rum Canonis Descriptio," &c. containing the construction and canon of his logs. rithms, which are those of the kind that is called hyperbolic. This work coming presently to the hands of Mr. Briggs, then Professor of Geometry at Gresham College, in London, he immediately gave it the greatest encouragement, teaching the nature of the logarithms in his pub lic lectures, and at the same time recom mending a change in the scale of them, by which they might be advantageously altered to the kind which he afterwards computed himself, which are thence call ed Briggs' logarithms, and are those now in common use. Mr. Briggs also present ly wrote to Lord Napier upon this pro posed• change, and made journeys to Scotland the two following years, to visit Napier, and consult him about that alter ation, before he set about making it. Briggs, in a letter to Archbishop Usher, March 10th, 1615, writes thus : "Napier, Lord of Marchiston, hath set my head and hands at work with his new and admira ble logarithms. I hope to see him this summer, if it please God; for I never saw a book which pleased me better, and made me more wonder." Briggs accord ingly made him the visit, and. staid a month with him.
The following passage from the life of Lilly, the astrologer, contains a curious account of the meetingof those twoillus trious men. " I will acquaint you (says Lilly) with one memorable story, related unto me by John Marv, an excellent ma thematician and geometrician, whom I conceive you remember. He was ser vant to King James and Charles I. At first, when the Lord Napier, or Merchiston, made public his logarithms, Mr. Briggs, then reader of the astronomy lectures at Gresham College, in London, was so sur prised with admiration of them, that be could have no quietness in himself, until he had seen that noble person, the Lord Merchiston, whose only invention they were : he acquaints John Marr herewith, who went into Scotland before Mr. Briggs, purposely to be there when these two so learned persons should meet. Mr. Briggs appointed a certain day when to meet at Edinburgh ; but failing thereof, the Lord Napier was doubtful he would not come. It happened one day, as John Marr and the Lord Napier were speak ing of Mr. Briggs; ' Ah, John, (said Mer chiston) Mr. Briggs will not now come' At the very instant one knocks at the gate ; John Marr hastened down, and it proved John Briggs, to his great con tentment. He brings Mr. Briggs up into my Lord's chamber, where almost one quarter of an hour was spent, each behold ing the other almost with admiration be fore one word was spoke. At last Mr. Briggs began : ' My Lord, I have under taken this long journey purposely to see your person, and to know by what engine of wit or ingenuity you came first to think of this most excellent help into astrono my, viz. the logarithms ; but, my Lord,
being by you found out, I wonder nobo dy else found it out before, when now known it is so easy.' He was nobly en tertained by the Lord Napier ; and every summer after that, during the Lord's being alive, this venerable man, Mr. Briggs, wentpurposely into Scotland to visit him." Napier made also considerable im provements in spherical trigonometry, &c. particularly by his " Catholic, or Universal Rule," being a general theo rem by which he resolves all the cases of right-angled spherical triangles in a man ner very simple, and easily to be remem bered; namely, by what he calls the five circular parts. His construction of loga rithms too, beside the labour of them, manifests the greatest ingenuity. Kep ler dedicated his "Ephemerides" to Napier, which were published in the year 1617 ; and it appears from many passages in his letter, about this time, that he accounted Napier to be the greatest man of his ace, in the particu lar department to which he applied his abilities.
The last literary exertion of this emi nent person, was the publication of his " Rabdology and Promptuary," in the year 1617, soon after which he died at Merchiston, the 3d of April, in the same year, in the sixty-eighth year of his age. The list of his works is as follows : 1. A Plain. Discovery of the Revelation of St. John ; 1593.
2. Logarithmorum Canonis Descriptio; 1614.
3. Mirifici Logarithmorum Canonis Constructio ; et eorum ad Naturales ipso rum numeros habitudines; una cum ap pendice, de alia eaque prastantiore Lo garithmorum specie, condenda. Quibus accessere propositiones ad triangula sp hs rice faciliore calculo resolvenda. Una cum Annotationibus aliquot doctissimi D. Henrici Briggii in eas, et memoratam ap pendicem. Published by the Author's son, 1619.
4. Rabdologia, seu Numerationis per Virgules, libri duo ; 1617. This contains the description and use of the bones or rods ; with several other short and inge. nious modes of calculation.
5. His Letter to Anthony Bacon, (the original of which is in the Archbishop's Library at Lambeth), entitled Secret In ventions, profitable and necessary in these days for the defence of this island, and withstanding strangers, enemies to God's truth and religion ; dated June 2, 1596.
Nerve's rods, or bones, an instrument invented by the above-named person, whereby the multiplication and divi sion of large numbers are much facili tated.