page_title: Neilson v Harford
section_title: Judgment
hierarchical_section_title: Neilson v Harford / Judgment
caption_attribution_description: English: This is a picture of the judge who delivered the opinion in the case described in the WP article--Neilson v Harford
context_page_description: Neilson v Harford 151 ER 1266 is a 19th-century English patent law decision that several United States Supreme Court patent law opinions rely upon as authority. The question, as Baron Alderson posed it, was “[W]here is the difference between claiming a principle, which is to be carried into effect any way you will, and claiming a mere principle?” The answer, as the opinions of the various courts that have considered the matter develop, is nowhere.
context_section_description: The Exchequer Court rejected the argument made by the defendants that the patent merely covered the principle that furnace temperature could be increased by injecting hot air instead of cold air into the furnace, for the principle of itself could not be patented. It ruled instead that the patent covered the use of the heated chamber. Baron Parke observed,
  We think the case must be considered as if, the principle being well known, the plaintiff had first invented a mode of applying it by a mechanical apparatus to furnaces; and his invention then consists in this — by interposing a receptacle for heated air between the blowing apparatus and the furnace. In this receptacle he directs the air to be heated by the application of heat externally to the receptacle, and thus he accomplishes the object of applying the blast, which was before of cold air, in a heated state to the furnace.
caption: Baron Parke delivered the opinion of the court in this case
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