Ki{\ir:\\s. 



AERONAUTICS. 



Niitiinil Shihiltty ill Aeroplanes. — By W. Lie MAliKii. 

 4() pa^os. .53 illustrations. 7i-iii. X4'f-in. 



(E. & F. N. Spon. Price 1/6.) 



This book is the expression of the personal opinion of the 

 author on the subject forming the title. There is also a rough 

 description of a machine designed in accordance with prin- 

 ciples which he has deduced from experiments madr with 

 small gliders. 



His main deduction is tliat machines with short wing span 

 and low centre of gravity will make the best and most 

 "etficient " machines. 



The author seems to be under the impression that liis 

 principles have never been tried; he is very much mistaken on 

 lliis point. 



As to the deductions themselves, short span and very low 

 I L litre of gravity are almost diametrically opposed to the 

 generally accepted necessary conditions for proper efficiency, 

 and the propriety of these conditions, besides being demon- 

 strable by laboratory experiment, is fully confirmed by the 

 results in practice. 



It is also a fairly well-known fact that by increasing or 

 adding to the resistances of an aeroplane, one can increase its 

 stability, but at the expense of its efficiency or the power 

 necessary for flight. 



The only proper deduction from the author's experiments is 

 tliat a machine constructed to the author's designs, when 

 once up, could, on a very calm day. form a steady glide to 

 earth, (somewhat steep, very possibly), but that such an 

 inefficient machine ever would "get up" is, to say the least, 

 problematical. .,- ... ,- ,. 



Liinglcy Memoir o/ Mecliaiiieul Fti^lit. 

 (Published by the Smithsonian Institution, W'a.shingtoni, 



In this book we have the long looked for full description of 

 .ill the wonderful and patient experimental work of the late 

 Mr. Langley. The work, which has taken eight years to 

 complete, is a monument to the single-minded thoroughness of 

 the experimenter, and to the untiring energy of his most able 

 assistant, Mr. Manley, and the result far exceeds the most 

 sanguine expectations. 



The size of the work precludes any adequate description of 

 its contents ; suffice it therefore to remark that it consists of 

 over three hundred p.iges of text, written in a clear, concise 

 and interesting manner, and well printed on good paper. There 

 are in addition one hundred and one full page plates, all clearly 

 reproduced from photographs. These shew various rubber 

 driven models (there are thirty-one of these), power models 

 (four of thescl. the same in flight, launching apparatus, man- 

 carrying machines, surfaces, automatic equilibrium devices, 

 boilers, and numerous others, most of them having their 

 details shewn separately. 



Here may be read the troubles attendant on making light 

 motors, and how, (in 1900). when searching over Europe for a 

 light petrol motor, all the builders were agreed that a light 

 twelve horse-power motor could not be built to weigh less than 

 two hundred and twenty to three hundred and thirty poimds, 

 and how^ finally Mr. Manley personally assumed the responsi- 

 bility of making the same, and successfully produced one of 

 twentv-four horsepower weighing one hundred and twenty 

 pounds only, a result comparable with present engines. 



To those who interest themseh>es in " Flight " this book is 

 essential. .,.^ ^^._ ^_ ^^_ 



ciii:mistrv. 



The Relative \'i)li(iiies of the Atuiiis of Cartmii, Hydrogen 



and Oxygen, u-lien in Combination. — By H.wvkswortu 



Collins, B.A. (Cantab.). 107 pages. 8i-in.X5A-in. 



(Morton iS: Hurt. Price 7 6 net.) 



To Hermann Kopp is due the honour of having made the 

 first systematic attempt to discover the relation between the 

 chemical constitution and the physical properties of bodies. 

 .\mongst these properties he gave perhaps greatest attention 

 to that of molecular volume. He concluded that molecular 

 volume is an additive property, i.e.. that the volume of an atom 

 in combination is a fixed quantity (within certain limits) at 

 any temperature, and that the volume of any molecule is the 

 sum of the volumes of its constituent atoms. He assigned 

 the following values to the atoms of Carbon, Hydrogen and 

 Oxygen— C = ll;H=5-5;0 = 12-2 or 7-S according to 

 whether it is carbonyl-oxygenor hydroxyloxygen. Researches 

 carried out since the time of Kopp have shown that the matter 

 is not so simple as this : the arrangement of the atoms has a 

 decided influence upon the molecular volume, (as Kopp 

 recognised in the case of oxygen), isomeric bodies by no 

 means always having the same molecular volumes. 



The author of the present work has given many years of 

 study to the solution of this problem, seeking for some 

 consistent method of interpreting the values for the molecular 

 volumes of various compounds obtained by experimental 

 chemists. And as a result of this study, he has devised a 

 method of calculating the molecular volumes of various 

 bodies with a (luite remarkable degree of accuracy. In the 

 present work he deals only with compounds containing 

 carbon, hydrcjgen and oxygen. He finds that the molecular 

 volumes of such bodies at 15 C may be calculated by giving 

 the following values to these atoms — C= -71, or in some 

 cases 8-0; H = 15-25, 12-22. 9-<J5, or 5-76; O = 2-51, 4-45 

 or 7 • 53 ; the different values of the elements being assigned 

 according to certain fixed rules. 



The fact that it is necessary to give different values to the 

 atoms of hydrogen and oxygen, he explains by the theory that 

 the four valencies of carbon arc not equal, and that the 

 volumes of other atoms differ according to which carbon 

 valence they are combined with. There are immense diflicnl- 

 ties in the way of accepting this theory, however, and the fact 

 discovered by Mr. Collins, that in order to calculate 

 accurately the molecular volumes of carbon compounds we 

 must assign differing values to the hydrogen and oxygen atoms 

 may be explained otherwise, and we think, more easily. For, 

 in the first place, there is the probability that the volume 

 occupied by an atom is affected by neighbouring atoms ; and, 

 in the second place, we have shown elsewhere ("On the 

 Calculation of Thermo-Chemical Constants") that the true 

 atomic values for any physico-chemical property are unobtain- 

 able in the present state of knowledge, the supposed atomic 

 values obtained being really the differences between the 

 values of such atoms and their linkages and the influences due 

 to the linkages broken by the introduction of these atoms into 

 the molecule. Regarding Mr. Collins' values of the atomic 

 volumes as the values of such differences, his work is of 

 considerable worth. So little is really known of what may 

 be termed the physics of molecules, that every addition to 

 this subject is especially welcome. Physical chemists will 

 doubtless give Mr. Collins' interesting book the careful 

 attention it deserves. ^_ ^^ Rudgrove. 



