He hath invented an engine for the speedie working of division, etc., or for the speedie and immediate finding out the divisor.
An instrument for the Emperor of Germany, 1692/3.
[1725]The first thing he published was—An attempt for the explication of the phaenomena observeable in the XXXV experiment of the honourable Robert Boyle, esq., touching the aire: printed for Sam. Thomson at the Bishop's head in Paule's churchyard, 1661, 8vo: not now to be bought, and, though no bigger then an almanack, is a most ingeniose piece.
The next moneth he published another little 4to pamphlet,—Discourse of a new instrument he haz invented to make more accurate observations in astronomy then ever was[1726] yet made, or could be made by any instruments hitherto invented, and this instrument (10 or 12 li. price) performes more, and more exact, then all the chargeable apparatus of the noble Tycho Brache or the present Hevelius of Dantzick.
<In MS. Aubr. 6, fol. 30, 31, is this letter from Aubrey to Anthony Wood, enclosing a communication from Hooke.>
September 15, 1689.
Mr. Wood!
Mr. Robert Hooke, R.S.S. did in anno 1670, write a discourse, called, 'An Attempt to prove the motion of the Earth,' which he then read to the Royal Society; but printed it in the beginning of the yeare 1674, a strena[1727] to Sir John Cutler to whom it is dedicated, wherein he haz delivered the theorie of explaining the coelestial motions mechanically; his words are these, pag. 27, 28. viz.:—
['In[1728]the Attempt to prove the motion of the earth, etc., printed 1674, but read to the Royall Society, 1671: pag. 27, line 31—
'I shall only for the present hint that I have in some of my foregoing observations discovered some new motions even in the Earth it self, which perhaps were not dreamt of before, which I shall hereafter more at large describe, when further tryalls have more fully confirmed and compleated these beginnings. At which time also I shall explaine a systeme of the world, differing in many particulars from any yet known, answering in all things to the common rules of mechanicall motions. This depends upon 3 suppositions; first, that all coelestiall bodys whatsoever have an attractive or gravitating power towards their own centers, whereby they attract not only their own parts, and keep them from flying from them, as we may observe the Earth to doe, but that they doe also attract all the other coelestial bodys that are within the sphere of their activity, and consequently that not only the Sun and the Moon have an influence upon the body and motion of the Earth, and the Earth upon them, but that Mercury also, Venus, Mars, Saturne, and Jupiter, by their attractive powers have a considerable influence upon its motion, as, in the same manner, the corresponding attractive power of the Earth hath a considerable influence upon every one of their motions also. The second supposition is this, that all bodys whatsoever, that are putt into direct and simple motion will soe continue to move forwards in a straight line, till they are by some other effectuall powers deflected and bent into a motion describing a circle, ellipsis, or some other uncompounded curve line. The third supposition is, that these attractive powers are soe much the more powerfull in operating, by how much nearer the body wrought upon is to their own centers. Now what these severall degrees are, I have not yet experimentally verified.'—But these degrees and proportions of the power of attraction in the celestiall bodys and motions, were communicated to Mr. Newton by R. Hooke, in the yeare 1678, by letters, as will plainely appear both by the coppys of the said letters, and the letters of Mr. Newton in answer to them, which are both in the custody of the said R. H., both which also were read before the Royall Society at their publique meeting, as appears by the Journall book of the said Society.—'But it is a notion which if fully prosecuted, as it ought to be, will mightily assist the astronomer to reduce all the coelestiall motions to a certaine rule, which I doubt will never be done true without it. He that understands the natures of the circular pendulum and circular motion, will easily understand the whole ground of this principle, and will know where to find direction in nature for the true stating thereof. This I only hint at present to such as have ability and opportunity of prosecuting this inquiry, and are not wanting of industry for observing and calculating, wishing heartily such may be found, having my self many other things in hand, which I will first compleat, and therefore cannot soe well attend (to) it. But this I durst promise the undertaker; that he will find all the great motions of the world to be influenced by this principle, and that the true understanding thereof will be the true perfection of Astronomy.']