Among the many inventions attributed to Hypatia, besides the planisphere and astrolabe which she designed for the use of astronomers, are several employed in the study of natural philosophy. Probably the most useful of these is an areometer mentioned by her pupil Synesius. He calls it a hydroscope and describes it as having the form and size of a flute, and graduated in such wise that it can be used for determining the density of liquids. That Hypatia was thoroughly familiar with the science of natural philosophy, as then known, there can be no doubt. That she also contributed materially to its advancement, as well as to that of astronomy, in which she always exhibited a special interest, there is every reason to believe.[153]
After the death of Hypatia, the study of natural philosophy was almost entirely neglected for more than a thousand years. The first woman in modern times to attract attention by her discussion of physical problems was the famous Marquise du Châtelet, although she was better known as a mathematician and as the translator into the French of Newton's Principia. In her château at Cirey she had a well-equipped physical cabinet in which she took special delight. But in her time, as in that of Hypatia, natural philosophy was far from being the broad experimental science which it has become through the marvelous discoveries made in heat, light, electricity and magnetism during the last hundred years, as well as through those countless brilliant investigations which have led up to our present doctrine of the correlation and conservation of the various physical forces. There was then no occasion for those delicate instruments of precision which are now found in every physical laboratory by means of which the man of science is able to investigate phenomena and determine laws that were quite unknown until a few years ago.
In the time of Mme. du Châtelet, as during the century following, natural philosophy consisted rather in the mechanical and mathematical than in the physical study of nature. This is illustrated by the title of the great work on the translation of which she spent the best years of her life—Newton's immortal Philosophiæ Naturalis Principia Mathematica.
The Marquise's first scientific work was an investigation regarding the nature of fire. The French Academy of Sciences had offered a prize for the best memoir on the subject. Among the contestants for the coveted honor were the chatelaine of Cirey and the celebrated Swiss mathematician, Leonard Euler. The Marquise was unsuccessful in the contest, but her paper was of such value that the eminent physicist and astronomer, Arago, was able to characterize it as an "elegant piece of work, embracing all the facts relating to the subject then known to science and containing among the experiments suggested one which proved so fecund in the hands of Herschel." In this remarkable Mémoire sur le Feu, which is printed in the Collections of the Academy, the Marquise anticipates the results of subsequent researches of others by maintaining that both heat and light have the same cause, or, as we should now say, are both modes of motion.
The second book written by this remarkable woman is entitled Institutions de Physique, and was dedicated to her son, for whose benefit it was primarily written. It deals specially with the philosophy of Leibnitz and discusses such questions as force, time and space. Her views respecting the nature of the force called vis viva, which was much discussed in her time, are of particular interest, as they are not only opposed to those which were held by Descartes and Newton, but also because they are in essential accord with those now accepted in the world of science.
All things considered, the Marquise du Châtelet deservedly takes high rank in the history of mathematical physics. In this department of science she has had few, if any, superiors among her own sex. And, when we recollect that she labored while the foundations of dynamics were still being laid, we shall more readily appreciate the difficulties she had to contend with and the distinct service which her researches and writings rendered to the cause of natural philosophy among her contemporaries.
The first woman to occupy a chair of physics in a university was the famous daughter of Italy, Laura Maria Catarina Bassi. She was born in Bologna in 1711—but five years after the birth of Madame du Châtelet—and from her most tender years she exhibited an exceptional facility for the acquisition of knowledge.
After she had, through the assistance of excellent masters, become proficient in French and Latin, she took up the study of logic, metaphysics and natural philosophy. In all these branches of learning her progress was so rapid that it far exceeded the fondest expectations of her parents and teachers. Thanks to a wonderful memory and a highly developed reasoning faculty, she was able, while still a young maiden, to prove herself the possessor of knowledge that is ordinarily obtained only in the maturity of age and after long years of systematic study.
When she had attained the twenty-first year of her age she was induced by her family and friends—much against her own inclination, however—to take part in a public disputation on philosophy. Her entering the lists against some of the most distinguished scholars of the time was made the occasion for an unusual demonstration in her honor. The hall of the university in which such intellectual jousts were generally held was too small for the multitude that was eager to witness the young girl's formal appearance among the scholars and the notables of the old university city. It was, accordingly, arranged that the disputation should be held in the great hall of the public Palace of the Senators.
Among the vast assemblage present at the disputation were Cardinal Grimaldi, the papal legate; Cardinal Archbishop Lambertini, afterwards Pope Benedict XIV; the gonfalonier, senators, literati from far and near, leading members of the nobility and representatives of all the religious orders.