| Keyword | count | density % |
|---|---|---|
| microscope | 121 | 9.15 |
| london | 36 | 2.72 |
| model | 36 | 2.72 |
| microscopes | 23 | 1.74 |
| antique | 18 | 1.36 |
| optical | 18 | 1.36 |
| binocular | 15 | 1.13 |
| bausch | 14 | 1.06 |
| lomb | 14 | 1.06 |
| leitz | 12 | 0.91 |
| york | 12 | 0.91 |
| wetzlar | 11 | 0.83 |
| improved | 9 | 0.68 |
| large | 8 | 0.6 |
| petrological | 8 | 0.6 |
| made | 8 | 0.6 |
| monocular | 8 | 0.6 |
| early | 7 | 0.53 |
| paris | 6 | 0.45 |
| swift | 6 | 0.45 |
| ross | 6 | 0.45 |