February ig, 1920] 



NATURE 



(357 



readers have little to gain in the matter of sub- 

 stantial knowledgfe from their Italian competitors. 

 The standard of the book is very much on a level 

 with the swarm of weekly illustrated popular 

 journals which may be seen in the waiting-room 

 of an English aircraft factory or on the table of 

 the library at Central House or of the Royal Aero- 

 nautical Society. As an introduction to practical 

 aeronautics, the book will provide the Italian 

 student with an insight into the mass of detailed in- 

 formation which is required by aircraft mechanics 

 and pilots. The best portion is undoubtedly the de- 

 scriptive account of the different types of aero- 

 plane and their component parts, and as the 

 machines selected for illustration are mainly of 

 Continental make, the book may be of use to Eng- 

 lish readers for purposes of comparison. As 

 regards the theoretical side, the treatment is very 

 elementary, and imperfect formulae and calcula- 

 tions are indeed abundant, but most of these are 

 not much more than replicas of what one can find 

 in our elementary school text-books on geometry 

 and mechanics. The misfortune of this practice 

 is that things look like new principles which are 

 as old as the hills. But we in England cannot say 

 much when one of our own weekly journals has 

 devoted a glowing paragraph to the announce- 

 ment that an American professor has discovered 

 that two similarly electrified bodies can overcome 

 gravity and repel each other. 



In the sections dealing with pressures on com- 

 ponent parts of aeroplanes, considerable promin- 

 ence is given to Eiffel's diagrams of experimental 

 results. The main difficulty in practice is that the 

 pressures on the various elements of an aeroplane 

 are not mutually independent, and for this reason 

 we should have preferred a section dealing with the 

 wind channel and its use, since this has become 

 an indispensable adjunct to our aircraft factories. 



The so-called " stability " which figures in a few 

 sections does not in any way represent stability 

 proper as studied in this country and tested experi- 

 mentally at Teddington and Farnborough. 



The sections dealing with navigation describe 

 the usual instruments found on aeroplanes, and 

 methods which do the ordinary, easy things, such 

 as determining the position and velocity of an 

 aeroplane when seen from the ground, which is 

 very different from enabling a pilot to find his way 

 in a fog or on a dark night. A lot of algebra is ex- 

 pended (p. 876) over a method of finding wind 

 velocity by making an aeroplane fly in a quadri- 

 lateral path when ruler and compass would do the 

 whole thing at once. The section on the seaplane 

 contains the usual theory of the metacentre ; the 

 further developments required to take account of 

 the effects of air resistance are briefly epitomised. 

 NO. 262:5, VOL. IO4I 



On the whole, the book fairly well meets the 

 requirements of the average pilot, mechanic, or 

 draughtsman who is in a position to leave more 

 theoretical considerations in the hands of scientific 

 experts (if he can find them). 



In the Attx dei Lincei, xxviii., (i), 7, 8, Dr. 

 Oreste Mattirolo considers the use of wood in 

 the longitudinal bars of an aeroplane, with special 

 reference to the effects of growth on the strength 

 of the timber. During the war the timber used 

 in the construction of aeroplanes was tested and 

 examined by the author, and the existing methods 

 were found to be inadequate. Dr. Mattirolo directs 

 especial attention to the effect of climatic and 

 seasonal conditions on the growth of the rings, 

 and to the difficulty of locating weaknesses in the 

 structure, and he cites two cases of accidents in 

 which the wood was sent for his inspection and the 

 defects were discovered too late. He recommends 

 that now the demand for aeroplanes has lessened 

 the longitudinal beams of the wings should no 

 longer be made of wood. It is interesting to 

 note that similar investigations in this country 

 have been carried out in greater detail at Farn- 

 borough and elsewhere, though a number of 

 problems still await solution in this as in other 

 aeronautical investigations. 



In another issue of the Atti dei Lincei (xxviii., 

 I, 2), Dr. Mario Tenani refers to the influence of 

 the density of the air on the efficiency of aero- 

 planes, and quotes the ordinary laws of variation 

 of density with pressure, temperature, and altitude 

 in support of his plea regarding the im-portance of 

 a subject which has received much attention in our 

 country both in connection with airships and in ex- 

 periments with variable propellers at Farnborough. 



Meteorological difficulties should not be so seri- 

 ous in sunny Italy as in our land of fogs, though 

 the Italian mountains may be set against the 

 brighter climate. At the Pisa meeting of the 

 Italian equivalent of our British Association, a 

 paper on weather prediction was read by Prof. 

 Filippo Eredia, at the end of which a resolution 

 was passed advocating the joint action of the 

 Ministries of Agriculture, Industry, and Commerce 

 in co-ordination with the Air Department to pro- 

 mote researches in weather prediction with the 

 view of furthering the development of commercial 

 aviation. 



Papers dealing with aeronautical subjects have, 

 however, been conspicuous by their absence from 

 the proceedings of learned societies in this and 

 other countries, and the Atti dei Lincei has been 

 no exception to the rule. If this is a result of the 

 war we may welcome the three papers as an 

 augury for a better state of affairs in the future. 



G. H. Bryan. 



