280 NATURAL SCIENCE [October 



slate and that of the same material when disintegrated and wet, is 

 shown by the fact that the former will stand at an angle of 37°, while 

 the angle of rest of the latter is not more than 16°, and the author 

 points out that " the maximum angle of safety of interbedded rocks is 

 determined by that of the weakest constituent." 



The author devotes a few pages to the classification of the land- 

 slips according to Heim's scheme, and proceeds to describe the warn- 

 ings which foreshadow a landslip, such as the opening of cracks 

 parallel to the strike of the beds and changes in the courses of streams. 

 Besides landslips of the ordinary type there occur subsidences caused 

 l>y the removal in solution of the dolomitic cement of the sandstones 

 and the consequent settling down of the loose material. 



The most efficient methods of preventing the landslips appear to 

 be the provision of means for the removal of the rain-water before it 

 can percolate into the ground, and also for the discharge of subter- 

 ranean water by the construction of adits. 



The Report concludes with a detailed description of three particular 

 sites, whose characters illustrate the results of the various forces- 

 described by the author. The value of the work is increased by the 

 well-drawn diagrams and sections, and by the excellent map for which 

 a special survey was made ; but it may be worth while to ask whether 

 such terms as ' demi-official ' and the contraction ' para ' for paragraph 

 are improvements on the conventional modes of expression. 



Investigations into Applied Nature. By William Wilson, Junior. 8vo, pp. viii., 

 143. London: Simpkin, Marshall & Co., 1896. 



This little book hardly calls for serious review. The author may be 

 a pleasant enough companion in a country walk, if one were willing 

 to be a little bored, and may also have certain powers of observation, 

 but he is unable to arrange his matter in book-form or to express him- 

 self in English. The book is a strange conglomeration. The first few 

 chapters relate to " Our Indigenous Flora as Food-Plants " ; " On the 

 Habits and Instinct of the Rook " ; " Our Birds and their Functions " ; 

 " The Potato Disease"; and so on. The first paper has already been 

 inflicted upon the British Association, another on the Inverness Scien- 

 tific Society, and another on the Keith Literary Institute. Of pasture 

 plants Mr Wilson says, "We have not as much in general use, taking 

 the knowledge of variety as known to the average agriculturist into 

 account, as we can scarcely say there is any variety in them." And 

 speaking of the winter food of animals, " We find that human in- 

 genuity has invented a large number of so-called spices or condiments 

 to assist in feeding and keeping them (besides the fields' produce, 

 turnips and straw), and are generally used." The funniest chapter is 

 that on the crow, which, " like most objects of natural history, is very 

 imperfectly understood." It seems to be a selfish and quarrelsome 

 bird, but wily withal ; " unusual operations on the part of man on the 

 top of a stack is watched by the rook with suspicion, and in nine cases 

 out of ten that stack will be avoided by them." "Atmospheric 

 changes produce a very marked effect on them. There is no doubt 

 but this causes the peculiar reeling in the atmosphere [!]. Before 

 rainfall a dulness passes over them, early brightening up after the 



