newness of the arguments they may offend or trouble young students in the art, we therefore (by true knowledge of the wise) do attribute the middle seat of the world to the earth, and appoint it the centre of the whole."

ENGLISH SCIENCE IN THE SEVENTEENTH CENTURY.

BACON.-NAPIER.

But the daylight that had already arisen on the continent of Europe was soon to visit our island. The next age, in which Galileo, and Kepler, and Descartes, and Torricelli, and Pascal, and Huygens, revolutionised the entire structure and character of the mathematical and mathematico-physical sciences abroad, was ushered in among us by the bold speculations of Bacon and the brilliant inventions of Napier. Of what has been called the Baconian philosophy, and the amount of the effect it may be supposed to have had in impelling and directing the progress of science, we have already spoken. The writings of Bacon probably did more service by exciting and diffusing the spirit of scientific observation and research, than by any new light they afforded for its guidance, which in truth was no more than it must have furnished to itself as soon as it was fairly awakened and engaged in operating. At all events, neither the pure sciences of figure and number, nor even those of the mixed sciences that have been chiefly advanced by the aid of mathematics and calculation, among which are astronomy, mechanics, and all the principal branches of what is commonly called natural philosophy, can well have received either impulse or direction from Bacon, who was not only entirely unacquainted with geometry

and algebra, but evidently insensible even of their value or their use. Of those mathematical and analytical investigations which are the chief glory of the science of the seventeenth and eighteenth centuries, there is not the slightest anticipation in Bacon, nor any direction or suggestion by which they could have been at all promoted. Napier's great invention of logarithms, on the contrary, has from his own day to the present hour been one of the most active and efficient servants of all the sciences dependent upon calculation; nor could those of them in which the most splendid triumphs have been achieved have possibly been carried to the height they have reached without its assistance. The Mirifici Logarithmorum Canonis Descriptio was published by Napier at Edinburgh in a small quarto volume in the year 1614; and logarithms received their improved form, or that in which we now possess them, from their inventor and his friend Henry Briggs, in the same or the following year, although they were not partially published in that form till 1618, after the death of Napier, by Briggs, by whom the calculations had been performed.

Many inventions," says a late distinguished historian of science, "have been eclipsed or obscured by new discoveries, or they have been so altered by subsequent improvements that their original form can hardly be recognised, and, in some instances, has been entirely forgotten. This has almost always happened to the discoveries made at an early period in the progress of science, and before their principles were fully unfolded. It has been quite otherwise with the invention of logarithms, which came out of the hands of the author so perfect that it has never yet received but one material improvement

-that which it derived, as has just been said, from the ingenuity of his friend in conjunction with his own. Subsequent improvements in science, instead of offering anything that could supplant this invention, have only enlarged the circle to which its utility extended. Logarithms have been applied to numberless purposes which were not thought of at the time of their first construction. Even the sagacity of the author did not see the immense fertility of the principle he had discovered: he calculated his tables merely to facilitate arithmetical, and chiefly trigonometrical computation; and little imagined that he was at the same time constructing a scale whereon to measure the density of the strata of the atmosphere and the heights of mountains, that he was actually computing the areas and the lengths of innumerable curves, and was preparing for a calculus which was yet to be discovered many of the most refined and most valuable of its resources. Of Napier, therefore, if of any man, it may safely be pronounced, that his name will never be eclipsed by any one more conspicuous, or his invention be superseded by anything more valuable.”* In the same volume with his logarithms Napier gave to the world the two very elegant and useful trigonometrical theorems known by his name.

OTHER ENGLISH MATHEMATICIANS OF THE EARLIER PARTI OF THE SEVENTEENTH CENTURY.

Of the other English mathematicians of this age, Harriot, Briggs, and Horrocks may be mentioned as the most famous. Thomas Harriot, who died in 1621, is the

Playfair's 'Dissertation on the Progress of Mechanical and Physical Science (in Encyclopædia Britannica), p. 448.*

author of a work on algebra (Artis Analyticæ Praxis), not published till ten years after his death, which makes an epoch in the history of that science, explaining in their full extent certain views first partially propounded by Vieta, and greatly simplifying some of the operations. To Harriot we also owe the convenient improvement of the substitution of the small for the capital letters which had been used up to this time. It appears, too, from his unpublished papers preserved at Petworth (formerly the seat of his patron the Earl of Northumberland), that he is entitled to a high place among the astronomers of his day, having, among other things, discovered the solar spots before any announcement of them was made by Galileo, and observed the satellites of Jupiter within a very few days after Galileo had first seen them.* Henry Briggs, besides the share he had, as mentioned above, in the improvement of logarithms, is entitled to the honour of having made a first step towards what is called the binomial theorem in algebra, finally discovered by Newton.

He died in 1630. His Trigonometria Britannica, or tables of the logarithms of sines, &c. (in the preface to which is his distant view of the binomial theorem), was published in 1633, by his friend Henry Gellibrand, who had been for some time associated with him in the calculation of the logarithms. Samuel Horrocks, or Horrox, a native of Toxteth, near Liverpool, was an astronomer of remarkable genius, who died in 1641, at the early age of twenty-two. He was the first person who saw the planet Venus on the body of the sun: his

*These facts, ascertained from the examination of Harriot's papers, then in possession of the Earl of Egremont, were first stated by Zach in the Astronomical Ephemeris of the Berlin Royal Society of Sciences for 1788.

account of this observation (made 24th November, 1639) was printed by Hevelius at the end of his Mercurius in Sole Visus, published at Dantzig in 1662. But Horrocks is principally famous in the history of astronomy as having anticipated, hypothetically, the view of the lunar motions which Newton afterwards showed to be a necessary consequence of the theory of gravitation. This discovery was given to the world by Dr. Wallis, in a collection of Horrocks's posthumous papers which he published at London in 1672. It had been originally communicated by Horrocks in a letter (which has also been preserved, and is to be found in some copies of Wallis's publication) to his friend William Crabtree, whose fate, as well as genius, was singularly similar to his own. Crabtree was a clothier at Broughton, near Manchester, and had made many valuable astronomical observations (a portion of which have been preserved and printed) when he was cut off only a few months after his friend Horrocks, and about the same early age. Another member of this remarkable cluster of friends, whom a common devotion to science united at a time when the fiercest political heats were occupying and distracting most of their countrymen, was William Gascoigne, of Middleton, in Yorkshire, who also died very young, having been `killed, about two years after the decease of Horrocks and Crabtree, fighting on the royalist side, at the battle of Marston Moor. He appears to have first used two convex glasses in the telescope, and to have been the original inventor of the wire micrometer and of its application to the telescope, and also of the application of the telescope to the quadrant. A fourth of these associated cultivators of science in the north of