Extracts of Two Letters, Written to the Publisher from Hamborough by the Learned Christophorus Sandius, Concerning the Origin of Pearls

Extracts of two Letters, written to the Publisher from Hamborough by the Learned Christophorus Sandius, concerning the Origin of Pearls. The first is of Decemb. 15. 1673. thus English't; Touching the Origin of Pearls, of which I formerly gave an intimation, be pleased to receive this account. The Pearl-shells in Norway and elsewhere do breed in Sweetwaters. Their shells are like to those, which commonly are called Mussels, but they are larger. The fish in them looks like an Oyster, and it produceth a great cluster of Eggs, like those of cra-fishes, some white, some black (which latter yet will become white, the outer black coat being taken off;) These Eggs, when ripe, are cast out, and being cast out they grow, and become like those that cast them. But sometimes it happens, that one or two of those Eggs stick fast to the sides of the matrix, and are not voided with the rest. These are fed by the Oyster against her will, and they do grow, according to the length of time, into pearls of different bignesses, and imprint a mark both in the fish and shell, by the situation conform to its figure. So far the first Letter; The matter of which being new, but destitute of proof, the Publisher took the liberty of desiring from the Author the favour of imparting to him what ground he had for this assertion: Whereupon was returned this second Letter, dated Febr. 27. 1674; viz. As to the authority, I have to assert such an origin of Pearls, as I have done in my former; I here declare, that a certain Dane, called Henricus Arnoldi, an ingenuous and veracious person, having by his own Experience found it so at Christiana in Norway, did in that manner relate it to me, as I imparted it to you, he having with great seriousness assured me of the truth thereof. Besides, the thing seems highly probable, neither do any considerable objections appear against it. If I should chance to go into those parts, or at least into the Country of the Dukes of Brunswick, where also Pearls are found not inferior to the oriental ones of the same size, I should not fail to endeavour to make the observation myself. An Accompt of some Books. I. An Attempt to prove the MOTION of the EARTH from Observations; made by Robert Hook Fellow of the R. Society. London in 4° printed for J. Martyn at the Bell in St. Pauls Church-yard, 1674. The ingenious Author of this Attempt, having consider'd with himself, that the grand Controversie about the Motion of the Earth remains yet undetermin'd, and finding, there was no other means left for human Industry to decide it but by observing, whether there be any sensible Parallax of the Earth's Orb amongst the Fixt Stars; did thereupon resolve to employ himself in making some Observations concerning so important a point in Astronomy. And, after he had examined the ways and instruments for all manner of Astronomical Observations, hitherto made use of, and consider'd of the inconveniences and imperfections of them; and having also duly weighed the great accurateness and certainty, that this Observation of the Earth Parallax required: He next contrived a way of making Observations, that might be free from all the former inconveniences and exceptions, and, as near as might be, fortified against any other that might be invented or raised against it. This way he gives an Account of in this present Tract, which is; To observe by the passing of some considerable Star near the Zenith of some place, whether such a Star doth not at one time of the year pass nearer to that Zenith, and another, farther from it; thus reasoning with himself, That, if the Earth doth move in an Orb about the Sun, and that this Orb hath any sensible Parallax amongst the Fixt Stars, this must necessarily happen, especially to those Fixt Stars, which are nearest the Pole of the Ecliptique. Accordingly he affirms to have actually made four Observations, in this Tract described; by which, he saith, 'tis manifest, that there is a sensible Parallax of the Earth's Orb to the Fixt Star in the Dragons head, and consequently a Confirmation of the