Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Indeed mostly useless

Alas a have to join the last reviewer in most of his remarks. Though I liked the Analemma part which was quite interesting and somewhat useful, there is nothing in it which would help you in navigating with a sextant. The rest is indeed a collection of noncoherent sentences and topics. Might be interesting for a child but my advice for everyone else interested in celestial navigation is buy a better book