Books like Egyptian Grammar
Sir Alan Gardiner
Egyptian Grammar is 646 pages, about 11 hours 51 minutes at 250 words a minute.
7 books to read next
How long each takes
How to Read Egyptian Hieroglyphs 3.5 h 
Egyptian Language 4.5 h Late-Egyptian Miscellanies 11.2 h 
Reading Egyptian Art 4.1 h 
Teach Yourself Hieroglyphics 2.6 h 
Egyptian Hieroglyphs for Complete Beginners 2.9 h 
Decoding Egyptian Hieroglyphs 3.2 h Bar height shows length. Estimated at 250 words a minute.