Jan. 31, 1889] 



NATURE 



329 



feature is the great and almost interminable palm forests, which, 

 singularly enough, in the Chaco are a sure indication of marshy 

 lands subject to inundation, although in the province of Entre 

 Rios, and other parts of the world, they are the exact contrary. 

 On the northern and eastern borders of the River Bermejo the 

 Central Chaco rises sensibly, as if to form a barrier to the 

 waters of that river in their easterly progress. The Chaco 

 Austral of the Argentine is the most favoured in natural riches 

 of the three great sections. Its surface rises gradually from the 

 Parana River, and is intersected by several small streams, which 

 are even now useful as a means of water-carriage to the many 

 colonists settled along their courses ; after rising thus up to the 

 parallel of 25° 40' S., the ground dips towards the valley of the 

 San Francisco, sending its waters with those of that river to the 

 Bermejo, sometimes in untimely floods. This depression extends 

 across the Central into the Paraguayan Chaco, taking in the 

 sections of the two rivers that are subject to yearly overflows 

 between long. 61" and 62" W. of Greenwich, thus making a 

 point of analogy between the two. The Austral is favoured with 

 extensive primeval forests, notably that on the north-western 

 border extending into Salta and covering a superficies of many 

 hundreds of miles, quite unexplored, and sometimes designated 

 ' by the name of " impenetrable." The principal water-courses 

 of these territories are the Pilcomayo and Bermejo, which are 

 undoubtedly destined to become highways of commerce. The 

 waters of these rivers differ in colour, those of the Pilcomayo 

 being dark and sometimes brownish, and those of the Bermejo 

 red, as its name indicates ; both are long, narrow, and tortuous, 

 as are most of the interior rivers of the La Plata system ; both 

 run in a general south-east direction, preserving a remarkable 

 parallelism throughout their entire course, running distant from 

 each other as nearly as possible 180 miles. Neither of these 

 streams receives tributaries of any kind over the greater part of 

 their course, and their waters are consequently subjected to a 

 great and constant drain from evaporation, in a climate whose 

 average temperature is 80° F., as well as from absorption by the 

 deep alluvial covering overlying the compact argillaceous bed, 

 which is a geological characteristic of the whole Chaco subsoil. 

 The impermeability of this bed probably arrests the effect of 

 absorption, and in a great measure accounts for the non-diminu- 

 tion of the wealth of waters delivered into the Paraguay ; such a 

 geological formation may also account for the saline properties 

 of the waters found in the Chaco, wherever wells have been 

 made. The density of the Bermejo water is greater than that of 

 the Pilcomayo ; the amount of sediment it brings down is 

 enormous, and it is deposited with such extraordinary rapidity 

 that it cannot but be considered a peculiarly strong feature of 

 the mechanical work of this river, by which its geological forma- 

 tions are rapidly made, and, indeed, unmade as well ; this 

 swift precipitation of its detritus, which it replaces by an increas- 

 ing abrasion of the banks, may be caused, to some extent, by 

 the quantity of salt contained in its water. This constant pre- 

 cipitation goes on in the Bermejo, even when at its height, and 

 when in the exercise of its greatest carrying power, with a speed 

 quite equal to the square of its normal current ; a fact which 

 would seem to say that its currents are swifter on the surface 

 than over its bed. Captain Page has sten this river eat away 

 an entire point of land, and, by way of compensation, deposit, 

 just a turning below, an amount of delritus sufficient to form a 

 similar promontory, which, in one season of low water, became 

 covered with a thick and luxuriant grovvlh of red willow. The 

 Pilcomayo — the Piscumayu, as it is called in the Quichua tongue, 

 signifying Bird River — is to a great extent unknown. The sec- 

 tion that is quite unknown, and that is surrounded by a certain 

 mythical halo which it will be a geographical triumph to dispel, 

 is that comprised between long. 61° and 62° W., and the paral- 

 lels of 22'' and 23^ S. ; the river at this point was said, by 

 theorists who forgot to account for its reappearance inmiediately 

 below, to disappear altogether. Captain Page then gave an his- 

 torical sketch of the various expeditions which have explored 

 the Gran Chaco, concluding with an account of an expedition 

 in a steamer up the River Bermejo, which he himself led, 

 amidst many dangers from banks, and snags, and wrecks, as well 

 as from the widespread flood that suddenly overtook him. 



With the first number for 1889 a useful modification has been 

 introduced into Pdermann' s Mitteilungen. For the last few 

 years, in addition to the classified list of geographical publica- 

 tions each month, there has been a separately paged supplement 

 containing critical analyses of the more important works. These 

 were often carried to such length that many of the notices were 



from six to twelve months behind date. Now, the two lists are 

 to be amalgamated, the notices are to be greatly reduced in 

 length, and thus it is hoped that new works in the various 

 departments of geography will be promptly made known to the 

 readers of the Mitteilungen. In the first number of this year is 

 an important paper on valleys of erosion, by Dr. V. Hilber, The 

 paper consists mainly of an analysis of the nine theories that 

 have been advanced to account for the formation of such valleys. 

 The author himself favours the regression theory, according to 

 which valleys have mostly been formed by retrogression, through 

 the erosion of a river from its mouth backwards. 



Captain van GI'.le, the explorer of the Mobangi-WeIle,was to 

 leave Antwerp on the 29th for the Congo, to undertake a special 

 mission. Me is accompanied by Lieut. Le Marinel, Lieut. De 

 Reohter, and M. Ferd. Meunier, as naturalist. 



M. Maurel, who has explored French Guiana, recently 

 described the results of his observations and investigations to the 

 Creographical Society of Toulouse. From the orographical 

 point of view, he stated, French Guiana comprises four zones, 

 rising in stages to the Tumac Humac Mountains. The first 

 consists of a broad band of alluvial country. The second zone is 

 hilly, covered throughout by a series of hillocks and bluffs, not 

 exceeding 650 feet in height, and frequently separated by 

 shallow valleys. The third zone M. Maurel describes as 

 mountainous, with an irregular surface, abrupt slopes, and 

 deep valleys. The Tumac Humac chain constitutes the fourth 

 zone, and it rises by a series of gradations to a height of about 

 4000 feet. M. Maurel has collected a number of flint objects, 

 which he believes belonged to a pre-historic race that must have 

 inhabited the country before the alluvial period. He accounts 

 for the present formation of Guiana by two long-separated 

 volcanic outbursts, acted on subsequently by a large river, 

 which he believes gave origin to the deposits of the first zone. 



Mr. J. Y. Buchanan, Prof. A. H. Keane, and Mr. 

 J. T. Wills, are candidates for the Lectureship in Geography 

 at Cambridge, vacant by the resignation of Dr. Guillemard. 



The Russian Geographical Society has just brought out, as 

 an appendix to the nineteenth volume of its Memoirs, an 

 atlas containing all the measurements made by A, Kaulbars in 

 the delta of the Amu-daria. These measurements, which will 

 be invaluable to those who may hereafter study the changes 

 going on in the delta of the great Central Asian river, could not 

 be embodied in M. Kaulbars's capital work " The Old Beds of 

 the Amu,'' published by the Society in 1887. Now they are 

 given partly in the atlas (on the scale of i : 1,500,000), and in 

 lull in the text which accompanies it. 



THE PRESENT STATE OF SEISMOLOGY IN 

 ITALY.^ 



nPHIS group of papers affords the reader a very fair means of 

 -*- forming a mental estimate of what Italy has been doing 

 to study her earthquakes during the last year or eighteen 

 months. 



Signor E. Brassart, for some years the Mechanical Constructor 

 of the Central Office of Meteorology and Geodynamics, has pro- 

 duced a seismoscope in which a small slug perched on a thin 

 cclumn was overturned by the earthquake, and fell into an 

 umbrella-like balance-pan surrounding the peg. In this way 

 the direction of the shock was supposed to be indicated by the 



' "Sismoscopi o Avvisatori Sismici," Ermanno Brassart. _ "I Sismomctri 

 Presentemente in Uso nel Giappone." esaminati e descrltti da Ermanno 

 Brassart; con proposta di un Sismometro di Nuovo Modello. "II .Sismo- 

 metrograph a Tre Compmenti con Una Sola Massa Staiionaria," Nota di 

 Ermanno Brassart. '"Sulla Slstemazione delle Osservaz.oni Geodinamiche 

 Regolari," del Prof. Giulio Grablovitz. " Relazione della Sottocomniissione 

 Incaricata di Stiidiare alcune Proposte per I'Ordinamento del Servizio Geo- 

 dinamico nell' Italia Meridionale e nelle Isole," del Prof. T. Tarame i. 

 " Relazione alia R. Sottocommissione Geodinamica sulla Distnbuzione dells 

 Aree Sisniiche nell' Italia Superiore e Media," del Prof. T. Taramelh. " 11 

 Terremoto nel Vallo Cosentino del 3 Dicembre, 1887.'; Studio del Dott. 

 Giovanni Agamennone.— All these papers are published in the Annah deU 

 Ufficio di Meteorologia e di Geodinamica, vol. viii. Parte 4, Anno i836. 

 (Kome, 1888.) . X, . ,^ . 



" Alcuni Risultati di uno Studio sul Terremoto Ligure del 23 Febbraio, 

 1887," Nota di T. Taramelli e G. Mercalli, Rendiconti d. R. Accad. dei 

 Lincei, vol. iv. fasc. i. (Roma, i838.) 



