August 30, 1900] 



NA TURE 



41T 



Mr. Mordey, on account of lack of time, dealt shortly 

 with the drop of pressure along the rails of an electric 

 tramway, and stated that he had found that when the 

 length was even 28 miles, the difference of potential be- 

 tween any parts of the rails and the generating station 

 could be kept down to 7 volts ; and he referred to the 

 much greater attention that was given in England than 

 in America to reducing the maximum drop of pressure 

 along tramway rails. The employment of rotary trans- 

 formers, as on the new Central London Railway, he 

 deprecated as a makeshift, and suggested that, if the 

 cost of all the transformers employed along the 6 miles 

 of the route had been capitalised, it would have paid the 

 company to have employed far thicker conductors. As 

 regards the difficulty arising from the capacity of long 

 underground cables traversed with alternate current, he 

 pointed out that no difficulty in overcoming the effects of 

 capacity had ever been met with in dealing with the 250 

 miles of underground cable in St. Petersburg. The 

 Board of Trade had succeeded in using such instru- 

 ments in their laboratory at Westminster that no inter- 

 ference could be caused by the construction of any electric 

 tramway in the neighbourhood ; therefore, he deplored 

 the resistance that had been successfully offered a few 

 years ago by a London college to the passing of a Bill for 

 the construction of an underground electric railway near 

 that college. 



Mr. Mailloux pointed out that the small power-factor 

 obtainable with alternate current motors, and the greater 

 change in speed with a change in the E.M.F. that was ex- 

 perienced with alternate current than with direct current 

 motors, was a serious objection to the employment of the 

 former, and he instanced a case where the large current 

 that was necessary for starting an alternate current motor 

 had led him to adopt a direct current system in a sugar 

 factory where 2000 horse-power was employed. The 

 Fire Insurance Rules in the United States, which com- 

 pelled the use of iron conduits, but which did not require 

 that both the going and return conductors should be 

 enclosed in the same iron tube— a condition, however, 

 rendered necessary if alternate currents were employed 

 — led to an important economy being obtained by using 

 two separate conductors in separate iron tubes, which 

 was, of course, quite possible with a direct current. 



Prof. S. p. Thompson expressed his surprise that in 

 wiring ships for electric lighting, where the possible 

 disturbance of the compasses was a vital consideration, 

 the direct current and two pole machines, the worst 

 type to use, had been frequently employed even by the 

 best firms, like that of Messrs. Siemens. He looked 

 forward to seeing the use of multipolar machines on 

 board ship, and of the alternating current ; for not only 

 would the compasses be then secure from disturbance, 

 but there would be much greater freedom from electrolysis 

 in damp places, and therefore of fire. He pointed out 

 that the alternate current lent itself so readily to the use 

 of efficient lota voltage glow lamps combined with 

 economic ^I'j^/t voltage transmission ; and finally that, 

 since it was impossible to employ any device to screen a 

 magnetic observatory from magnetic disturbance, since 

 such a device would cut off the effects produced by 

 variations of the earth's magnetism which the observatory 

 existed to measure, there was a strong reason for running 

 electric tramways with alternating current in any city 

 where a magnetic observatory existed. 



At the close of the preceding discussion, M. Hospi- 

 tal ier, Mr. Gavey, Mr. Hering and General Webber 

 referred to points of special and novel interest in the 

 several electrical sections of the Exhibition, in connection 

 with which they had served as jurors ; and in the after- 

 noon these gentlemen acted as guides in taking parties 

 of members of the two electrical societies to view the 

 exhibits which had been specially mentioned. 



NO. 1609, VOL. 62] 



THREE BOOKS OF POPULAR NATURAL 

 HISTORY} 



MR. HUDSON has never written any book that is 

 not extremely pleasant to read, though since he- 

 settled in England he has never had so much to tell us 

 as was told in his " Naturalist in La Plata." That book, 

 though it may not be his own favourite, will always, if 

 we are not mistaken, be reckoned as his best ; and the 

 reason is simply that it treated of animal life among 

 which he was entirely at home, and of which we knew 

 little or nothing. His English books have not this 

 quality, though they have many other excellences. The 

 one before us, for example, is charmingly written, full of 

 grace and feeling, touched with a tender and sympathetic 

 imagination, made piquant by a certain quite inoffensive 

 egoism ; but, as we read in his pages of the South 

 Downs, we are forced to recognise the fact that he is not 

 of them. He is a stranger there — a most appreciative 

 one, it is true — but still a stranger. It is perhaps given- 

 to few who have not been bred among the Downs to- 

 enter fully into their spirit, and we will not deny that 

 Mr. Hudson, rambling alone through their sweet air and 

 lying on their delicious turf, has caught it as none could 

 do without rare gifts of sympathy and observation ; yet 

 there is something missing. , 



It IS not pleasant to have to find fault with a book so- 

 readable ; but a naturalist cannot but regret that Mr. 

 Hudson should have given himself up so entirely to 

 impressions throughout a volume of just three hundred 

 pages, that no real contribution to natural history is to- 

 be found in them. He notices an interesting point, 

 writes a charming paragraph about it, and leaves it,, 

 sometimes without making it clear what plant or creature 

 he is talking about. To take an example : he has ob- 

 served that the banded variety of Helix neinoralis is 

 almost the only one to be found on the high downs, andi 

 that its bright coloration does not save it from the 

 thrushes ; but he does not pursue this fact, which has- 

 attracted the attention of conchologists and suggested! 

 at least one interesting explanation. Snail life on the 

 downs is, indeed, so extraordinarily abundant, that a book, 

 which contains so much pleasant reading about the down 

 turf is hardly complete without a chapter specially de- 

 voted to it. The same may be said of his remarks on- 

 insect life ; he tells us of the common blue butterfly,, 

 and its habit of clinging to the bents, but of other blues 

 he says nothing ; a skipper is mentioned, but we are 

 left in the dark as to the species. In writing of a certain 

 fly, he declares that neither books nor entomologists 

 have been able to tell him its name, and leaves it with 

 a few words of good-natured contempt for the specialism, 

 of the present age. A little more exactness in a book 

 by a naturalist, which naturalists may be expected to 

 read, would have greatly added to its permanent value. 

 Even men of letters may complain when they find an- 

 allusion to Arthur Young's famous " Tour through Great 

 Britain in 1727." What book can this be ? 



The best chapters are those which deal with the birds 

 and the human beings of the downs. Shepherds and 

 shepherd boys are delightfully pictured ; and Mr. 

 Hudson has discovered for himself the pleasing habit of 

 the ruddy-faced shepherd lads in adorning themselves 

 with wild flowers. About the birds he has plenty to tell 

 us — it is his own subject ; and the chapter on " Shep- 

 herds and Wheat-ears " will be read by all ornithologists 

 with mingled pleasure and pain. All that he writes of 

 the singers of the downland is beautiful and true; per- 

 haps the songs of the stonechat and whinchat have never 



> "Nature in Downland." By W. H. Hudson. Pp. xii -f- 307. (London: 

 Longmans, Green and Co., 1900 ) 



"The Birds of Cheshire.'^ By T. A. Coward and Charles Oldham. 

 Pp. 278. (Manchester : Sherratt and Hughes, 1900.) 



"In Birdland, with Field-glass and Camera." By Oliver G. Pike. 

 Pp. xvi -I- 280. (London : T. Fisher Unwin, 1900.) 



