Self-induction--mutual induction--=primary induction coils=-- =secondary induction coils=--plain secondary induction coils--secondary induction coils with vibrator and condenser; =cycle of action=--magnetic vibrators--vibrator adjustment-- table of induction coil dimensions--table of sparking distances in air--=points relating to induction coils=--wiring diagram. =THE DYNAMO= =155 to 160= Operation--=essential parts=--field magnets--armature-- =construction of dynamos=--parts; bed plate, field magnets, armature, commutator, brushes. =THE DYNAMO: BASIC PRINCIPLES= =161 to 170= =Definitions=--essential parts--=elementary alternator=-- operation--direction of induced current--application of Fleming’s rule--cycle of operation--=the sine curve=; its construction and application. =THE DYNAMO: CURRENT COMMUTATION= =171 to 180= How the current is produced--=how direct current is obtained=-- the commutator--inductors--“continuous current”--action of four coil elementary dynamo--=conditions for steadiness of the current=. =CLASSES OF DYNAMO= =181 to 198= Classification--bipolar and multi-polar dynamos--difference between dynamo and magneto--self-exciting dynamo--=the series dynamo=--regulation of series dynamo; difficulties experienced-- =the shunt dynamo=--adaptation--operation--characteristic-- regulation--=the compound dynamo=--service intended for-- regulation--over compounding--usual degree of over compounding-- short shunt--long shunt--voltage of short and long shunt machines --separately excited dynamos--=Dobrowolski three wire dynamo.= =FIELD MAGNETS= =199 to 220= =Object=--essential parts--=classes of field magnet=--multi-polar field magnets--construction--choice of materials--design--=pole pieces=--eddy current--=laminated fields=--construction to reduce reluctance of the magnetic circuit--magnetizing coils--=methods of winding=--coil ends--insulation--attachment of coils--coil connections--=heating=--ventilation. INTRODUCTORY CHAPTER The subject matter of this work relates to one of the secrets of creation which appears to have been intended at the very beginning to be “sought out.” This idea is expressed in a certain saying copied three or four thousand years ago by the men of Hezekiah, King of Judah: from Solomon’s proverbs: “_It is the glory of God to conceal a thing: But the glory of Kings_ (i.e., _wise men_), _to search out a matter._”