in evolution. These are the seven divisions of the book, which aims at providing a foundation suitable for the further study of one or more of the many branches. We Prof. Calkins has selected his material judiciously, and by exercising unusual restraint he has kept his introduction within appropriately small dimensions. His treatment is beautifully clear throughout and he drives his nails home. Only in a few cases, e.g. in the last chapter, is the treatment too short to be of great use to the ordinary student, who must always have a certain amount of solid concrete stuff to chew at. have two or three other suggestions to makethough it is a little like trying to adorn the rose. We have a strong impression that general biology deals with the fundamental principles not of living matter, as the author insists, but of organisms. We do not admire the striking first figure in which Prof. Calkins makes general biology the centre of twelve sub-sciences, duplicated for plants and animals, for the arrangement of these does not appeal to us and we have grave doubts regarding the neurology of plants. There are a few typographical errors, which should be seen to: the function of the "sdnalgs" is immaterial, but Dalton instead of Galton (both in the text and the index) is awkward. These are pin-point blemishes on a work of great excellence, which is sure to be found very useful. Many of the new figures deserve great praise, e.g. the stereogram of the earthworm for its utility and the picture of J. A. T. Hydra for its beaut" net. As might be expected, Mr. Orwin has made this a very valuable book. Many works on bookkeeping are arid and unconvincing because the transactions described are obviously artificial, but here we come into contact with the actual thing, and feel that the author is writing from large practical experience of farm accounts. The introduction demonstrates that the farmer is a manufacturer, not a merchant, so that his book-keeping should be conducted on the principle of tracing the cost of production right through to the time of sale. Farm valuations are then lucidly explained, and illustrated-as are all the other topics -"from actual accounts kept by tenant-farmers in various parts of Britain." The following chapter on farm records deals with manual and horse labour, foods and manures. Next comes a clear and detailed description of the way books ought to be kept, accounts closed, and the figures used for construction of a profit and loss account and balance sheet. The final chapter sets forth some of the conclusions and deductions that may be arrived at by study of the year's accounts. An index is appended. The work is primarily intended for use in farm institutes, and should be well within the comprehension of full-time county council students in agriculture, though probably too difficult for short coursers, whose school education has often largely evaporated. The value of the book would be enhanced by the addition of exercises for class work. J. R. A.-D. Who's Who, 1915. An Annual Biographical Dictionary, with which is incorporated "Men and Women of the Time." Pp. xxx+2376. (London A. and C. Black, Ltd.) Price 15s. net. We have again to note an increase in the size of this invaluable work of reference. The many excellent characteristics of this annual are familiar to all who take part in the world's activities; and it will be enough to remind readers of NATURE that it contains biographies of distinguished men of science, including, for instance, the fellows of the Royal Society, and those occupying important professorial and professional positions in this and other countries. Magnetism and Electricity, including the Principles of Electrical Measurements. By S. S. Richardson. Pp. ix +598. New and revised edition. (London: Blackie and Son, Ltd., 1914.) Price 4s. 6d. THE first edition of Mr. Richardson's book was reviewed in the issue of NATURE for December 31, 1908 (vol. lxxix., p. 246), and a description of its chief characteristics was then given. The whole of the text of the new edition has been revised, several portions have been re-written, and a chapdynamos and motors has been added. ter on the principles underlying the action of LETTERS TO THE EDITOR. [The Editor does not hold himself responsible for opinions expressed by his correspondents. Neither can he undertake to return, or to correspond with the writers of, rejected manuscripts intended for this or any other part of NATURE. No notice is taken of anonymous communications.] The Appley Bridge Meteorite. IN NATURE of November 5, 1914, Mr. W. F. Denning gave an account of the meteorite of October 13, 1914, in which he mentions that the object had been found, and was then at the Godlee Observatory, Manchester. The object which fell at Appley Bridge belongs to the aerolites or stony meteorites, and not to the siderites or irons. In appearance there is the striking meteoric features of deep thumb marks-piezoglyphsand the general coating a dark brown to black. This was in distinct contrast to the interior, which was of a light grey colour. In general the figure gave one the impression of its being a segment of a spherical shell, the dimensions being : It is certainly a remarkable object, as on a comparison with the list of meteorites recorded in Great Britain, published in the British Museum Guide to Meteorites, there is only one given of greater weight, that fell at Wold Cottage in Yorkshire in 1795. The outer coating, which varies from a very thin film to nearly 2 mm. in thickness, presents a very finely-pitted surface, with evidence of a tendency to show lines of movement, as though the heated skin was being pushed backwards from the direction of motion. The portions which had become fused showed a dark glazed or shiny surface, this evidently being the forward end, and the portion to which the heat from the compressed air in front of it was most effective. The appearance of the pittings suggest that the heating of the surface was the means of liberating some portions of the structure of the mass, and that these would provide what is seen as the trail of the meteor after it has passed in its flight through the air, being the continued glow of the heated emissions by combination with the oxygen in the air. There is evidence that some portions of the surface expected from the mineralogical contents. A magnetic examination of the mass as a whole gave no appreciable effect, although a search amongst the dust which accumulated from the rubbing of the two pieces, indicated portions of magnetic nature though small in amount which proved to be metallic iron. The pyritic material contains nickel as well as iron, portions being crystalline, the olivine being of a pale yellowish-green colour, whilst the enstatite is whitish or grey. The proportions of the minerals worked out on the basis of the composition and solubility are approximately : Pyritic and metallic matter Olivine 5:07 315 63-43 Appley Bridge Aerolite, October 13, 1914. had only come into contact with the air during the later portion of its traverse. These regions have all the appearance of flakes of the outer skin having been broken away, a slight tarnishing of the pyrites, if at a distance from the edge of the fracture or slight fusing when close to the general outer coating, indicating a removal of portions of outer layers of the mass. This is quite in keeping with the assumption that the fragments were split off at the time of the apparent burst in the air, at about twenty miles' altitude, as from that position the speed of the meteor would be so much reduced by the compressional friction, that it would be losing more heat than gaining. The fractured surface on an inspection appeared to be made up of a glittering mass of white and yellow points in a grey setting. These proved to be chiefly pyrites, and their presence accounted for the apparent great weight according to the size. The specific gravity of the mass determined from a fragment was 3.33, and is in accord with what would be Nickel With oxygen in combina The accompanying illustration shows the front view of the aerolite with the thumb marks. WILLIAM C. JENKINS. 11 Upper Lloyd Street, Moss Side, Manchester, December 27, 1914. 66 A Suggested Definition of Magnetic Permanence." FROM time to time accounts appear of experiments on new kinds of steel which have been undertaken with the object of determining the most suitable material from which to construct a permanent magnet. Experiments of my own on this subject, made a good many years ago, led me to think that it would be an advantage if precision could be given to the term "permanence" in magnetism, and inasmuch as a high coercive force is the principal factor in the preservation of the magnetism in a magnet the measure of permanence, I think, might be taken as the coercive force per unit of residual magnetic_intensity. Thus the inclination of the intensity-field curve as it falls from residual to zero intensity indicates what the permanence of the magnet may be expected to be. According to this definition the permanence of soft iron is about 0.0024. Recent experiments by Miss Margaret Moir (Phil. Mag., November, 1914) on chrome steel give the high permanence of 0.165, or, if the calculation is made from final residual magnetism after shocks and changes of temperature, of 0-201. These examples show a range of permanence from 0.0024 to 0-201, in the ratio of 1 to 84, but it is not unlikely that these limits may be exceeded. J. R. ASHWORTH. 55 King Street South, Rochdale. EUROPEAN AERODYNAMICAL LABORATORIES.1 IN N the summer of 1913 Prof. Zahm and Lieutenant Hunsaker, of the United States, visited the European aerodynamical laboratories in order to study apparatus and methods in use, before finally deciding on the details of the material to be 1 Report on European Aeronautical Laboratories. By Dr. A. F. Zabr Smithsonian Miscellaneous Collections, vol. lxii., No. 3. (Washington: Smithsonian Institution, 1914.) FIG. 1.-Longitudinal section of the large wind tunnel, Eiffel Aerodynamical Laboratory. as the re-opening of the Langley Laboratory cannot yet be said to be effective. The present position appears to be that a scheme of work has been submitted to an advisory board which advocates the provision of a wind tunnel and of facilities for large-scale experiments, and it appears to be intended that the work of the Lang are reproduced in Figs. 1, 2, and 3. In M. Eiffel's apparatus the air current traverses the centre of a large room, and one of its advantages is the facility with which models can be moved into and out of the air current. It is further claimed by M. Eiffel that the absence of walls is an advantage in removing some constraint usual in wind tunnels. In the Göttingen installation, Figs. 2 and 3, air The wind channels at the National Physical Laboratory were recently described in NATURE, and little need be reproduced of Prof. Zahm's report. He describes the aerodynamic current as the steadiest in the world with limits of per cent. in both time and space. The steadiness of the air-flow in the Eiffel apparatus is stated to be 2 per cent. in time and space. Prof. Zahm claims priority for the use of bellcrank balances for aerodynamical work, and says that he is of opinion that several new types can be devised which shall be equally precise with those at the National Physical Laboratory, and probably more expeditious. Such new types have been in contemplation since first devising the bellcrank aerodynamic balance in 1902. It is therefore probable that the balance for the wind tunnel of the Langley Laboratory will be of the bell-crank type, but will differ in detail from those in use in Europe at the present time. In reference to full-scale experiments, Prof. Zahm considers that the Royal Aircraft Factory most nearly approaches the organisation projected for large-scale work at the Langley Laboratory, though he excludes the possibility of manufacturing aircraft in considerable numbers. He considers the outcome of the large-scale experiments at the Royal Aircraft Factory to be the production of a stable, efficient, and safe biplane. Reports from the seat of war add strong support to this view. A considerable amount of space in the report is devoted to a description of the apparatus for largescale experiments at St. Cyr, near Paris, and the remark is made that the relative importance of such large-scale tests as can be carried out on moving carriages, as compared with model tests or full-scale flights with instruments mounted on the aeroplane, has yet to be determined. The difficulties of experiment are indicated by the statement that the lift measurements on simple lifting surfaces are 5 per cent. in error, whilst the resistance measurements are much less accurate. It is interesting to note that at the time of the visit, no aerodynamical experiments had been made in Germany other than those at Göttingen, but that arrangements were almost completed for large-scale work at Adlershof, near Berlin. For further particulars reference should be made to the original report. CHEMISTRY OF WHEAT AND FLOUR. FEWER than ten years ago most millers and bakers would have scoffed at the idea of there being any connection between chemistry and wheat or flour, and even the man of science would have admitted that the application of chemistry to such problems as the cereals presented was in its earliest infancy. Progress, however, has come rapidly and not only is the actual knowledge in the field now very considerable, but it has been already of the utmost value when applied in practice, so that scientific milling as well as scientific baking have made great strides. 1 It is safe to forecast that chemistry is destined to play as important a part in the manufacture of flour in the future as mechanical science has done in the past, and it is satisfactory to note that there is every indication that Britain is more than prepared to hold her own in this development. Flour is primarily a starchy material, but those characteristic properties which enable it to be made into bread are due almost entirely to the presence of some 10 per cent. of nitrogenous material-the gluten. Consequently, from the point of view of the miller and the baker, gluten is the all-important constituent of flour. Somewhat irrationally gluten has come to be regarded as such also by the would-be food expert, who overlooks the fact that bread is eaten primarily, not as a source of protein, but as an easily digestible, attractive form of starch. The man in the street properly regards bread as equivalent to rice, potatoes, or the like, rather than as a substitute for meat; it is, therefore, not surprising that the would-be agitators have failed. Gluten, which is readily obtained from a piece of dough by washing and kneading it in a stream of water until the starch has been removed, is a light brown material which has considerable elasticity. From the chemical aspect, gluten is a mixture of several proteins, of which two only are of importance so far as its bread-making properties are concerned. These are named gliadin and glutenin, and they are apparently chemical entities so far as this description can be applied to any protein. Gluten is characterised by the properties of ductility and tenacity so that in dough it can entangle air in its cavities, which swell during fermentation and still more when heat is applied. Such Wheat grown in different parts of the world is far from being always the same nor does the flour derived from it give the same type of bread. It has long been known that certain types of flour give a large, well-aerated loaf, generally white in colour, and very palatable, whereas other types give a small loaf which is close in texture, dull in colour, and of a stodgy character. flours are distinguished as strong and weak and are valued with a difference of several shillings a sack in their price. It has been attempted to express this difference between strong and weak wheats by analysis, and from time to time strength has been correlated with high nitrogen content or, what amounts to the same, a high percentage of gluten, or again to a certain ratio of glutenin to gliadin. Though there is a rough parallelism between strength and these factors, it is in no case absolute, so that no one of them could be said to be the cause of strength. Indeed, the solution of the question has been found in quite another direction. Gluten prepared from the strongest flour, when carefully cleaned by repeated washing in distilled water, loses its properties; it has neither ductility nor tenacity and partly dissolves in the water. It acquires these properties again directly small quantities of electrolytes are present, and it is argued, therefore, that the physical properties of gluten are largely controlled by the presence of salts. The analytical study of strong and weak flours, made by Prof. Wood, in following this clue, indicated that the former contained a larger proportion of phosphates: this gave the stimulus to Mr. A. E. Humphries-a practical miller to try the addition of an extract of phosphates from bran to a weak flour, and when this addition proved advantageous in increasing the strength, the effect of adding small quantities of pure phosphoric acid was tried in its turn. A great deal of painstaking research has been necessary for the elaboration of the new technique of improving flour, and it is now commercially possible to impart the qualities of strength to a weak flour, so that it works better in the dough, has an increased water absorption, and gives a larger loaf of lighter texture, which is more easily digested than when untreated. One result of the treatment, which is of the highest national importance, is that it enables a larger proportion of English wheat to be used in the bread mixture. Notwithstanding all that is said by food reformers and agitators in the daily Press, the public do demand a certain degree of lightness and texture in their daily bread, for which the presence of a considerable proportion of strong foreign wheat in the mixture is essential. This is especially the case in the large manufacturing towns in the North any sceptic as to the difference can easily make the experiment of comparing the bread from two kinds of flour at his own table. English wheats as a class yield weak flours, characterised by their excellent flavour. Since they can only be used by the baker to a limited extent they fetch a correspondingly lower price on the market, and to-day are very largely used for household purposes where strength does not matter. The possibility of using a considerably increased percentage of home-grown wheat in the bread mixture is bound to have a favourable effect on the price, the more SO as the small country miller can make use of the local supplies near at hand and will be much less dependent on the supplies of foreign wheat, on which he has to pay freight from the ports of entry where the large milling concerns, with which he is in competition, are usually situated. Chemical science has thus rendered a service which promises to be of the utmost importance to the farmer and the country miller. It is, of course, necessary that a close control should be exercised over the materials allowed to be used as improvers, and nothing but the spraying with soluble electrolytes in minute quantities should be allowed, anything in the nature of loading the flour being strictly prohibited. There is still much prejudice to be overcome against any scientific treatment of wheat, although the baker is allowed free latitude to make the best possible looking loaf from the flour available -an obviously irrational position. Returning to the scientific aspect of the difference between strong and weak flours, it would appear to be yet another instance of those elusive problems in the chemistry of organic colloids such as are concerned in most physiological problems and most of all in that of life itself. The state of aggregation of the colloid and its susceptibility to this and that alteration, owing to the presence of electrolytes of acidic or basic character, as manifested by changes in the physical properties is a general problem which is engaging the attention of many workers. In the case of flour, sufficient has been done to enable great advances to be made on the purely utilitarian side, though their theoretical explanation may be still veiled in obscurity. Although strength in flour has been traced as due to the state of the colloid protein brought about by the presence of a certain proportion of electrolytes, our knowledge is still too indefinite. to enable the farmer to produce a strong wheat by appropriate manurial treatment. The Cambridge School of Plant Breeders has offered good evidence that strength is a factor in the Mendelian sense, and it is considered possible by appropriate selection to obtain a wheat suitable for English soils which will combine strength with the equally important factors of yield and good straw. The efforts of the Home-grown Wheat Committee to encourage the growth of strong wheats in this country have met with only partial success, because, as a rule, strong wheats give poor yields and inferior straw. Much further research is necessary, which can only be done effectively at agricultural stations, such as Rothamsted, or by the agricultural departments of the universities. The composition of the flour is due to the state of maturation of the wheat berry at the time of harvesting, and it will be valuable to know the strength of the wheats produced on the individual plots at Rothamsted with different manurial treatment. However, as shown above, the short cut which the miller is able to take renders him much more independent of the nature of his wheat supply, and it is probable in consequence that the considerable difference in price between strong and weak wheats will disappear to a large extent in the near future, so that the incentive to the farmer to grow strong wheats in this country will disappear. That they can be grown has been proved. SCIEN E. F. ARMSTRONG. THE FOOD OF BRITISH WILD BIRDS. the CIENTIFIC investigations concerning economic importance of our British wild birds are of comparatively recent date, so that at present the sum total of our knowledge is only limited. To arrive at the precise economic value of each of our commoner species is a task of no mean magnitude, and yet it is slowly but surely being forced upon the minds of all thinking people who are concerned with the produce of the land |