6o8 



NA TURE 



[April 30. 190^ 



population during the last few years. It is antici- 

 pated that at the end of the next half century there 

 will be 200 million people to feed. It has for some 

 time past been recognised that the arid regions of the 

 West, at the foot of the Rocky Mountains, consisting 

 of enormous areas of barren sands broken only by 

 patches of yuccas and sage bushes, becomes, if irri- 

 gated, capable of growing crops of all kinds and in 

 the greatest luxuriance. Already where irrigation has 

 been applied, the traveller almost suddenly passes from 

 a desolate and an apparently worthless region to a 

 land of plenty, and is confronted by orchards and 

 gardens which resemble the century old creations of 

 France and Italy, with homes rivalling in taste and 

 convenience those of the eastern States. The climate, 

 though arid, is remarkably healthy, the heat of the 

 southern summers and the cold of the northern winters 

 being mitigated by the dryness of the atmosphere. 

 The mountains and valleys of this district are recog- 

 nised as natural sanitaria, to which thousands of per- 

 sons resort in order to live. The arid land, when irri- 

 gated, is capable of producing crops worth 20/. an acre. 

 Oranges and grapes grow and ripen abundantly, and 

 in Southern California an orange grove of twenty 

 acres constitutes an estate. 



The value of the land for raising crops when irri- 

 gated became first recognised bv the flourishing con- 

 dition of the colony established by Horace Greek in 

 Colorado, and after his success numerous irrigation 

 schemes were set on foot, both by single settlers and 

 companies. The first step in the change from sage 

 bush desert to fields of grain is the construction of a 

 ditch by the small holder, or of a canal which shall 

 be large enough to water several farms. These canals, 

 in some cases, are large enough to supply from five 

 hundred to a thousand eighty acre farms. The water 

 is supplied to the farmers in fixed quantities, measured 

 either by the miner's inch or the cubic foot, being the 

 volume of water that will flow through an inch or foot 

 square orifice under a designated pressure ; or else by 

 the acre foot, being the quantity required to cover an 

 acre to a depth of one foot. The price paid for the 

 water varies according to the locality and the cost of 

 the works. 



When the rivers and streams carried a surplus, water 

 was diverted with lavish prodigality, and irrigators 

 gave scant heed to their respective rights because, so 

 long as each had all he needed, he was satisfied. 

 When, however, irrigated agriculture became an 

 assured success, and the area of the irrigated farms 

 increased, innumerable quarrels and law suits as to 

 water rights ensued, and as, according to the author's 

 estimate, there is only a sufficient supply of water to 

 irrigate one-tenth of the arid West, the right to obtain 

 this will be guarded with greater jealousy as time goes 

 on. The laws in the different States as to these rights 

 vary considerably, and are set out with much detail bv 

 the author. This, together with the practical inform- 

 ation given as to irrigation, will render this book of 

 very great service to those engaged either as settlers 

 on the irrigated lands or to hydraulic engineers 

 engaged in laying out irrigation works. 

 NO. I748, VOL. 67] 



OUR BOOK SHELF. 



Algebra, Part i. By Kaliprasanna Chottoraj. Pp. 



vi + 482. (Calcutta: The City Book Society, 1903.) 

 This book is "an elementary treatise on algebra in- 

 tended for use in Indian high schools." " Each rule 

 and each process are followed by a well-graduated 

 and sufficiently large collection of examples." These 

 quotations from the preface serve to characterise the 

 book. It is intended for beginners, and includes the 

 theory of indices, and proportion, but not quadratic- 

 equations. The book is too full of rules and processes, 

 and the student is in danger of losing his grasp of tne 

 fundamental ideas through the bewildering number of 

 special methods, and may be led to think that he must 

 remember the many rules and artifices which can only 

 be acquired by practice and experience. Thus, for 

 instance, under the heading of the resolution of 

 x'+ax + b into factors, we find a first method, a second 

 method, followed by two important hints and forty- 

 live examples; then ax 2 + bx + c is treated on the same 

 lines and at the same length. 



The explanations of fundamental principles are 

 sound and clear, and seem designed to meet everv con- 

 ceivable difficulty, but there is a tendency to lay stress 

 on unessential features and mere details of presenta- 

 tion. As an instance of exactness, it is shown how 

 the lowest common multiple need not be the least in 

 an arithmetical sense. We are glad to see a whole 

 page devoted to the distinction between an equation 

 and an identity. 



An attempt is made to define the order of the opera- 

 tions in an expression such as a-i-b x c. This can only 

 lead to confusion and mistake. The use of brackets 

 should be taught from the beginning. 



The book is poorly printed, but of a convenient si/e, 

 and will doubtless prove useful to those for whom it 

 is intended. R. W. H. T. H. 



Practical Chemistry and Physics. By J. Young, 

 A.R.C.S., F.C.Sl Pp. 108.' (Woolwich: Catter- 

 mole, 1903.) 



The space allotted to " physics " is so very limited 

 (9 pages out of 108) that the book may be considered 

 as one on practical chemistry. 



As a laboratory guide to chemical analysis then' 

 is little to distinguish it from many others deal- 

 ing with the same subject. The individual reactions 

 for the metals and acids are followed by analytical 

 tables and a few exercises in gravimetric and volu- 

 metric analysis. A page is usefully devoted to the 

 detection of impurities in common reagents. 



The utility of a book of this kind depends in the first 

 place on the student's previous training in practical 

 chemistry, for it would be out of the question to put 

 a beginner through a course which deals almost ex- 

 clusively with inorganic analysis ; in the second place, 

 it depends on the amount of supervision exercised by 

 the demonstrator, for there are neither drawings of 

 apparatus nor details of manipulation. Granted the 

 necessary training and supervision, one is nevertheless 

 led to suspect from observations dropped here and 

 there that it is not a quickening spirit of philosophic 

 inquiry which pervades the book, but the heavy atmo- 

 sphere of the examination room. " The test is too 

 delicate for ordinary use." " Be careful always to 

 add excess of the group reagent. Any less is quite 

 useless ; the ppt. not only fails to come, but afterwards 

 appears in the wrong place, besides giving rise to other 

 complications." " When the number of bases known 

 to be present has been found, the analysis can be 

 stopped." 



A reminiscence of the old stock question of the 



