January 20, 19 10] 



NA TURE 



335 



the wind still remains one of the most fascinating 

 problems in agricultural engineering'. The trans- 

 mission of the current is next described. In this 

 chapter, as in the preceding one, there are a number 

 of diagrams to illustrate the principle of the apparatus, 

 besides a good deal of information that will be useful 

 when anything goes wrong. These chapters take up 

 half the book. 



The author then comes to the very important sub- 

 ject, How can electrical energy be utilised on the 

 farm ? The two applications developed in detail are 

 the driving of engines and lighting. Its use for 

 driving the machinery in the farm buildings, the chaff- 

 cutter, the pulper, and so on, is obvious, but the 

 author goes still further and describes a number of 

 applications which as yet have only rarely been made. 

 Some forty pages are devoted to electrical ploughing, 

 the first attempts at which were made so far back as 

 1879, although as a practicable method nothing was 

 done until 1894, when a start was made both in Italy 

 and in Germany. The methods are almost exactly 

 the same as for steam ploughing; indeed, the idea 

 is taken direct from the steam plough but elec- 

 tricity' is substituted for steam as the hauling power. 

 In one system there are two electric motors at oppo- 

 site ends of the furrows hauling the plough ; in the 

 other an anchor is used and there is one motor 

 only. The problem here is really very simple ; if 

 steam ploughing is known to be beneficial electric 

 ploughing will be equally so, and the question resolves 

 itself solely into the relative cost of the power. Indeed, 

 this statement holds true of most of the applica- 

 tions recommended by the author. His electrical 

 threshing machine, for instance, is the ordinary 

 machine driven by electrical power, so also are the 

 refrigerating machines, pumps, and sawmills. 



The application of electricity as a source of light 

 affords a great deal of scope for the author's ingenuity, 

 since many of the farm operations, such as the milk- 

 ing and feeding of dairy cows, have to be carried out 

 before daylight during part of the year. Suitable 

 lamps are suggested for the various buildings. 



There is also a useful chapter on treatment of 

 accidents caused by electricity and precautions to be 

 taken in order to avoid accidents. Lastly we have 

 some well-illustrated descriptions of farms where 

 some of these applications are in actual use. 

 Probably to the English reader this is the most 

 interesting chapter of all. Whether we may expect 

 to see electricity utilised on British farms is another 

 matter. Up to the present electricity has simply been 

 taking the place of steam to work the old imple- 

 ments originally designed for human or horse labour. 

 Probably before it comes into common use in agri- 

 culture our implements will have to be re-modelled 

 and adapted to electrical power. In the cases 

 described by the author water power is avail- 

 able or electric current is being transmitted through 

 the district. The farmer can calculate exactly how 

 much his power will cost him and whether it is 

 worth while replacing the oil engine by a motor. 



The book forms a useful contribution to agricul- 

 tural engineering, and will make verv suggestive 

 reading for the thoughtful agriculturist. 

 NO. 2099, VOL. 82] 



THE PHEXOMENA OF THE EARTH'S 

 SURFACE. 

 Physiography for Schools. By R. D. Salisbur)'. Pp. 

 viii + 530. (London : John Murray, 1909.) Price 6s. 

 net. 



THIS book may be looked on as a reduction of the 

 advanced course by the same author. Prof. 

 Salisbury states in his preface that he differs from 

 other writers on physical geography "as to the points 

 upon which emphasis should be laid and the objects 

 to be attained." But it would require careful reading 

 to find out in what matters of principle this test- 

 book differs from others by American authors, and we 

 fancy that schools will adopt one book or the other 

 lather from some attraction between the teacher and 

 the author than from any preference as to mode of 

 treatment. We miss the "cycle of erosion," and its 

 accompaniment, the "peneplain," which have taken 

 quite an affectionate hold upon our minds ; but we 

 meet the "mesa" and the "monadnock," and the 

 really awkward adjective "piedmont," this last being 

 used without explanation, and applied to certain plains 

 as well as glaciers. 



Valley-forms are agreeably dealt with as expres- 

 sions of youth, maturity, or old age, and the excellent 

 chapter on the "Work of Running W'ater " may be 

 taken as typical of the first part of the book. We 

 should not like to spare any of its numerous maps and 

 illustrations, which bring before us all manner of 

 details in the history of a stream; at the same time, 

 we should like to hear more from the author, whose 

 lines are modestly dovetailed in between them. A 

 specially effective feature of part i. is the insertion of 

 some twenty contoured maps in colour, often on a 

 scale of one inch to one mile, selected from the topo- 

 graphic sheets of the United States Geological Survey. 

 With this example before us, must we wait long for a 

 European work, similarly illustrated from our British 

 contoured maps, and also, perhaps, from the I :20o,ooo 

 sheets of the Austrian Military Institute? 



The later parts of the book, on "Earth Relations," 

 "The Atmosphere," and "The Ocean," do not lend 

 themselves so temptingly to illustration ; but numerous 

 diagrams and charts are given, and the instruction 

 in thetextis singularly clear. Fig. 351, showing how 

 the length of a degree is related to polar flattening, 

 requires more thought than a child is likely to bring 

 to bear on it. Perhaps a diagram showing how 

 longer distances have to be traversed as we go north- 

 ward, in order to shift the altitude of the pole star 

 bv so many degrees, might have been simpler, in illus- 

 tration of the description on the following page. Snow 

 crystals are named " snowflakes " in the title of Fig. 

 176 ; and Fig. 450 shows the sounding-tube, and not 

 the line, as stated. We fear that the abrupt question 

 to the reader, "Why not use a rope, instead of a wire, 

 in sounding?" may be taken as a suggestion from 

 the gifted author, and may turn the young mind in a 

 wrong direction. But there is little to criticise in this 

 closely- written text-book. We return to the pages on 

 the work of rivers and of ice with special pleasure. 

 The author thinks (p. 168) that plastic flow does not 

 plav anv real part in glacier motion, and lays stress 



