Diamond with Theoretical Carbon Atoms. 259 



of the axes represented by the crosses to indicate the tails of 

 the arrows points downward perpendicular to the plane of the 

 paper. Designating this plane of atoms, bounded by the full 

 marginal lines, as plane number — 1, the plane of atoms next 



Fier. 2. 



i 

 I 

 I 

 I 



! 

 I 

 I 

 I 

 I 

 J 

 I 

 I 

 I 

 I 

 I 

 I 

 I 

 I 

 I 



!_ 



above this at a vertical distance ^^fbl will contain th e 



point and all similar centres of tctrahedra, and may be 

 numbered plane zero. If the plane No. —1, bounded by the 

 full lines, is moved, carrying the atoms with it, into the 

 position indicated by the lines of dashes, the upper and lower 

 boundaries^ remaining in the same position, this will be the 

 correct position for all atoms and axes in plane No. zero, and 

 the atom taking the position will point downward perpen- 

 dicular to the paper. The next plane of atoms may be called 



phine No. +1, at a vertical distance t\/6Z above No. zero. 



This coincides in all respects with plane zero if brought into 

 coincidence by moving perpendicular to the paper. The 



plane No. + 2 above No. + 1 is at short interval —^ ^/bV, 



and is represented in its proper relation to plane No. —1 by 

 moving the full line area into coincidence with the line of 

 dots, so that the atom in plane zero is directly under the 

 centre of a triangle where the arrows point away from its 



centre. Plane +3 is at a long interval - \/6l above +2 



S 2 



1 



\ 



/ 



V 





y 





X 



/ 



x! 



1-** 



X 



-a* 



X 



-** 





X 





-♦* 



X J -~ 



y J v 



y 



X 



y 





\ 





* 



\ 



S\ 



|X 



-*» 



X 



-*« 



X 





-*» 





X 



- X 



v : / 



\ 



y 



\ 





/ 





X 



y 



vl 



i** 



X 



-*♦ 



X 



-c 





V 





_»* 



* r 



y ! \ 



y 



\ 



y 





x 





y 



X 



1* 



-** 



X 



-** 



X 





-tr+ 





X 



~ 1 x 



x t / 



V 



y 



\ 





y 





x 



y 



VI 



'-*» 



X 



-€* 



X 



-o-» 





X 





-•* 



X ' — 



y ! v 



y 



V 



/ 





x 





y 



x 



A 



IX 



-»* 



X 



^o 



X 





-0+ 





X 



— I X 



> ' y 



V 



y 



X 





y 





\ 



y 



V 



\** 



X 



■*• 



X 



-w 





X 





-*+ 



*r 



y ! v 



y 



V 



y 





x 





y 



x 



l x 



-♦* 



X 



-•» 



X 





-•-» 





X 



-~ 1 x 



> ^ y 



V 



y 



x 





y 





\ 



y 



■ I- 





X 



-++ 



X 



-+-■; 





X 





-♦* 



* r v 



y 



V 



y 





x 





y 



x 



-1- 



X 



-•* 



X 



-•* 



X 





-♦* 





X 



\ . y 



V 



y 



x 





y 





V 



^ y 



X ^ 



y i" v 



X 



y 



> 



X 



y 





x 





y 



V 



r 



:* 



-0-» 



X 



-•* 



X 





-♦-t 





X 



- 1 * 



