality.

From the Patent:

“The nature of my invention consists in the construction and arrangement of an apparatus for heating food by dry heat and steam at one time, and which apparatus may also be used for cooking, as will be hereinafter more fully set forth. … At the same time as the dry heat from the lamp is used, the steam arising from the Water in the reservoir relieves the dryness of the heat and prevents the articles of food on the plates E from becoming scorched or otherwise injured. By placing the lamp B on its seat in the reservoir, and substituting a solid plate for the plate D, this apparatus may also be used for cooking, if so desired. The whole apparatus is covered by a lid.

Having thus fully described my invention, what I claim as new, and desire to secure by Letters Patent, is

    1. In an apparatus for heating and cooking food, the combination of a lamp and the annular water-reservoir, having a perforated cover, with the plate or plates containing the articles to be heated, whereby said articles are subjected to the combined action of steam and dry heat, while the latter may be used for cooking purposes, by placing the lamp in its seat on the water-reservoir, substantially in the manner herein set forth.”


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2 comments so far.

  • [Avatar for David Lewis]
    David Lewis
    February 8, 2021 04:59 pm

    Regarding the above comment, it is also a natural law that when hear food it cooks, and when you provide steam it remains moist :).

    On a serious note, thank you for bringing to our attention these forgotten people, whom history should have paid more attention to.

  • [Avatar for Pro Say]
    Pro Say
    February 8, 2021 04:00 pm

    Sadly, were Mary to attempt to protect her well-deserving invention against infringers here in America, the CAFC would rule it ineligible for patenting.

    Why? Because cooking is abstract . . . having been performed by cave men and women since long before recorded history.

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