266 



THE NATURE BOOK 



somewhat higher, which are connectetl 

 by lour or five perpendicular shafts. 

 Runs proceed without at definite inter- 

 \-als from the lower gallery, and there 

 is a single entrance to the nest itself 

 from below. 



In justice to this illustration it should 

 be remembered that the original in- 

 vestigator hardly regarded it as the 



VERTICAL S1':CT10N THKOUGII AN EXCKPTIONALLY LAKGK MOLK- 

 FORTRESS, SHOWING FOUR NESTS /A' SITU. 



The fortress contained six nests in good order and the remains of a seventh. 



sketch-plans of the interiors of about a 

 hundred fortresses, were communicated to 

 the Manchester Philosophical and Literary 

 Societ}' in 1902. 



So far from the galleries surrounding 

 the nest in a Mole-fortress being designed 

 on any definite principle, and serving 

 as an ingenious labyrinth to baffle the 

 Mole's enemies, Mr. Adams holds, as 



the result of 

 four 3'ears' in- 

 vestigations, 

 that no two 

 fortresses are 

 alike, and that 

 the galleries, 

 which assume 

 haphazard 

 curves and 

 tend in hap- 

 hazard direc- 

 tions, " are the 

 natural, inci- 

 dental, and in- 

 evitable outcome 

 of the xvork of 

 excavating the 

 nest-cavity and 

 piling up the 

 superincumbent 

 mound." One 

 could hardly 

 conceive a view 

 more diametri- 

 cally opposed 

 to that pre- 

 N'iously held. 



As to the 

 haphazard d i 



picture of any one fortress in particular, 

 but rather as a type, to which fortresses 

 in general more or less conformed, 

 (ienerations of writers, however, have 

 accepted it without any such reservation, 

 and although many field-workers must 

 have been sadly disillusioned when they 

 applied to the text-book figure the test 

 of practical experience, they seem, with- 

 out exception, to have attributed their dis- 

 illusionment either to personal ill-fortune 

 or to the difficulties inherent in section- 

 ing a honeycombed structure of crumblv 

 material. It was left to Mr. Lionel Adams 

 to ai)i)roach the difficulty in a scientific 

 manner, and his conclusions, based on 



rection of the 

 galleries I am in entire agreement with 

 Mr. Adams. The portion of a Mole- 

 fortress above ground le\'el (the top of 

 the nest is usually about ground level) 

 l^rescnts no definite ]:)lan. and requires 

 no particular engineering skill on the part 

 of the Mole. So far as a simple fortress 

 with one nest in it is concerned, it may 

 well happen that a single spiral gallery, 

 incidental to the work of excavation, 

 may suffice not only to remove the soil_ 

 from the nest-cavity and raise a mound 

 of proportions to the Mole's liking, but 

 also to ensure a stable, well-ventilated, 

 and water-i)roof structure. W'^here the 

 fortress is complicated, however, and 



