126 The Ottawa Naturalist. 



Now with regard to the second law : 



the law of whole numbers. The meaning of this is simply 

 that Haiiy found that the secondary faces had only such positions as 

 would result from the omission of whole numbers of rows of bricks 

 and from the layers having a thickness measured by some multiple 

 of that of a single brick. He actually proved by measurements that 

 the number of bricks in the width or height of a step rarely exceeds six 

 But Hauy's theory of the structure of crystals had many weak 

 points in it which speedily became objects of attack. 

 One of his first critics was Weiss, Professor of Mineralogy at 

 Berlin, who translated Hauy's work into German, in 1S04. 



He shewed that Hauy's " primitive forms," as professor Nichol puts 

 it, "erred both in excess and defect," and that the " bricks" were not 

 needed at all to explain the facts observed, in fact, the planes, so-called, 

 built up of them, would not reflect light. 



Bernhardi, a doctor residing in Erfurt, pointed out that the 

 dimensions of the " primitive forms " could not be determined from 

 themselves, their height depending on another form. Also that various 

 crystals, which he named, were much more readily explained from other 

 forms than those taken by Haiiy as their " primitives ". In fact, 

 numberless objections were raised ; thus, it by no means follows that 

 because a crystal miy be reduced to a certain form by cleavage, that its 

 growth has resulted from the grouping together of fragments having that 

 form ; again, some minerals have no cleavage, whilst others cleave only 

 in one or two directions; again, it is hard to conceive of a crystal built 

 up, for instance, of little octahedrons, which, in order to have their 

 faces parallel to the cleavages of the resulting crystal, and be parallel to 

 each other, would have only their angular points in contact, thus form- 

 ing a most skeleton-like and unstable structure. 



But Hauy's theory, pointing as it did to the great importance of the 

 angles of the faces and cleavages of crystals, served to direct attention 

 to them, and led to their more accurate study and determination. 



It was not so much Hauy's data that required correction, but the 

 substitution of a better theory to connect his facts was needed. 



The development of the atomic theory of the constitution of 



