4 Adams, On the Mole {Tnlpa eiiropced). 



from memory. I have about loo such plans, and have 

 never found two exactly alike, though naturally they 

 have a certain general resemblance to each other. 



Fig. I. — Plan of tunnels of simple fortress seen from above. 

 a, h. — Tunnels made in excavating nest. 

 c, d.- -Tunnels made for forming protecting heap. 



N.— Nest. 



Fig. 2. — Horizontal view of same. 

 D. — Downshaft. 

 N. — Nest. 



