CRYSTALLOGRAPHY MINERALOGY. 



THE history of Crystallography, like that of many other of the 

 sciences called inductive, commences almost within the last 

 hundred years. It is the record of the gradual but vigorous 

 growth of a science that shares with Astronomy the privilege of 

 having explained a complicated series of natural phenomena by 

 deducing them from one simple geometrical law. As the character 

 of the motions of celestial bodies is deduced from the law of 

 gravitation, so may that of the polyhedral forms which crystals can 

 assume be anticipated when the rationality of the anharmonic 

 ratios of four tautozonal planes has been asserted as the law of 

 their construction. It will here be only necessary to trace the 

 steps by which this, and the principles of symmetry, physical, 

 as well as morphological, involved in it, came to be esta- 

 blished, so far as may serve to show the progressive demand for 

 new and more exact implements for investigation in crystallo- 

 graphic research. 



The attempts of Pliny to describe the form of crystallus (quartz) 

 and of the adamas, leave us without the power of saying what 

 the latter, at least, of these minerals was. In the great six- 

 teenth century, indeed, the idea of attaching significance to the 

 mutual inclination of the faces of crystals first takes shape in the 

 pages of Gesner. But though De la Hire had, early in the 

 seventeenth century, made measurements of crystals, the true 

 father of Crystallography was Rome de Lisle; he first made 



