## Facts

- Francis C. Lowell, as assignee of Jacob Perkins, sued Winslow Lewis, assignee of James Baker, for infringement of Perkins’s 1813 patent covering an improved pump construction.
- Perkins’s design sought to eliminate the “box” used in common pumps to increase the waterway by configuring valves to occupy essentially the full shaft area while leaving maximum space for water flow.
- Perkins’s pump used triangular valves suited to a square-form pump and was especially useful where large volumes of water were needed quickly with multiple operators.
- Baker’s later pump similarly used valves occupying essentially the full shaft area, but fitted to a round shaft and supported by a brass rim to reduce friction against the shaft’s sides; Perkins had later addressed friction by adding a checkbolt.
- Baker’s pump could be worked by fewer hands and was suitable for common household pumping applications.
- Lewis defended by arguing (1) Perkins’s invention was not new, (2) it was not useful, (3) the patent specification was insufficient, and (4) Baker’s pump was substantially different and therefore non-infringing.
- The court, through Justice Joseph Story’s jury charge, emphasized that the patentee had the burden to prove validity and infringement; the patent grant itself was only slight prima facie evidence.

## Issues

1. In an infringement action, what must the patentee prove regarding novelty and utility, and what evidentiary weight does the patent grant carry?
2. What standard satisfies the statutory “useful” requirement for patentability?
3. When do differences in form or additional features avoid infringement, as opposed to constituting infringement by substantial similarity in principle and structure?
4. If infringement is found, how should damages be measured under the Patent Act, including the role of trebling?

## Decision

- The court instructed that the plaintiff could recover only by proving the patented machine was new and useful; the patent was merely slight prima facie evidence on those points.
- The court rejected the argument that an invention must have “general utility” or supersede existing devices; utility was met unless the invention was frivolous or harmful to society’s well-being, policy, or morals.
- The court instructed that infringement could be found where the accused pump was substantially the same in principle and structure and pursued the same purpose, even if the defendant’s device included added improvements.
- On damages, the court instructed that the jury should find single actual damages measured by the defendant’s profits attributable to the use of the invention, and the court would treble that amount in the judgment.

## Legal Principles

- In a patent infringement action, the patentee bears the burden to establish validity, including novelty and utility; the patent grant is only slight prima facie evidence.
- “Useful” does not require superiority, widespread adoption, or displacement of existing technology; it requires only that the invention not be frivolous and not be injurious to the well-being, policy, or morals of society.
- Infringement analysis focuses on substantial identity in principle, structure, and purpose; nonessential differences in form or the addition of improvements do not avoid infringement if the core inventive concept is taken.
- Under the governing patent damages regime, the factfinder determines actual (single) damages, commonly tied to the defendant’s profits from use, and the court trebles those damages in entering judgment.

## Conclusion

The case established early federal guidance that patentees must affirmatively prove novelty and non-harmful utility despite the existence of a patent grant, and that infringement turns on substantial similarity in operative principle and purpose rather than exact duplication of form, with damages measured by actual loss or defendant profit and trebled by the court upon judgment.


Lowell v. Lewis, 15 F. Cas. 1018 (C.C.D. Mass. 1817)