2^ Commander Pearse on the Formation of Anchors. 



by heat, and without any regular arrangement of its particles, 

 will in process of time gradually change its character, and con- 

 vert itself into regular crystals, possessing a mathematical re- 

 gularity of structure, and displaying all the wonderful pheno- 

 mena of double refraction. A mineral body will, in the course 

 of time, part with some of its ingredients, or take in others, 

 till it has become a new mineral, and has entirely lost its per- 

 sonal identity ; — and (what has recently been discovered by a 

 foreign member of this Society,) a regular crystal may, by the 

 mere introduction of heat, have the whole arrangement of its 

 molecules converted into an opposite arrangement, developing 

 new physical properties which it did not before possess. In 

 these changes the molecules must have turned round their axes, 

 and taken up new positions within the solid, while its external 

 form has suffered no apparent change, and while its general 

 properties of solidity and transparency have remained unalter- 

 ed. Before another century passes away, the laws of such 

 movements will probably be determined ; and when the mole- 

 cular world shall thus have surrendered her strongholds, we 

 may look for a new extension of the power of man over the 

 products of inorganic nature. 



Ai.iu:EiiJ.Y, December ]3, 1828. 



Art. VI. — Remar'ks on the formation of Anchors. By Com- 

 mander John Pearse, R. N. Communicated by the 

 Author. 



It does not appear that the formation of anchors has been very 

 generally viewed by seamen on such principles as would enable 

 them to form a just conclusion of that best adapted for the 

 safety of a ship. Very old seamen argue in favour of a long 

 shanked anchor, without being able to offer anything satisfac- 

 tory in support of it ; and such an opinion is no doubt gene- 

 rally formed from custom or prejudice. I shall therefore en- 

 deavour to illustrate, on mathematical principles, what appears 

 to be the advantages of a short shank. 



Figures 4th and 5th of Plate II. are intended to represent 



