Though much hath been already said and written of _Petrification_, yet 'tis conceived, that all that comes so far short of a competent stock for the composing of a perfect _History of Petrification_, that the incompleatness thereof ought to awaken the more diligent attention of the Curious, and to call in their aid for Additions, thereby so to encrease and to complete the _Materials_ for that work, that it may the better serve to clear and make out the Cause of that Transmutation. And that the rather, because if it lay in the power of humane Skill (by the knowledge of _Nature_'s works) to raise _Petrification_, or to allay, or prevent it, or to order and direct it (which perchance in time might be attained the said way) much use might be made of this Art; especially if it could be made applicable to hinder the Generation of the Stone and Gravel in humane Bodies, or to dissolve the Stone, where 'tis formed; besides other valuable Uses, that might be excogitated. Upon this Consideration, care is, and further _will be_ taken in these Papers, to record, among other Observables of Nature, what shall be communicated of this kind of _Change_. In _Num._ 1. 2. and 5. several Relations have been made belonging to this Argument. Much of it, together with considerable Reflections may be seen in Mr. _Boyle_'s _Essay of Firmness_: In _Helmont de Lithiase_, where, among other remarques, is recited the Testimony of _Paraeus_ of a _Petrified Child_ seen at _Paris_, and by the Owner used for a _Whetstone_: In _Densingius_'s Historia _Infantis in Abdomine inventi, & in duritiem lapideam conversi_: In Mr. _Hook_'s _Micrography_, and in others. To omit now, what has been related (but perhaps not well enough attested) by Authors, concerning the stupendious Petrifications of whole Companies of Men, and Troops of Cattle; by _Aventinus_, lib. 7. _Annal. Bojorum_; by _Purchas_ in his _Pilgrimage_ p. 416. in fol. printed at _London_ 1614, and, (of a Troop of _Spanish_ Horsemen) by _Jos. Acosta_ lib. 3. c. 9.