hyphenation, spelling and grammar have been preserved as in the original
minor punctuation changes made without notes
Page 5, and specimens. focal length. ==> and specimens.
Page 10, will suffice tho show ==> will suffice to show
Page 15, eye-pieces may he changed ==> eye-pieces may be changed
Page 17, movement on Stands AI, Ia ==> movement on Stands A, I, Ia
Page 22, the purpore of modifying ==> the purpose of modifying
Page 25, in tis central portion ==> in its central portion
Page 26, has the folloving advantages ==> has the following advantages
Page 26, is absolutly no limit ==> is absolutely no limit