VOL. XLVI.] PHILOSOPHICAL TRANSACTIONS. 655 



its placing it in a particular direction; ex. gr. if the lightning struck the needle 

 in the direction of either of the two parallel sides of the lozenge, it must strike 

 the other two sides very obliquely; by which the first two sides may have their 

 polarity destroyed, and a very strong one given them in the contrary direction ; 

 while that of the other sides, if it be inverted, will be very weak; but it is pro- 

 bable that the virtue would be placed obliquely in the direction of the stroke; in 

 either case, these two sides can contribute but very little, if any thing, in direct- 

 ing the card; and if the first two sides only be capable of acting on it, it will 

 point in the direction of those sides, which will produce a variation of about 4 

 points. 



It may further be observed that a needle would not continue long in this state, 

 but would every day grow more and more regular; because if the virtue be placed 

 obliquely, it generally turns itself in the direction of any piece of steel that is 

 long and slender; and that may be the reason why this card is now become regular, 

 except that it is inverted. 



The wires that join the box seem weaker than when first examined; which 

 makes it very probable that they might be vastly stronger when first struck with 

 the lightning; and the same may be likewise true, in regard to the nails in 

 the binacle; which may account for the experiments not answering exactly the 

 same as at first. 



From what has been said it appears, that this form of needles is very improper, 

 and ought to be changed for that of one straight piece of steel ; and then if a 

 needle should be inverted, it might still be used. It also shows the absurdity of , 

 permitting iron of any kind about the compass-box, or the binacle. Whoever 

 considers the whole description here given of this compass, will esteem it a most 

 despicable instrument; how then must any one be shocked to hear, that almost 

 all the compasses, made use of by our trading vessels, are of the same sort! the 

 boxes all joined with iron wire, and the same degree of inaccuracy observed 

 throughout the whole ! 



Of the pretended Serpent-stone called Pietra de Cobra de Cabelos, and of the 

 Pietra de Mombazzu or the Rhinoceros Bezoar, with the Figure of a Rhino- 

 ceros with a double Horn. By Sir Hans Shane, Bart, late Pr. R. S. 

 N°492, p. 118. 



Sir H. S. here communicates to the Society an account of two pretended 

 stones, said to be found in the head of the most venomous snake of the East 

 Indies, called Cobra de Cabelo, with an account of what he has heard, and what 

 he believes they really are. The first he has heard, and believes to be, a stone 

 found in the stomach or intestines of the rhinoceros; not, that he knows, taken 

 notice of by any natural historian, excepting Redi. The place where it is said to 



