Patent US679890A successfully refreshed from Google Patents.
US679890A
Expired / Lapsed
US
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Apparatus for measuring errors of refraction in the human eye.
Assignee: Individual
•
Filing: 1900-07-18
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Granted: 1901-08-06
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Expires: 1920-07-18
Abstract
No abstract record available.
Inventors
- 👤 Louis L Ferguson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 05:11
CPC Classifications
A; A61; A61B; A61B3/00; A61B3/02; A61B3/028; A61B3/04
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1904-08-05 | 1905-02-04 | 1905-08-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1908-08-05 | 1909-02-04 | 1909-08-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1912-08-05 | 1913-02-04 | 1913-08-06 | $7700.00 | Window Closed / Lapsed |