Page [64]: changed "exaet" to "exact" ( ... of the exact diameter of the turned ends of the cores ...)
Page [73]: moved comma "Rivetting, is" to "Rivetting is," (Rivetting, is perhaps, the best mode ...)
Page [81]: added hyphen ( ... along the short length of wire to the right-hand binding-screw ...)
Page [83]: changed "head" to "heads" ( ... the possible defects of electric bells may be classed under four heads: ...)
Page [92]: changed "its" to "it" ( ... until it rests against the stop or studs.)
Page [102]: changed "contract-breaker" to "contact-breaker" (When the contact-breaker is used, ...)
Page [103]: changed "instead" to "Instead" (Instead of the armature and clapper ...)
Page [132]: in the Morse code for "BRING THE", the code for "H" has been corrected from two dots to four dots.
Page [136]: changed "eletro-magnet" to "electro-magnet" ( ... if the electro-magnet were energised ...)
Page [137]: changed "idicator" to "indicator" (since the indicator falls forwards)