S\VINDEN, VAN, J. II. a celebrated natural philosopher, was born at the Hague, on the 8th June His father, an eminent barrister, in tended to bring up his son to the same profession, and with this view he watched his early education with the tenderest care. The young Van Swin den, however, soon showed a disposition to studies of a different kind; and he took peculiar delight in calculating, drawing, watch-making, and mechani cal pursuits. At an early age he was sent to the university of Leyden, where he had the good for tune of meeting with Mr. Hennert, then private lecturer in Leyden, and a staunch Eulerian analyst, who initiated his friend into all the intricacies of the modern calculus.
At the early age of twenty (1767), when he was called to the chair of natural philosophy in the uni versity of Franeker, he opened his lectures with a discourse, De causes errorum in rebus philosophicis.
At Franeker, the tranquillity of a small town gave full scope to his ardour for study. Ile would often not stir from home for weeks together, and all his time was divided between his closet, his pu pils, and his observations. This overstraining of his faculties had its usual effects; his health was impaired, and the mineral waters of Spa, Aix-la Chapelle, Pyrmont, were frequently resorted to, in order to restore his strength, and above all, to drive him from his studies.
The subjects of meteorology, electricity, and magnetism, then particularly engaged his atten tion; and he applied himself with unremitting zeal to such observations as were likely to throw some new light on these interesting subjects. Amongst his earliest writings, is his Tentamen de Magnete, published in 1772, in which he exposes his mathe matical theory of what he calls the punctum cul minans.
During the long space of ten years, the mag netic variation was actually observed every hour of the day by M. Van Swinden or his pupils. With equal care, during thirteen years, he kept an exact register of the barometer, thermometer, and hy grometer. No circumstance relating to atmos pheric phenomena escaped his attention; no aurora borealis appeared during his residence in Franc ker but what. was accurately observed. Parts of
his house and garden were arranged as an observa tory. His friends, his pupils, even his servants, sustained the parts of observers during such ab sences as he was compelled to make. Even in other parts of the country he procured observers, to whom he gave directions and encouragement. By these means, he collected an immense number of facts relating to the subjects of his investigation, whilst by unremitting study, and an excellent memory, he acquired a degree of learning which may almost be said to be unrivalled.
His Recherches sur les aiguilles aimant(es, to which the Academy of Sciences of Paris adjudged the prize, (1777,) contain such a vast number of observations, and such a variety of curious facts relating to magnetical phenomena, as are seldom found in any writer on natural philosophy. When the Academy of Bavaria (1776) proposed as a prize question the investigation of the analogy between magnetism and electricity, Van Swindell received the program so late as to leave him only a few days to prepare an answer to the question. But he had thoroughly considered the subject. The experi ments required had been made long before; and the first medal was awarded to him. This paper, to gether with some others on the same subject, he translated afterwards from Latin into French; and they are well known to philosophers under the title of Memoirs sur r.dnalogie de l'Electricite et du Ilkignetisme, 1784.
The Journal de Physique, the Journal des Savants, the Memoirs of the Academies of Berlin, Paris, of the Royal Society, of the Academics of Turin, Brussels, Haarlem, Petersburg, contain many of his papers. When Charles Bonnet's Contempla tions de la Nature were translated into Dutch, M. Van Swindell made many additions and notes, which Bonnet judged so important as to have them inserted in subsequent French editions of his work.