A · How many
Share of extension entries
36Extension entries
Key point
Extension entries number 36, 0.25% of all entries; the decade with most is the 1840s (13).
- Definition
- Share of Woodcroft's numbered entries that grant an extension or confirmation of an earlier patent, by decade.
- Formula
- extension entries ÷ entries
- How to read it
- Extensions are rare: under 1% of all entries.
- Caveats
- Counts entries whose text contains 'extension', 'prolongation' or 'confirmation'. The 36 numbers whose text the OCR lost cannot be checked; they stay in the denominator as entries that are not extensions, so the share is a lower bound (0.50% of all entries even if all 36 were extensions).
Table
Download CSV · m_a4_extensions.csv
| Decade | Entries | Extensions | Share |
|---|---|---|---|
| 1610 | 15 | 0 | 0.0% |
| 1620 | 33 | 0 | 0.0% |
| 1630 | 75 | 0 | 0.0% |
| 1640 | 4 | 0 | 0.0% |
| 1660 | 31 | 0 | 0.0% |
| 1670 | 51 | 1 | 2.0% |
| 1680 | 53 | 0 | 0.0% |
| 1690 | 102 | 0 | 0.0% |
| 1700 | 22 | 0 | 0.0% |
| 1710 | 38 | 0 | 0.0% |
| 1720 | 89 | 0 | 0.0% |
| 1730 | 56 | 0 | 0.0% |
| 1740 | 82 | 0 | 0.0% |
| 1750 | 92 | 0 | 0.0% |
| 1760 | 205 | 0 | 0.0% |
| 1770 | 294 | 0 | 0.0% |
| 1780 | 477 | 0 | 0.0% |
| 1790 | 647 | 0 | 0.0% |
| 1800 | 924 | 1 | 0.1% |
| 1810 | 1,136 | 1 | 0.1% |
| 1820 | 1,452 | 1 | 0.1% |
| 1830 | 2,452 | 12 | 0.5% |
| 1840 | 4,581 | 13 | 0.3% |
| 1850 | 1,448 | 7 | 0.5% |
ocrReliability card
OCR count: counted by rule from scanned OCR text; below, the error measured on a sample checked against page images
- Image check, year
- 119/120 (99%, 95% CI 95–100%)
- Image check, term
- 118/120 (98%, 95% CI 94–100%)
- Image check, number of grantees
- 118/120 (98%, 95% CI 94–100%)
- Image check, communication
- 119/120 (99%, 95% CI 95–100%)
Sources
- Bennet Woodcroft, Titles of Patents of Invention, Chronologically Arranged, from March 2, 1617 (14 James I.) to October 1, 1852 (16 Victoriae), London: Eyre & Spottiswoode, 1854, 2 parts (Nos. 1–14,359). Entries were split from the word coordinates of the Internet Archive OCR of the University of Illinois copy (
chronologicalin1617grea_0,chronologicalind1617grea); 115 pages on which that OCR lost entry numbers were read again from the page images with tesseract 5. (public domain, 1854; https://archive.org/details/chronologicalin1617grea_0)