(Humphry) an eminent mathematician, was born at Salisbury, May 29, 1675. Being an only son, and his father observing in him an extraordinary good capacity, determined to cultivate it with a good education. For this purpose he placed him in a reputable private academy; upon quitting of which he, at the desire of his father, though against his own inclination, engaged in the profession of divinity, and began to exercise his function at Tunbridge in the county of Kent, where he continued to preach some years; during which time he married a lady of that place.
But a weak constitution, and the death of his father, induced Mr Ditton to quit that profession. And at the persuasion of Dr Harris and Mr Whiston, both eminent mathematicians, he engaged in the study of mathematics; a science to which he had always a strong inclination. In the prosecution of this science, he was much encouraged by the success and applause he received: being greatly esteemed by the chief professors of it, and particularly by Sir Isaac Newton, by whose interest and recommendation he was elected master of the new mathematical school in Christ's Hospital; where he continued till his death, which happened in 1715, in the 40th year of his age, much regretted by the philosophical world, who expected many useful and ingenious discoveries from his affability, learning, and penetrating genius.
Mr Ditton published several mathematical and other tracts, as below.—1. Of the Tangents of Curves, &c. Philos. Trans. vol. 23.
2. A Treatise on Spherical Catoptries, published in the Philos. Trans. for 1705; from whence it was copied and reprinted in the Acta Eruditorum 1707, and also in the Memoirs of the Academy of Sciences at Paris.
3. General Laws of Nature and Motion; 8vo, 1705. Wolfius mentions this work; and says that it illustrates and renders easy the writings of Galileo, Huygens, and the Principia of Newton. It is also noticed by La Roche, in the Memoires de Literature, vol. 8, page 46.
4. An Institution of Fluxions, containing the first Principles, Operations, and Applications, of that admirable Method, as invented by Sir Isaac Newton, 8vo, 1706. This work, with additions and alterations, was again published by Mr John Clarke, in the year 1726.
5. In 1709 he published the Synopsis Algebraica of John Alexander, with many additions and corrections.
6. His Treatise on Perspective was published in 1712. In this work he explained the principles of that art mathematically; and besides teaching the methods then generally practised, gave the first hints of the new method afterwards enlarged upon and improved by Dr Brook Taylor; and which was published in the year 1715.
7. In 1714, Mr Ditton published several pieces both theological and mathematical; particularly his Discourse on the Resurrection of Jesus Christ; and The New Law of Fluids, or a Discourse concerning the Acent of Liquids, in exact Geometrical Figures, between two nearly contiguous Surfaces. To this was annexed a tract, to demonstrate the impossibility of thinking or perception being the result of any combination of the parts of matter and motion: a subject much agitated about that time. To this work also was added an advertisement from him and Mr Whiston, concerning a method for discovering the longitude, which it seems they had published about half a year before. This attempt probably cost our author his life; for although it was approved and countenanced by Sir Isaac Newton, before it was presented to the Board of Longitude, and the method has been successfully put in practice, in finding the longitude between Paris and Vienna; yet that board then determined against it: so that the disappointment, together with some public ridicule (particularly in a poem written by Dean Swift), affected his health so that he died the ensuing year, 1715.
In an account of Mr Ditton, prefixed to the German translation of his Discourse on the Resurrection, it is said that he had published, in his own name only, another method for finding the longitude; but which Mr Whiston denied. However, Raphael Levi, a learned Jew, who had studied under Leibnitz, informed the German editor, that he well knew that Ditton and Leibnitz had corresponded upon the subject; and that Ditton had sent to Leibnitz a delineation of a machine he had invented for that purpose; which was a piece of mechanism constructed with many wheels like a clock, and which Leibnitz highly approved of for land use; but doubted whether it would answer on ship-board, on account of the motion of the ship.
DIVING-BELL has been already described in the Encyclopaedia; but in that work was given no account of its antiquity or its invention. In the works of Aristotle we read of a kind of kettle used by divers to enable them to remain for some time under water; but the manner in which these kettles were employed is not clearly The oldest information (says Professor Beckmann) which we have of the use of the diving bell in Europe, is that of John Tainiter, who was born at Hainault in 1509, had a place at court under Charles V., whom he attended on his voyage to Africa. He relates in what manner he saw at Toledo, in the presence of the emperor and several thousand spectators, two Greeks let themselves down under water, in a large inverted kettle, with a burning light, and rise up again without being wet. It appears that this art was then new to the emperor and the Spaniards, and that the Greeks were caused to make the experiment in order to prove the possibility of it.
When the English, in 1588, dispersed the Spanish fleet, called the Invincible Armada, part of the ships went to the bottom, near the isle of Mull, on the western coast of Scotland; and some of these, according to the account of the Spanish prisoners, contained great riches. This information excited, from time to time, the avarice of speculators, and gave rise to several attempts to procure part of the lost treasure. In the year 1665, a person was so fortunate as to bring up some cannon, which, however, were not sufficient to defray the expenses. Of these attempts, and the kind of diving bell used in them, the reader will find an account in a work printed at Rotterdam in 1669, and entitled "Similari Arx nova et magna gerentur et levitatis." In the year 1680, William Phipps, a native of America, formed a project for searching and unloading a rich Spanish ship sunk on the coast of Hispaniola; and represented his plan in such a plausible manner, that King Charles II. gave him a ship, and furnished him with every thing necessary for the undertaking. He set sail in the year 1683; but being unsuccessful, returned again in great poverty, though with a firm conviction of the possibility of his scheme. By a subscription promoted chiefly by the Duke of Albemarle, the son of the celebrated Monk, Phipps was enabled, in 1687, to try his fortune once more, having previously engaged to divide the profit according to the twenty shares of which the subscription consisted. At first all his labour proved fruitless; but at last, when his patience was almost entirely exhausted, he was so lucky as to bring up, from the depth of six or seven fathoms, so much treasure that he returned to England with the value of two hundred thousand pounds sterling. Of this sum he himself got about fifteen, others say twenty, thousand, and the duke ninety thousand pounds.
After he came back, some persons endeavoured to persuade the king to seize both the ship and the cargo, under a pretence that Phipps, when he solicited for his majesty's permission, had not given accurate information respecting the business. But the king answered, with much greatness of mind, that he knew Phipps to be an honest man, and that he and his friends should share the whole among them had he returned with double the value. His majesty even conferred upon him the honour of knighthood, to show how much he was satisfied with his conduct. We know not the construction of Phipps's apparatus; but of the old figures of a diving machine, that which approaches nearest to the diving bell is in a book on fortification by Lorini; who describes a square box bound round with iron, which is furnished with windows, and has a flood affixed to it for the diver. This ingenious contrivance appears, however, to be older than that Italian; at least he does not pretend to be the inventor of it.
In the year 1617, Francis Kessler gave a description of his water armour, intended also for diving, but which cannot really be used for that purpose. In the year 1671, Witten taught, in a better manner than any of his predecessors, the construction and use of the diving-bell; but he is much mistaken when he says that it was invented at Amsterdam. In 1679 appeared, for the first time, Borelli's well known work de motu animalium, in which he not only described the diving bell, but also proposed another, the impracticability of which was shown by James Bernoulli. When Sturm published his Collegium curiosum in 1678, he proposed some hints for the improvement of this machine, on which remarks were made in the Journal des savants. To him succeeded Dr Halley, whose bell is well known.