Very silently, in the dark of night, the priests of the Siena cathedral, directed by Abbé Toaldo, laid their iron rods along the walls of the building, but inside, planting them deep into the ground, and with the pointed summit only a few feet above the highest point of the steeple, so as to be scarcely perceptible from below by the naked eye. Still the secret of what had been done could not be entirely kept from the multitude. Some of the workmen, engaged in the operation of fixing the iron rods to the inner walls and steeple of the cathedral, whispered about what they had been doing, trembling at the evil consequences of their work, notwithstanding having received full absolution from their employers. Murmurs were now heard everywhere, and there were signs of a popular outbreak, just when one of the many thunderstorms regularly visiting the mountain city crept over it on April 18, 1777. Portentously the black clouds laid themselves thicker and thicker over the high cathedral, till all the people of Siena crept forth from their houses, awaiting in breathless expectation the terrors to come. Then the dark masses discharged their fiery streams; flash followed flash, till one, a long hissing tongue of flame, fell down upon the cathedral steeple, distinctly visible to thousands of beholders. A few minutes after, a ray of sunshine pierced the dark clouds, and to the bewildering astonishment of the masses, the cathedral was standing there absolutely unhurt. As if to exhibit its wonderful power, the gilded point of the lightning conductor stood out brilliantly in the sun, pointing in radiant silence up to heaven. ‘Maraviglia, maraviglia!’ cried people and priests in chorus. High mass was held forthwith in the wonderfully preserved cathedral, and on the same day the magistrates of Siena went into the town hall and had a record made in the book containing the annals of the city, to make known to all posterity that their noble cathedral had just been preserved from destruction by the astounding influence of an ‘heretical rod.’ Though not in the least intended to be sarcastic, the irony could not have been more complete.
There was a most remarkable historical concurrence between the gradual introduction of lightning conductors into Europe and that of the art of vaccination. Both the great scientific discoveries had the same end in view for the benefit of mankind, the one teaching the art of drawing the dangerous electric fire of the clouds harmlessly into the earth, and the other that of extracting the poisonous seed of disease from the human body. Both were brought forward with the noblest intentions; and both encountered the most violent opposition from religious fanatics, the same in substance, as interfering with the decrees of Providence, and the ordained wrath of heaven. Both triumphed in the end, and almost exactly at the same time, though the battle of the great medical discovery lasted longer, and was more fiercely fought than that of Franklin’s invention. To make the analogy between the progress of lightning conductors and of vaccination complete, it so happened that in at least one conspicuous instance the same man was an important agent in forwarding the success of both discoveries. The person in question was Dr. Johan Ingenhousz, a native of Breda, in the Netherlands, born in 1730. A man of great natural gifts, he came to England when about thirty years of age, practising as a physician, and attending specially to the so-called Suttonian method of inoculation against the small-pox, then an entirely new branch of medical science. At the same time he eagerly embarked in electrical experiments, got into correspondence with Benjamin Franklin, and, having made many friends, was elected a fellow of the Royal Society in 1769. Recommended to the king, Dr. Ingenhousz became a favourite at court, owing chiefly to his perfect knowledge of German, which resulted in his being recommended to a highly profitable as well as distinguished mission. The famous Imperial lady, the Elizabeth of her age, Maria Theresa of Austria, had read of the benefits of vaccination, then chiefly known in England, and wishing to confer them on her own family and friends, she asked King George the Third to recommend to her some able physician, who could come to Vienna for the purpose. His Majesty at once named Dr. Johan Ingenhousz, a recommendation warmly supported by the President of the Royal Society, Sir John Pringle, who had taken an affection for the young Dutch physician on account of his electrical researches, which had resulted in the invention of a novel apparatus, subsequently known as the plate electrical machine.