CONTENTS AND ARGUMENT. 



Preface, ........ 1 



In this is stated the exigence existing in the Cape of Good Hope, and by inference 

 existing elsewhere, for the adoption of measures similar to what have been 

 adopted in France to avert the destructive effects of floods and inundations 

 (p. 1). 



Inteoduction, . ..... 7 



The application of the terms reboisement and gazormement is stated ; illustrations 

 of the evils which the operations so designated have been employed to remedy 

 are given in citations descriptive of Devoluy and other places in the High 

 Alps (p. 7) ; and in further illustration of the same there are cited cor- 

 responding cases from Abyssinia, India, Switzerland, and Italy (p. 11) ; an 

 account is given of the fcehn, the wind occasioning the torrents of the Alps 

 (p. 13). 



PART I. — RisuMi OF Sueell's Study of Alpine Toeeents, . 15 



States the position assigned to Surell'swork (p, 15). 



Section I. — The Phenomena of Alpine Torrents, . . .15 



Gives the distinguishing characteristics of rivers, of torrential rivers, of torrents, 

 and of mountain streams ; of different classes of torrents, of glacier torrynts, 

 and of torrents hlanc (p. 15) ; detailed information is given in regard to the 

 beds of torrents, and the continuation of these in the ravines of the mountains, 

 and in regard to the thalweg or inclination of the valleys, andto the operation of 

 flowing water in the formation of these (p. 17) ; in regard to Bassins de re- 

 ception, or basins drained by torrents (p. 21); to Can£Lux_aecoulement^ or water- 

 courses ; to Lits de deieetion, or beds of deposit (p. 23) ; and in regard to 

 torrential fleods of water ; to the occasion of these, and to the avalanche-like 

 effects produced by them (p. 25). 



Section II. — Natural History of Alpine Torrents, . . .30 



It is stated that there may be seen in the Alps old beds of torrential deposit 

 covered with vegetation of many years growth, \Thich proves that the torrtnt-j 

 forming them have long ceased to flow ; and that such may be seen in various 

 stages of advancement, indicating different periods of extinction of torrents of 

 a former day (p. 30) ; that in view of these and other facts observed, the his- 

 tory of a torrent may be considered as marked by three periods — that of the 

 creation of the curve of the bed, that of the deepening and enlarging of this, bat 

 with the course inconstant, and that with this stable and fixed,— followed in the 

 cases referred to by the extinction of the torrent (p. 33) ; that many torrents 

 have originated from mountains, or mountain sides, having bei n denuded 

 by the clearing away of forests ; and that they have owed their development 

 to the combined operation of deluges of rain (p. 34), the nature of the soil, and 

 the consequent contour of the country(p. 36)— the latter an effect as really as a 

 cause of the flood (p. 38). 



Section III. — Remedial Appliances to prevent the destructive conse- 

 quences of Torrents, . . . . . .41 



What were sought to be prevented were inundations, the washing away of lands, 

 and the ruin of fertile fields by the deposit on them of the detritus washed 

 away (p. 41). Embankments were employed to prevent inundations, but 

 irithout success (p. 44.) The other evils were not less serious, of which illus- 



