## Facts

- Harry Leonard obtained a U.S. patent (issued July 5, 1892) covering a multiple-voltage electrical distribution arrangement that enabled different potentials to be supplied from the same source and conductors for use on different service circuits.
- Leonard filed his patent application on November 27, 1891.
- Leonard and Bullock Electric Manufacturing Company, claimed to be Leonard’s (exclusive) licensee, filed a bill in equity against Crocker-Wheeler Co. seeking an injunction and related relief for alleged infringement of the Leonard patent.
- Crocker-Wheeler defended on validity and noninfringement grounds, arguing that Leonard’s patent was anticipated by a Smith patent.
- Smith’s patent application was filed November 11, 1891 (earlier than Leonard’s), and the Smith patent issued March 15, 1892.
- To carry Leonard’s date of invention back before Smith’s November 11 filing date, Leonard introduced a written description of the invention signed by his patent attorney, H. W. Seeley, dated October 3, 1891.
- Seeley had died before the litigation, but two witnesses testified that the signature on the October 3 document was authentic.
- The record included evidence that the time between the October 3 description and Leonard’s November 27 filing resulted from Seeley’s poor health and later death, rather than an intent by Leonard to abandon the invention.
- After addressing the priority/anticipation defense, the court also considered whether Crocker-Wheeler’s accused electrical arrangement fell within the Leonard claims as properly construed.

## Issues

1. Whether Leonard’s patent was invalid as anticipated by Smith’s earlier-filed patent application, or whether Leonard proved an earlier date of invention than Smith’s filing date.
2. Whether a contemporaneous, attorney-signed and dated written description—authenticated by witness testimony despite the attorney’s death—was sufficient corroboration of Leonard’s prior conception.
3. Whether the delay between Leonard’s October 3 conception evidence and his November 27 filing was consistent with reasonable diligence when attributed to his attorney’s illness.
4. If the patent was valid, whether Crocker-Wheeler’s accused multiple-voltage arrangement infringed the Leonard claims.

## Decision

- The court rejected Crocker-Wheeler’s anticipation defense based on the Smith patent.
- The court credited the October 3, 1891 description signed by Leonard’s attorney as strong corroborative evidence that Leonard had conceived the invention before Smith’s November 11, 1891 filing date.
- The court found the document’s authenticity adequately supported by testimony verifying Seeley’s signature and the surrounding circumstances, even though Seeley was deceased.
- The court treated the period before Leonard’s application filing as adequately explained by Seeley’s serious illness and subsequent death, and did not treat the delay as a lack of diligence by Leonard.
- On the merits of infringement, the court concluded that Crocker-Wheeler’s arrangement embodied the same general plan of obtaining plural voltages from a single source and line system, and therefore infringed as to the claims in dispute.
- The court entered a decree for the complainants, granting equitable relief consistent with a finding of valid patent rights and infringement.

## Legal Principles

- Under the pre–first-to-file priority rules, an inventor could defeat an anticipation attack based on an earlier-filed patent by proving earlier conception and reasonable diligence to reduce the invention to practice (including diligence toward filing an application).
- Documentary materials created close in time to the inventive work—such as an attorney-prepared, signed, and dated description made during patent preparation—may corroborate an inventor’s testimony about conception if their authenticity and date are reliably proven.
- When priority depends on antedating another’s filing date, the court evaluates both corroboration of conception and the inventor’s conduct during the critical period; delay attributable to a patent attorney’s serious illness may be consistent with reasonable diligence.
- Infringement analysis focuses on the substance of the claimed arrangement; changes in form, placement, or wiring details do not avoid infringement where the accused device achieves the same result by substantially the same means within the scope of the claims as construed.

## Conclusion

In Bullock Electric Manufacturing Co. v. Crocker-Wheeler Co., the court upheld Leonard’s multiple-voltage electrical patent against an anticipation defense grounded in Smith’s earlier filing by accepting corroborated, attorney-dated evidence of Leonard’s prior conception and by treating the filing delay as reasonably explained by counsel’s illness and death; with validity sustained, the court further found that Crocker-Wheeler’s system fell within the patent’s claims and entered a decree for the complainants.


Bullock Electric Manufacturing Co. v. Crocker-Wheeler Co., 141 F. 101 (1905)