The book was digitized by Google, and published on Google Books.
I use Microsoft OneNote for the OCR, just copy the picture to OneNote, and right click the image, and 'Copy Text from Picture'. Of course you can also copy text direct from Google Books, which is quite comfortable for you to read on a computer screen.
The letter s( ſ ) and f are very confusing, and cause OCR errors. This long minuscule letter s appears in the middle or at the beginning of a word, the letter also called medial, or descending s. The double s in the middle of a word was also written with a long s and a short s.