3 o8 



NATURE 



[September 7, 191 1 



tions of the application of the Parsons steam turbine 

 In warships : their engines will develop more than 

 70,000 horse-power, and are estimated to drive vessels 

 weighing 26,400 tons at speeds approaching 30 knots 

 per hour for short periods and from 26 to 27 knots for 

 great distances. A table in the book shows that on 

 June 30, 1910, the Parsons type of turbine had been 

 applied to 333 steamships, and that their aggregate 

 horse-power exceeded 4,700,000. The first order for a 

 turbine destroyer was given by the British Admiralty 

 in 1899 ; the first merchant steamer fitted with turbine 

 machinery was built by Messrs. Denny in 1901 ; and 

 this simple statement of facts indicates the unprece- 

 dented progress which has been made by the new type 

 of marine steam engine. That progress proceeds at. 

 an accelerated rate; and in July, 191 1, 378 steam 

 vessels, with an aggregate of more than 5,800,000 

 horse-power in Parsons turbines, had been built or 

 were building. 



As time has passed and experience has been gained 

 modifications and improvements have naturally been 

 made by the inventor. It becomes obvious from the 

 story told by Mr. Richardson that from first to last 

 broad views, original research, and readiness to test 

 the relative merits of alternative arrangements, have 

 marked the work done by Sir Charles Parsons. The 

 mechanical ingenuity which has been displayed bv 

 him in the details of designs for steam turbines is 

 illustrated in many ways, and no one can fail to be 

 impressed by the mastery of fundamental principles 

 affecting the economic use of steam in engines of the 

 turbine type displayed by him, and the skill shown in 

 the design of mechanical engineering details, as well as 

 processes of manufacture, which have been no less 

 essential to the success of the new invention. In the 

 marine steam turbine the principles upon which 

 economy and efficiency depend arc, of course, identical 

 with those which hold good in steam turbines applied 

 for land purposes; but in connection with ship propul- 

 sion the designer has not only to take into account the 

 efficient use of si, -am in turbines, bul the general pro- 

 pulsive 1 fficiencj secured by the combination ol efficient 

 turbines with suitable screw propellers driven by tin- 

 turbines. In marine steam turbines it is consequently 

 found necessary to accept lower rates of revolution 

 than can be applied with advantage in land turbines 

 because a very rapid rate of rotation tends to dimin- 

 ished propeller-efficiency. This was one of the most 

 serious problems which had to be faced in the design 

 and construction of the Turbinia; its solution occupied 

 a long period, and led to main modifications in that 

 remarkable vessel before success was finally achieved 

 and the revolution in marine steam engines above 

 di sci ibed was made possible. 



Great differences exist in the conditions of service 

 of various classes of ships, and demand different de- 

 signs of propelling machinery. Hitherto the turbine 

 has been used almost entirely in vessels of high speed, 

 but its use in vessels oi moderati or low speed is now 

 sir Charles Parsons has 

 done pioneer work and has taken the lead in produi ing 

 practical examples. A cargo steamer <>l good type 

 (the Vespasian) has been purchased, her reciprocating 

 NO. 2184, VOL. 87] 



engine has been removed, and geared turbines have 

 been fitted instead. These turbines run much faster 

 than the propeller shafts, so that both the turbines 

 and the screw propellers can be given high efficiency. 

 A long period of working in actual service, as well as 

 measured mile trials, have shown a considerable gain 

 in economy and cargo capacity which was well worth 

 having in cargo vessels even of low speed. An- 

 other arrangement suitable for vessels of the " inter- 

 mediate " type — in which large passenger accommoda- 

 tion is combined with a great capacity for carrying 

 cargo and moderate speed — is known as the "combina- 

 tion system." Low-pressure turbines are associated 

 with reciprocating engines in such vessels, and the 

 expansion of the steam can thus be carried much 

 further than in engines of the reciprocating type. 

 In the Olympic and Titanic, the largest vessels at pre- 

 sent afloat in the mercantile marine, this combination 

 system has been applied, and it had previously proved 

 completely successful in vessels trading to Australia 

 and Canada. These are but a few of the examples 

 of the variety of the applications of the steam turbine 

 in marine propulsion which are illustrated in this 

 book; and other applications to mine ventilation, blast 

 furnace operations, and other services are also de- 

 scribed. The volume is handsomely produced and 

 beautifully illustrated. \Y. H. W. 



SYSTEMATIC BOTAS 1 . 

 Handbuch der systematischen Botanik. By Prof. 

 R. R. v. Wettstein. Zweite Aufiage. 1 Ilalfte. 

 Pp. 424. Price 20 marks. 2 Halfte. Pp. viii + 

 425-t|i5- Price 24 marks. (Leipzig und YVien : 

 F. Deuticke, 1910-11.) 



THE first edition of this work appeared in 1901, and 

 during the decade that has elapsed since, impor- 

 tant advances have been made in the investigation of 

 mam groups in the vegetable kingdom, more especi- 

 ally in the Schizophyta and the Gymnospermae. Thel 

 first part comprises the Cryptogams and Gymnospern® 

 preceded by a general introduction of somt litt\ pagffl 

 in which the more recent discoveries and theories are 

 discussed, 1 splained, or mentioned. As the title indi- 

 cates, the work is entirely devoted to systemaffi 

 botany, and it may be added that it is not intended 

 for the beginner, but for students already fairly well 

 versed in the rudiments ol the science. 



The main object lias been to construct, or rather to 

 improve, a classification on phylogenetic principles. 

 It is now generally admitted that it is impossible to 

 give expression to this in a linear arrangement, 

 especiall} as a monophyletic development can no longer 

 be sustained. On this point Dr. Wettstein is very 

 decided, lb accepts it as probable, however, that 

 the more highly organised plants — the Cormophytes — 



are ol tophyletii descent, though it cannot be 



claimed that this point has been settled. On the Other 

 hand, he considers that it is beyond doubt that the 

 so-called Thallophytcs include types of very different 

 origin. ( it with these views, Wettstein dis- 

 criminates seven "Stamme," or lines of development, 

 namely, (i) Myxophyta ; (ii) Schizophyta; liii) Zygo- 



