# Tyler v. Boston

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United States Supreme Court
74 U.S. 327
Tyler v. Boston
TYLER brought suit, in the Circuit Court for Massachusetts, against the city of Boston, for infringement of a patent; the case being this:
The plaintiff professed to have discovered a new compound substance, being a combination of fusel oil with the mineral and earthy oils, which compound constitutes a burning fluid, 'by which term,' he says, 'I mean a liquid which will burn for the purpose of illumination, without material smoke, in a lamp with a small solid wick, and without a chimney.'
The claim of his patent which the defendant was charged with infringing, was 'the compound produced by the combination of the mineral or earthy oils with fusel oil, in the manner and for the purpose substantially as herein set forth; said compound constituting a new manufacture.'
The component parts of this new manufacture were described as 'by measure crude fusel oil one part, kerosene one part.' This combination, the patent stated, might be varied by the substitution of naphtha or crude petroleum in place of Kerosene, or a part of the kerosene by an equal quantity of naphtha or crude petroleum; 'the exact quantity of fusel oil which is necessary to produce the most desirable compound must be determined by experiment.'
The defendants used a burning fluid composed of naphtha seventy-two and fusel oil twenty-eight parts; and experts, chemists, proved that seventy-two parts in bulk of naphtha was the substantial equivalent of twenty-eight parts of kerosene.
The court below charged the jury, 'that the patentee, in suggesting that naphtha might be substituted for kerosene, intended to describe the same proportion in the combination,' and 'that the jury should understand the construction of the suggested substitution, to wit, naphtha for kerosene, as contemplating the same proportion of the two ingredients-that is, one and one, or fifty per cent. of one, and fifty per cent. of the other.'
It charged further, that 'whether one compound of given proportions is substantially the same as another compound varying in the proportions-whether they are substantially the same or substantially different-is a question of fact, and for the jury.'
Under this charge the jury found for the defendant; and the case was now here on error.
Mr. Maynadier, for the plaintiff in error, contended, that the construction given by the court to the patent was erroneous, and that in view of the evidence as to the true relations and characters of the various oils, the claim should be construed to cover not only a compound composed of the particular ingredients in the proportionate bulks especially named in the specification (that is to say, crude fusel oil, one part by measure, and kerosene of the grade there described, one part by measure), and all other compounds composed of these ingredients in substantially the same proportionate bulks; but, in addition, all other compounds whose ingredients are any of the earthy or mineral oils, and any of the fusel oils, provided the quantity by measure of the mineral oil or oils used were ascertained to be substantially equal in character, or equivalent to the prescribed proportion of the prescribed grade of kerosene; and the quantity by measure of the fusel oil used were in like measure ascertained to be equal to the prescribed proportion of the prescribed crude fusel oil.
The whole spirit of the patent, in view of the perfectly well-known relations of naphtha and kerosene, and of refined and crude fusel oil, warrants the construction contended for, and there is nothing in the letter which militates against it, unless the statement that 'a part of the kerosene may be replaced by an equal quantity of naphtha or crude petroleum' be construed to mean an equal quantity in bulk, which would make the statement false, and one that all persons skilled in the art would know to be false; while if 'equal' be construed to mean 'equal in character,' or 'equivalent,' the statement is true, and in harmony with the rest of the specification, and with the chemical facts of the case.
Mr. Robb, contra:
The instruction given was correct. The language used by the patentee in describing his invention and the manner of compounding the same, is 'full, clear and exact,' in view of that construction adopted by the court below. To give it the construction contended for by the plaintiff, the obvious import of the terms used must be disregarded, and the same word must be taken in different senses, in the same sentence; that is, the word 'quantity,' when used in reference to fusel oil, alcohol, or kerosene, means measure; but when used in reference to naphtha or petroleum, it must be taken to mean weight.
Mr. Justice GRIER delivered the opinion of the court.

## Notes

This work is in the public domain in the United States because it is a work of the United States federal government (see 17 U.S.C. 105).
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