Makers of Electricity

by Brother Potamian; James J. Walsh

She was a woman of well-developed intellect, and her association with her father and also with her husband made her well acquainted with the anatomy and physiology of the day. She realized that what had occurred was quite out of the ordinary. She is even said to have suggested their possible connection with the presence and action of the electric apparatus. Husband and wife, then, together, by means of a series of observations determined that, whenever the apparatus was not in use the phenomenon of the convulsive movements of the frog's legs did not take place, notwithstanding irritation by the scalpel. Whenever the electric apparatus was working, however, then the phenomenon in question always took place. According to either form of the story, if we accept the traditions in the matter, Madame Galvani had an important part in the discovery.

Galvani's most important contribution to science is undoubtedly his De Viribus Electricitatis in Motu Musculari Commentarius—Commentary on the Forces of Electricity in Their Relation to Muscular Motion. Like many another epoch-making contribution to science, it is not a large work, but in his collected works in the edition of 1841, occupies altogether sixty-four pages, of scarcely more than two hundred and fifty words to the page. There are probably not more than fifteen thousand words in it altogether. It was published originally in the eighth volume of the Memoirs of the Institute of Science at Bologna, in 1791, but a reprint of it, with some modifications, was issued at Modena in the following year. This Modenese edition, published by the Societa Typographica, was annotated by Professor Giovanni Aldini, who also wrote an accompanying dissertation, De Animalis Electricae Theoriae Ortu Atque Incrementis, On the Rise and Development of the Theory of Animal Electricity. In this volume was also published a letter from Galvani to Professor Carminati, in Italian, on the Seat of Animal Electricity. These two editions are the sources to which we must turn for whatever Galvani tried to make known with regard to animal electricity.

This little volume consists of four parts: the first of which is devoted to a consideration of the effects of artificial electricity on muscular motion; the second is on the effect of atmospheric electricity on muscular motion; the third is on the effect of animal electricity on muscular motion; and the fourth consists of a series of conjectures and some conclusions from his observations. The arrangement of the work, as can readily be understood from this, is thoroughly scientific. Galvani proceeds from what was best known and most evident to what he knew less about, trying to enlarge the bounds of knowledge and then suggesting the conclusions that might be drawn from his work and offering a number of hints as to the possible significance of many of the phenomena that might form suggestive material for further experimentation along this same line. In spite of the forbiddingness of the Latin to a modern scientist, as a rule, the little work is well worthy of study because of its eminently scientific method and the excellent evidence it affords of the way serious students of science approached a scientific thesis before the beginning of the nineteenth century.

The first paragraph of this dissertation is of such fundamental significance, because it represents the primal work done in animal electricity, that it has seemed to me worth while presenting entire. The original Latin from which the translation is made, and from which a good idea of Galvani's Latin style may be obtained, is given in a note.[12]

"I had dissected a frog and had prepared it, as in Figure 2 of the fifth plate (in which is shown a nerve muscle preparation), and had placed it upon a table on which there was an electric machine, while I set about doing certain other things. The frog was entirely separated from the conductor of the machine, and indeed was at no small distance away from it. While one of those who were assisting me touched lightly and by chance the point of his scalpel to the internal crural nerves of the frog, suddenly all the muscles of its limbs were seen to be so contracted that they seemed to have fallen into tonic convulsions. Another of my assistants, who was making ready to take up certain experiments in electricity with me, seemed to notice that this happened only at the moment when a spark came from the conductor of the machine. He was struck with the novelty of the phenomenon, and immediately spoke to me about it, for I was at the moment occupied with other things and mentally preoccupied. I was at once tempted to repeat the experiment, so as to make clear whatever might be obscure in it. For this purpose I took up the scalpel and moved its point close to one or the other of the crural nerves of the frog, while at the same time one of my assistants elicited sparks from the electric machine. The phenomenon happened exactly as before. Strong contractions took place in every muscle of the limb, and at the very moment when the sparks appeared, the animal was seized as it were with tetanus."

Galvani then explains in detail how he made observations on control frogs at moments when there were no electric sparks, and decided that the contact with the scalpel was only effective in producing twitchings when there was a simultaneous electric spark. He noted, also, that occasionally the contractions did not occur, in spite of the fulfilment of the conditions mentioned. He traced this to fatigue. He then proceeded to vary the experiment in many ways, decreasing the size of the scalpel, increasing and decreasing the size of the electric machine and varying the method of preparation of the frog, so as to decide just what the significance of the phenomenon was. In a general way, it may be said that this study shows Galvani as one of the most careful of experimentalists, though he has often been declared to be a theorizer, rather than an observer.

A very interesting anticipation of Galvani's original experiment, made long before his time by a great naturalist, the story of which serves to show that discoveries made before their time, that is, before people are ready to follow them up, fail to attract attention, has been called to my attention by Brother Potamian. In the second volume of the Dutch Naturalist Swammerdam's Works, page 839, is to be found the following passage:[13] "Another experiment that is at once very curious and suggestive can be made if one separates the largest of the muscles of the thigh of the frog and so prepares it with its adherent nerve as to leave it unhurt. If after this has been done you take the tendons of this muscle, one in each hand, and irritate the hanging nerve by a little forceps or other instrument, the muscle will recover the former motion which it had lost. You will see at once that it contracts and that there will be an effort as it were to bring together the two hands which hold its tendons. This I demonstrated, in the year 1658, to the illustrious Duke of Tuscany then reigning, when he was at the moment in a state of mind that prompted him not to favor me. This same experiment can be repeated with the same muscle as often and for as long a time as any portion of the nerve remains uninjured, so that we may, therefore, irritate the muscle to its former contraction as often as we wish."

As a foundation classic in electricity, Galvani's De Viribus Electricitatis deserves more detailed analysis. The first part of the monograph is taken up with experiments of many kinds, with what may be called artificial sources of electricity—the electric machine, the Leyden jar, and other modes of electrical development. The second part treats of the effects of atmospheric electricity upon muscular motion, by which expression Galvani means lightning, though he also observed various electrical manifestations in the muscles of his frogs when there was no actual lightning but only darkening of the heavens, without actual passage of the current flash from one cloud to another or from the clouds to the earth. In this matter, Galvani displayed quite as much courage as patient observation. He knew the fate of Richmann, the Russian scientist, who had been struck dead by a lightning-bolt while making experiments not very different, yet he dared to place a lightning conductor on the highest point of his house, and to this conductor he attached a wire, which ran down to his laboratory. During a storm, he suspended on this metallic circuit, by means of their sciatic nerves, frogs' legs and the legs of other animals prepared for the purpose. To the feet of the animals he attached another Wire sufficiently long to reach down to the bottom of a well, thus grounding the circuit.

Not satisfied with this study of the influence of lightning and large electrical disturbances in the air on the preparation of the frog as he had made it, Galvani set about discovering whether even the slight differences in electrical potential which occur during the day in atmospheric electricity might not give rise, even in fair weather, to certain contractions of the frog's muscles. He made his observations for many days at many different hours and under varying conditions of light and shade, of heat and cold, without finding anything. There were occasional contractions, but they bore no definite relation to variations in the atmosphere, or the electric state of the atmosphere. Galvani satisfied himself of this very thoroughly, and with a patience and diligence worthy of emulation by a Fellow at a modern university working on a foundation for the determination of a particular question.

The third part of the work is the most important as well as the longest, and contains the ideas which are original with Galvani, but which met most opposition in his time and have only been properly appreciated in recent years. Galvani came to the conclusion that there is such a thing as animal electricity. This led to a famous controversy with Volta, in which their contemporaries judged that Galvani had the worst of it; but, as so often happens, their successors a century later would judge that Galvani's views were more in accord with what we know at the present time. Criticism is always easier than scientific advance, and in a controversy it is usually the man who writes most forcibly, rather than the one who thinks most deeply, who secures the assent of readers. This makes controversy in matters of science always unfortunate, for it does much more to retard than to help scientific progress.