The measurement of induction shocks; a manual for the quantitative use of Faradic stimuli
Ernest Gale Martin · 1912
Introductory.The inductorium has become one of the most familiar and most useful instruments in the physiological laboratory.There are few physiological researches which do not involve artificial stimulation of tissues; and for the production of stimuli induction shocks are in most cases the first choice.They are easier to use and they subject the stimulated tissue to less permanent modification than do other forms of artificial stimulus.Induction shocks are, however, very variable in intensity; and as commonly used there is no means of knowing or of stating their physiological effectiveness in other than the most general terms.An induction shock is weak, medium, or strong.More closely than that the user does not attempt to describe it.This lack of knowledge as to the strengths of the stimuli employed is often a serious handicap in the pros- ecution of individual researches, particularly such as call for the use of stimuli of varying strengths.It also INDUCTION SHOCKS operates to make uncertain the attempts of investigators to duplicate the experiments of others.No one will question the desirability of being able to measure f aradic stiniuli, both for the sake of controlling the stimuli used iii pne's own experiments, and also in orrier 'tjiart ^these/'.s.tiniuli may be so described as to enable other workers to duplicate them as occasion arises.The purpose of this work is to outline a system for calibrating the apparatus used in generating induction shocks, so that the value of the shocks may be expressed in terms of stimulation units; these units to be appli- cable to any properly constructed induction apparatus, and to be based upon determinations which can be made in any ordinarily equipped physiological laboratory.The system proposed is not a new departure, but is an extension and amplification of previous systems.Historical.The phenomenon of electromagnetic in- duction was discovered by Faraday in 1831, and its physical characteristics were very thoroughly worked out by him and by Henry about the same time.The first suggestion for the physiological use of induction shocks appears to have been made by Sturgeon* hi 1837, and from that time to the present their use in this connection has continued.Various forms of induction apparatus have been de-