June i8, 1891] 



NATURE 



147 



hasty, and ignores some of the main difficulties of the 

 subject, of attention and the voluntary control of the 

 thought-process, and of the abnormal modifications of 

 ideation in mental disease, sleep, and hypnosis. 



The unfolding of the third and final stage, voluntary 

 action, with which the volume concludes, offers little that 

 is noteworthy. The author adopts the new and growingly 

 fashionable view that all our active consciousness, sense 

 of muscular effort, and so forth, is the result of afferent 

 nerve processes, and he proceeds, much in the manner of 

 Miinsterberg, to resolve all volitional processes into com- 

 plexes of sensations and ideas, more particularly ideas 

 of movement. This seems to lead logically to the 

 denial of any distinctive active or volitional psychosis 

 answering to ideational or emotional psychosis ; and Dr. 

 Ziehen is not afraid to express this denial, and fortifies 

 his position by the debatable statement that psychiatry, 

 while acknowledging a special variety of intellectual and of 

 emotional disturbance, knows no such thing as a distinct 

 volitionary disturbance. It is to be added that the 

 exposition concludes with a particularly good discussion 

 of the final results of psycho-physical research. The 

 author here shows himself a genuine psychologist, and 

 while insisting upon the invariable concomitance of a 

 physiological factor in psychical phenomena, is so far 

 from regarding the psychical as a non-essential and 

 negligible accompaniment of the material process, that 

 he closes in a quite Kantian strain by reminding us that 

 the psychical chain is that which is known primarily and 

 immediately, and which as such niust always possess 

 more reality for us. J. S. 



ACHIEVEMENTS IN ENGINEERING. 

 Achievements in Engineering. By L. F. Vernon-Har- 

 court, M.InstC.E. (London : Seeley and Co., Limited, 

 1891.) 



1"^HE object of this book is to describe some of the 

 principal engineering works carried out during the 

 last fifty years at home and abroad. The author has " 

 avoided technical phraseology to a great extent, thus 

 making a very interesting subject as clear as may be 

 to the general reader. Much subject-matter has been 

 gleaned from many sources, and these are amply 

 enumerated in the preface. 



The London Metropolitan Railways and the New York 

 elevated railways are described in chapter i. The 

 growth of the Metropolitan system is very interesting, 

 and is traced from the opening of the first section from 

 Paddington to Farringdon Street in 1863 to the comple- 

 tion of the " Inner Circle " from the Mansion House to 

 Aldgate in 1884. The author states that when the Metro- 

 politan Railway was first designed, it was intended that 

 the traffic should be worked by smokeless, hot-water 

 locomotives not burning fuel, as it was supposed that the 

 trains would be small, and that "foreign" locomotives 

 would not travel over the line to any important extent. 

 This, however, was not carried out, and locomotives of 

 the ordinary type were adopted. The ventilation there- 

 fore proved defective, and even to this day improvement 

 is greatly needed in many sections. The bad atmosphere 

 is, of course, due to the locomotives in use, and the 

 emission of steam considerably adds to the nuisance. 

 NO. 1 1 29, VOL. 44] 



Locomotive engineering is surely able to cope with this 

 trouble. The dead weight of the trains might be con- 

 siderably reduced with advantage, and the engines de- 

 signed with ample condensing arrangements, even if the 

 latter had to be attached to the engine as a separate 

 vehicle. The boilers should, of course, be large enough 

 to steam well with the ordinary blower, so that all the 

 exhaust might be condensed. 



The Metropolitan Railway represents an engineering 

 achievement novel in many respects and made under 

 circumstances of peculiar difficulty. On the other hand, 

 the New York elevated railways illustrate how the 

 American engineers solved a similar problem in a very 

 different manner Owing to the cost of "burrowing 

 underground," as the author aptly describes it, they re- 

 jected the underground scheme, and for the same reason 

 a railway on an arched viaduct was also considered 

 undesirable. The railways have been carried along the 

 streets, raised above the street traffic on girders resting 

 upon wrought iron lattice columns standing at con- 

 venient places on the line of the curb of the pavements. 

 An illustration is given representing a street in New York 

 and the elevated railways running on each side. No 

 payment has been made for placing these columns along 

 the streets, and no compensation has been paid for 

 damages to residential property fronting the railways. 

 The author estimates the depreciation in value, due to 

 the presence of the railway, as not less than 50 per cent. 

 The cost per mile will therefore be considerably less than 

 in the case of the London Metropolitan Railway, in 

 which case all these items were heavily paid for. The 

 London railway cost about ;^575,ooo per mile, whereas 

 the New York elevated railways only cost about ^81,000 

 per mile. 



Chapter ii. describes railways across the Alps, the 

 Rocky Mountains, and the Andes, On p. 30 we find an 

 interesting diagram representing the gradients and 

 altitudes of the heavy portions of these lines, from which 

 it is evident that the lines in North and South America 

 are at higher elevations and are more subject to snow 

 than the highest of the Alpine railways, and more severe 

 gradients are to be found. Take, for instance, the heavy 

 gradient on the Mexican Railway, rising 6400 feet in 54 

 miles, the maximum gradient being i in 25. This portion 

 of the line is worked by Fairlie engines, which the author 

 attempts to describe on p. 56. 



The author in describing the Festiniog Railway says 

 that the traffic is worked up the long incline by " duplex 

 bogie engines, introduced in 1869, having two engines, 

 united by a tender common to the two, and hinged at the 

 centre." He goes on to say that these are called Fairlie 

 engines, after the name of their designer. The Fairlie 

 engines as used on the Mexican Railway certainly do 

 not agree with this description, nor does this description 

 agree with the usually accepted type of engine known 

 as the " Fairlie." The Fairlie engine consists of a special 

 type of boiler carried on bogies, one at each end. These 

 bogies have either four or six wheels, as the case may be ; 

 each bogie is fitted with steam cylinders and gear complete, 

 and all the wheels are coupled. The boiler has a smoke- 

 box at each end, and is fitted with fire-boxes in the centre? 

 being fired from the side. The steam pipes from the 

 boiler to the " steam " bogies are flexible, to allow the 



