Diseases of the soft structures of the teeth and their treatment; a text-book for students and practitioners . Fi<;. 112.—The S. S. White current controller. which guides the operator in his work, consequently too muchemphasis cannot be placed upon the importance on obtaining aperfect working Fig. 113.—Weston milliamperemeter. At this point the writer may be permitted to digress for a momentfrom the subject proper and call to the mind of the reader the funda-mental nomenclature governing electrical measurements—as far asit is utilized in the following discussion. By the term am
Diseases of the soft structures of the teeth and their treatment; a text-book for students and practitioners . Fi<;. 112.—The S. S. White current controller. which guides the operator in his work, consequently too muchemphasis cannot be placed upon the importance on obtaining aperfect working Fig. 113.—Weston milliamperemeter. At this point the writer may be permitted to digress for a momentfrom the subject proper and call to the mind of the reader the funda-mental nomenclature governing electrical measurements—as far asit is utilized in the following discussion. By the term ampere is 206 DISEASES OF THE DENTAL PULP meant the unit of strength of a current. A milliampere ispart of an ampere, expressed as A volt is the measurthe unit of pressure of the current, I e., the electric power necessarpto drive a current of 1 ampere through a resistance of 1 ohm. It isreferred to as the electro-motive force and expressed as ohm measures the resistance of a circuit through which a currentflows and a watt represents the units of power. The currentstrength flowing in a circuit is equal to the pressure divided by the
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