White’s Patent Model of a Hot-Air Furnace - ca 1872

This model was filed with the application to the U.S. Patent Office for Patent Number 134,118 issued to Cyrus White of West Roxbury, Massachusetts on December 17, 1872. Mr. White’s patent was for improvements in the fresh air intake, ductwork, heat exchanger, and flue that would be used in conjunction with an overall furnace apparatus which was not a part of the patent. These components are shown in the accompanying image as upper and lower rectangular chambers interconnected by pipes. The drawings submitted as part of the patent application illustrate how a combustion chamber and a surrounding masonry structure would complete the overall heating installation. The drawings can be found in the patent document online (www.USPTO.gov/patents/process/search/index.jsp). Fresh entered the lower chamber via an opening on the right side. The cut out area at the left was the access for the combustion chamber which would have been located at the semi-circular metal collar shown above the air chamber. The upper chamber was the heat exchanger, the design of which White claimed as new in his patent. The exhaust gases from the combustion chamber entered via a hole located directly above the semi-circular collar previously mentioned. The exhaust was carried to a chimney through a hole at the right end of the heat exchanger. The hole seen at the left allowed access to the inside for cleaning and would have been closed by a door during operation. The vertical tubes seen in the image carried cold air upwards and through the outer casing of the heat exchanger where the air was heated. The heated air exited where these tubes reemerged from the heat exchanger on the top. White provided for additional heating to take place via smaller pipes that drew cold air from just outside of the heat exchanger. The inlets for these pipes can be seen just above where the larger pipes enter the heat exchanger. The smaller pipes communicated to a small chamber inside the outer heat exchanger case. Air heated in this chamber also exited at the top. White’s patent simply stated that the hot air exiting from the top could be conducted as desired to any apartments of the building. The other features claimed as new in the patent dealt with a set of “jet-holes” which were to be placed in a collar where the combustion chamber exhaust met the heat exchanger. The S-shaped tube seen between the cold air chamber and the heat exchanger provided fresh air to the jets. White claimed the resulting jets of air into the hot exhaust gases caused more complete combustion and better heating. White’s patent design led to the Cyrus White & Company, located in Jamaica Plain, MA. In 1888 it was noted that the company had been successful selling and installing White’s “Tropic” Furnaces.
The patent model is constructed of unpainted tin plate and represents the key elements of the patent as shown in the image and described above.
Currently not on view
Object Name
patent model, furnace, hot air
date made
ca 1872
patent date
White, Cyrus
overall: 9 1/8 in x 5 1/4 in x 10 1/2 in; 23.1775 cm x 13.335 cm x 26.67 cm
associated place
United States: Massachusetts, Boston, West Roxbury
ID Number
accession number
catalog number
patent number
Engineering, Building, and Architecture
Patent Models
Patent Models
See more items in
Work and Industry: Mechanical and Civil Engineering
Patent Models
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Transfer from Department of the Interior

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