A new system of Crystallographic Symbols. 255 
yet by half only of the usual number of planes. Other instances 
will be found in Fig. 2, which will be noticed in the remarks on that 
figure. 
As a recapitulation the following table is introduced, showing the 
letters that are to be applied to the angles and edges of the several 
prisms. 
1 Cube. Lat. sol. angle a 
Planes* P || 6 Rhombohedron. 
Edges e Planes i 
Angles a Superior edges e 
2 Rt. sq. Prism. ‘ Lateral edges € 
Lateral planes P Dominant sol. angle a 
Lateral edges e ateraly oy: i a 
Basal e 7 Ob. rbc. Prism. 
Angles Py Lat. planes P 
3 Rt. rect. Prism. Front lat. edge e 
Rt. lat. plane Pp’ Front sup. bas. edges e 
pres Ce 1 Side lat. edge e 
Lat. edges e Front inf. bas. edges e 
Rt. basal edge é Front sup. sol. angle 
Di Salis ee e (dominant) a 
Angles a Front inf.“ ccm 
4 Rt. rbc. Prism. Wats sup.) ae Som iy 
Lat. planes P 8 Ob. rbdl. Prism. 
Front lat. edge (obtuse) e Rt. lat. plane i? 
Basal edges e Lt. lat. plane P 
Side lat. edge (acute) e Front lat. edge e 
Front solid angle a Rt. sup. bas. edge é 
Lat. (4 66 a Lit. 66 66 66 e 
5. Rt. rbdl. Prism. Side lat. edge e 
Rt. lat. plane (smallest) P’ Rt. inf. bas. edge é 
| Dire OG P' Lt. “ “ « cE 
Front lat. edge (obtuse) e Front sup. sol. angle a 
Rt. bas. edge € LNiRoae yah | OO 5 Ge a 
lia e Rt. lat. sup. < a 
Side lat. edge (acute) e Li sna a 
Front sol. angle a 
* If it is ever found necessary to distinguish these planes, the dashes may be ap- 
plied to the lateral faces according to the rules already given. 
