Simpler Methods in Crystallography. 421 



tion, unless this is expressly stated in direct connection 

 with the figure. 



Lastly, let me remind the readers of this pamphlet that 

 when an author describes a fossil, his fellow-workers expect 

 him to let them have an opportunity of examining the 

 evidence upon which that description is based. They are 

 apt (and often rightly) to disbelieve him if he asks them to 

 accept a statement without affording them an opportunity of 

 seeing the proof. It should be the same in crystallography. 

 If a writer figures a particular specimen found in a stated 

 locality, under some known set of geognostic conditions, we 

 have a right to expect him to inform us where the original 

 specimen is, just as we have a right to know the whereabouts 

 of a type-specimen of a fossil. If he fail to do that, we are 

 justified in disregarding his statements altogether. 



To return to the subject of drawing crystals. The first 

 point aimed at should be absolute accuracy, adding nothing, 

 omitting nothing, correcting nothing, leaving all the material 

 so that those who come after may judge of the value of the 

 work. 



In the drawings I have made of the crystals in the great 

 Scottish Mineral Collection, which has been under my charge 

 the last twelve years in the Edinburgh Museum of Science 

 and Art, I have acted invariably on this principle. The 

 crystals drawn are clearly indicated by pointers attached to 

 the specimeus when they remain in the matrix, and when 

 they are detached, as many are, they are fastened with 

 seccotine on small corks, which bear the registration number 

 of the crystal figured. These corks, in their turn, are fastened 

 with seccotine on to the cards upon which the drawing is 

 made, and are oriented in the same manner to facilitate 

 reference. 



In the very few cases in which a new or rare form has 

 been supposed to occur, any crystallographer can at once 

 judge for himself whether its claim to rank as new is or is 

 not valid. 



The Orientation oj Drawings of Crystals. — In drawing 

 ciystals, it seems to me that one ought not to be tied to any 



