Makers of Electricity

by Brother Potamian; James J. Walsh

Luigi, or, as he preferred to be known himself, Aloysio Galvani, for the young prince of the house of Gonzaga whose canonization made him St. Aloysius was his patron in baptism and a favorite in life, presents an interesting exemplification of this characteristic trait of the really great discoverer in science, to wait calmly and work faithfully for thorough confirmation of his views before publishing them. His admirable patience in reaching the real significance of his discovery before proclaiming the results of his investigations is only a typical illustration of the modest thorough scientist that he was. It used to be said that Galvani's discovery of the twitchings of the frog's legs, which led him to give himself to serious investigations into animal electricity, was made more or less by accident in 1786. His views on the subject of animal electricity were not formally published until the appearance of his treatise, De Viribus Electricitatis in Motu Musculari Commentarius, in the eighth volume of the Memoirs of the Institute of Science of Bologna, published in 1791. This would seem to indicate that only five years elapsed between his original observation and the publication of his views. Even this interval may seem long enough to our modern notions of at least supposed rapidity of scientific progress, but we know now, from documents in the possession of the Institute of Science at Bologna, that, twenty years previous to the publication of this commentary, Galvani was deeply interested in the action of electricity upon the muscles of frogs, and was diligently and fruitfully occupied during his spare time with investigations upon this subject.

When, in Makers of Modern Medicine,[11] I called special attention to the fact that practically all of the greatest discoverers in medicine had made their cardinal discovery, or at least the far-reaching observation that opened up for them the special career in investigation that was to make them famous, before they were thirty-five, one of my critics doubted the assertion and suggested the case of Galvani as a distinct exception. Ordinarily, it is presumed that his discovery of the twitchings of frogs' legs under the influence of electricity was made in 1786, when he was in his forty-ninth year. As a matter of fact, however, his first observations were made and his attention attracted to the importance of the subject when he was scarcely more than thirty. His career is indeed a striking example of the earliness in life at which a great man's work is likely to come to him, and yet illustrates very aptly the patience with which he devotes himself to it, without seeking the idle reputation to be derived from immediate announcement, if he really has the true spirit of the scientific investigator.

Galvani began original work of a high order very early in his medical career. His graduation thesis on the human skeleton treated especially of the formation and development of bone, and attracted no little attention. It is noteworthy because of the breadth of view in it, for it touches on the various questions relative to osteology, from the standpoint of physics and chemistry, as well as medicine and surgery. It was sufficient to obtain for its author the place of lecturer in anatomy in the University of Bologna, besides the post of director of the teaching of anatomy in the Institute of Sciences, a subsidiary institution. Here, from the very beginning, Galvani's course was popular. He was not, as we note elsewhere, a fluent talker, but he was one of the first who introduced experimental demonstrations of his subject into his lectures, and this made his teaching very attractive and drew crowds to his university courses.

Galvani's work as an anatomist, however, was done much more in comparative anatomy than in the study of the human being. He selected birds for the special subject of his first investigations in the field, and his monograph on the kidneys of birds attracted widespread attention among the scientists of Europe. As the farthest removed from man of the beings that are warm-blooded, these creatures have always attracted particular attention, and, quite apart from any interest in evolution, were the subject of special investigation. Owing to the facility with which they can be studied in embryonic stages in the hatching egg, most of the peculiarities of their structure and development are very well known now. The kidneys of the bird are especially interesting, because they represent a different phase of development from that of human beings. Galvani had selected, then, one of the cardinal or turning-point subjects in comparative anatomy. As he pointed out very clearly, the kidneys of birds differ very much among themselves, and the intense muscular action of this creature makes a large amount of excretory material, that must be disposed of, and consequently demands much more active kidney function than occurs in most other classes of animals. Galvani studied every feature—the vessels, the nerves, the canals—and almost necessarily pointed out many new points or added hitherto unknown details.

He next devoted himself to the study of the ear of the bird. This might seem to be of little special interest, since hearing is not one of the most characteristic qualities of the winged species. It so happens, however, that the semi-circular canals which are closely connected with the auditory apparatus in all animals are extremely large in birds. As a consequence of this, the avian auditory structures assume an importance in comparative anatomy quite like that of the kidneys in the same species. After Galvani had completed his studies, he found that he had been anticipated by another great Italian anatomist of the time, Antonio Scarpa (of Scarpa's triangle in human anatomy), who afterwards became the Chief Surgeon to Napoleon. Galvani abandoned the idea of publishing his book then, but published a short article, in which he added much to Scarpa's details and conclusions. His additions were particularly with regard to the semi-circular canals, which are probably the organ of direction, the necessity for which, in this species, for the purpose of flying, is so easy to understand. He also described with great care the single ossicle or small bone, which replaces the chain of little bones that exist in mammal ears, and pointed out that the shape of this bone and its appendages enabled it to fulfil, though single, all the functions of the hammer, the anvil and the stirrup bones in human beings.

Galvani's careful study of the semi-circular canals of various species of birds can perhaps be better appreciated from the fact that he made it a point to measure their size exactly, as compared to the semi-circular canals of most other creatures. He found that the semi-circular canals of the hawk, for instance, were larger than the corresponding structures in man or even in the cow or the horse. As these latter animals are many hundred times larger than the largest birds, the special significance of the canals in birds becomes manifest. In certain of the birds, as he pointed out, these structures are not semi-circles, nor indeed of circular form at all, but take on much more the shape of an ellipse, and, indeed, sometimes the arc of curvature of the ellipse is quite acute. He seems to have had no hint, however, of the function that we have in modern times assigned to these structures, that of presiding over direction and equilibrium, and discusses in his rather vigorous Latin what the physiological significance of them may be as regards hearing. He thinks that they add something to the acuity of hearing, and would seem to imply that in birds flying rapidly through the air, there was the necessity for a more perfect hearing apparatus than among other creatures, and that this was the reason for the huge development of their semi-circular canals.

At this time the science of comparative anatomy was just beginning to attract widespread attention. John Hunter, in London, was doing a great work in this line, which placed him in the front rank of contributors to biology and collectors of important facts in all the sciences allied to anatomy and physiology. Galvani's work on birds, then, made him a pioneer in the biological sciences that were to attract so much attention during the nineteenth century. His experimental work in comparative anatomy, strange as it might seem, and apparently not to be expected, led him into the domain of electricity, through the observation of certain phenomena of animal electricity and the effects of electrical currents on animals.

Like so many other great discoveries in science, Galvani's first attraction to his subject of animal electricity is often said to have been the result of a happy accident. Of course it is easy to talk of accidents in these cases. Archimedes and his bath; the fall of the apple for Newton; Laennec's observation of the boys tapping on a log in the courtyard of the Louvre and the ready conduction of sound, from which he got his idea for the invention of the stethoscope; Lord Kelvin's eye-glass falling and showing him how a weightless arm for his electrometer might be obtained in a beam of light,—may all be called happy accidents if you will. Without the inventive scientific genius ready to take advantage of them, however, these accidents would not have been raised to the higher plane of important incidents in the history of science. These phenomena had probably occurred under men's eyes hundreds of times before, but there was no great mind ready to receive the seeds of thought suggested, nor to follow out the conclusions so obviously indicated. Galvani's observation of the twitching of the muscles of the frog under the influence of electricity, may be called one of the happy accidents of scientific development, but it was Galvani's own genius that made the accident happy.

There are two stories told as to the method of the first observation in this matter. Both of them make his wife an important factor in the discovery. According to a popular but less authentic form of the history, Galvani was engaged in preparing some frogs' legs as a special dainty for his wife, who was ill and liked this delicacy very much. He thought so much of her that he was doing this himself, in the hope that she would be thus more readily tempted to eat them. While so engaged, he exposed the large nerve of the animal's hind legs, and at the same time split the skin covering the muscles. In doing this he touched the nerve muscle preparation, as this has come to be called, with the scalpel and the forceps simultaneously, with the result that twitchings occurred. While seeking the cause of these twitchings, the idea of animal electricity came to him.

The other form of the story is told a little later in Galvani's own words in the analysis of his monograph on animal electricity. He does not mention his wife in it, but there is a tradition that she was present in the laboratory when the phenomenon of the twitching of the frog's legs was first noticed, and indeed that it was she who called his attention to the curious occurrence.