May 19. 1898] 



NATURE 



51 



OUR BOOK SHELF. 

 An Elementary Course of Physics. Edited by Rev. J. 



C. P. Aldous, M.A. Pp. 862 + vi. (London : Mac- 



millan and Co., Ltd., 1898.) 

 In this book an attempt is made to give a modern and 

 practical course of natural philosophy in a compendious 

 form, and it may be stated at once that the effort is a 

 most successful one. It is the joint work of the editor, 

 who is chief instructor on H.M.S. Britannia, Mr. W. D. 

 Eggar, and Prof. F. R. Barrell. The editor is himself 

 responsible for the sections dealing with mechanics, 

 properties of matter, hydrostatics, and heat, in which the 

 readers are provided with " a groundwork of theoretical 

 knowledge which may enable them to understand and 

 use the simple processes of the kinetic method, to express 

 themselves with accuracy when necessary, and to deal 

 with simple mechanical problems." Wave-motion, 

 sound, and light are admirably treated by Mr. Eggar, 

 while Prof. Barrell's contribution deals with the subjects 

 of magnetism and electricity. 



The treatment of the various subjects is most lucid and 

 thorough, and is evidently based on an intimate ac- 

 quaintance with the requirements of students. Great 

 pains have been taken to avoid looseness of statement ; 

 and the fact that some of the sections have had the 

 advantage of the criticisms and suggestions of Lord 

 Kelvin, Lord Rayleigh, and others, makes it a trust- 

 worthy book of reference. Where everything is so well 

 done it is difficult to select points for special mention, 

 but it may be remarked that examples drawn from naval 

 sources form a notable and valuable feature, and graphical 

 methods of representing experimental results are largely 

 utilised and encouraged. The generous supply of illus- 

 trations, which number neafly six hundred, and not one 

 that fails to serve a useful purpose, enhances the value 

 of the book, and will make it acceptable to a wider circle 

 of readers than that comprised by students following a 

 specified curriculum. The book is of convenient size, 

 and is printed in very clear type ; we believe it is destined 

 to take a high place in our schools and colleges. 

 L'Alj(erie. Le Sol et les Habitants, &^c. Par J. A. 



Battandier et L. Trabut. Pp. viii -f- 360. ("Paris : 



Bailli^re et fils, 1898.) 

 This little volume is one of a class of books which is 

 much better represented abroad than in this country — 

 one, that is, in which a complete picture is given of a 

 limited part of the earth's surface, under the varied 

 aspects which make up its geography in the widest sense 

 of the term. It is written on a scientific plan, the broad 

 physical features of the country being taken as the basis 

 of the whole description. In Algeria the authors dis- 

 tinguish three main zones, the Tell (or cultivable region), 

 the Steppe, and the Sahara, holding that the plateaux, 

 which some writers have made into a separate division, 

 do not form a natural region, but fall within the Tell or 

 the Steppe according to the amount of rain which falls. 

 The determining factor, indeed, in the geography of the 

 whole region, is the preponderance of the moist rain- 

 bearing winds from the north-west, or of the parching 

 desert winds from the south and south-east. Each of 

 the zones is in turn described, special attention being 

 given to their natural resources ; and the fact that for 

 over twenty years the authors have traversed the country 

 in the prosecution of their botanical researches, enables 

 them to speak with the accurate knowledge which can 

 only be acquired at first hand. The inhabitants, the 

 fauna and the geology of Algeria are also sketched in 

 outline, so that we have in small compass a useful sum- 

 mary of all that is known of the country. The general 

 conclusion arrived at is that Algeria is capable of sup- 

 porting a large population, and that, in spite of the slow 

 modification the climate has undergone since the dawn 

 of history, cultivation will still be possible for many 

 centuries to come. 



NO. 1490, VOL. 58] 



LETTERS TO THE EDITOR 

 [The Editor does uol hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither (an he undeitake 

 to return, or to cove^p-nd with the writers of, rejected 

 manuscnpis intended f',ir this or any olhei part of Natuuk. 

 No notice is taken of anonymous coinmuifcinoiis.] 



Electric Light Wires as Telephonic Circuits. 



I WISH to put on record the following method of using 



electric lighting wires as telephonic circuit.s. I was requested 



sonic time ago to try to localise a fault in an electric light main, 



by means of a certain form of inductor used in conjunction with 



a telephone but not connected to the main. While using it, it 



occurred to me that probably the main might be used instead of 



a telephone wire. My first experiments were not productive 



of good results, as a small fraction of the Company's current 



passed continuously through the telephone. In October 1897, I 



i placed .^j microfarad condensers in my telephone circuit at each 



I end ; these stopped the current, but in no way reduced the 



j telephonic effects. If the note given out by virtue of the 



I rotation of the armature of the dynamo is great, it can be very 



' greatly reduced by placing an inductively wound resistance in 



the circuit. 



The resistance does not appear to modify the telephonic 

 effects in any marked degree. This probably arises from the 

 fact that the E. M.F. due to the secondary coil of the telephone 

 transmitter is high. The experiment was successfully made 

 over two miles of a main which was carrying the full load 

 used in lighting the town. F. J. Jkrvis-Smith. 



Oxford, May 16. 



Sub-Oceanic Terraces and River Channels off the 

 Coast of Spain and Portugal. 



Will you allow me once more to briefly describe in advance 

 the physical features under the Atlantic off the coast of Spain 

 and Portugal, continuous with those opposite the coasts of the 

 British Isles and the Bay of Biscay, already reported in your 

 columns (Nature, March 24 and April 21) ? 



The great escarpment already described as descending into 

 deep waters from the margin of the British-Continental plat- 

 form is still traceable southwards along the coast of Portugal 

 from Cape Finisterre as far at least as the mouth of the Tagus 

 estuary, where it appears to begin to broaden out and merge 

 into a generally rapid slope — or probably a succession of ter- 

 races. The breadth of the platform along this coast averages 

 only 30 to 40 miles from the shore, and its margin very nearly 

 follows the 200-fathom contour ; but here the descent to the 

 looo-fathom contour is steep, though seldom precipitous, and 

 is varied by numerous bays and headlands. Owing to the in- 

 sufficiency of the soundings, especially off Vigo Bay, the 

 definition of the caiions, or old river channels, is scarcely as 

 clear as in the region further north. Still, I have been able to 

 determine several with a great degree of certainty, such as those 

 formerly continuous with the rivers Padron, Lima, Douro, and 

 Tagus. There are also a few which cannot apparently be 

 followed to their sources in the present land, such as one of 

 special depth and precipitancy in lat. 40° 31' N., distant about 

 40 miles off the coast of Portugal at Barra Nova. The con- 

 tinuation of these features to the Straits of Gibraltar and into 

 the Mediterranean remains for future investigation 



20 Arundel Gardens, W., May 16. Edward Hull. 



Bacteria on an Ancient Bronze Implement. 



Mr. Nicholson probably refers to what is known to archae- 

 ologists as "bronze cancroid." 



In the last number of the Journal of the Royal Society of 

 Antiquaries of Ireland, March 31, this subject is referred to 

 under the name of " Ulcerative Disease of Bronze or ' Bronze 

 Cancroid,'" by Dr. William Frazer. 



As manj readers of Nature interested in bacteria may not 

 be able to conveniently refer to this journal, the following 

 points brought forward by the author will be read with interest. 

 He says, "all objects of antiquity fabricated from metallic 

 copper, and its important alloy made by adding tin in certain 

 proportions, are liable to be attacked by this destructive 



