[49] It is said that Kepler saw this dark spot while looking at the sun in a camera obscura. As a camera obscura is actually a telescope, magnifying objects in proportion to the focal length of the lens employed, he may be said to have first seen these spots with the aid of an optical instrument.
Transcriber’s Notes and Errata
The following typographical errors were corrected:
| Page | Error | Coorection |
| 50 | betwen | between |
| 71 | his his | his |
| 100 | secretry | secretary |
| 143 | there sidence | the residence |
| 234 | guaging | gauging |