i68 



SCIENCE. 



[Vol. XII. No. 296 



cutting, but the crumbling of banks to a large extent is caused 

 by the dissolving-power of water. Loam, clay, and silt as a rule 

 largely constitute the banks of rivers. Water coming into contact 

 with loam at a point e will destroy its cohesion, and carry it away. 

 The water falling from level {e d) \.o a b eats into the bank as far 

 as/, and the whole body (J e g), deprived of its support, will 

 tumble down into the river as soon as it is sufficiently heavy to 

 overcome the cohesion along g f ; this irrespective of any sedi- 

 ment being mixed with the water, as pure water will destroy the 

 cohesion of those materials in exactly the same way as water loaded 

 with sediment. 



The same effect is produced by frost. If bank-material saturated 

 with water freezes up, its cohesion is destroyed. The spring freshets 

 will carry it away. 



Another instance of this kind is a bank consisting of layers rest- 

 ing on an inclined clay seam. When for some reason the seam 

 becomes exposed to water, this will moisten its surface and trans- 

 form it into a slippery mass, thus causing the overlying strata to 

 slide into the river. 



Therefore, suppose the head waters of all the tributaries of the 

 Mississippi to furnish an entirely clear supply of water. It enters 

 the river-channel. Immediately it picks up such sediment as its 

 velocity enables it to carry. More sediment is added by the causes 

 presented, — the old condition ! 



There are other remedies of long-established repute, which, if 

 not by the same constructions, in principle certainly, will be just as 

 practical here as anywhere else. 



" The prime end to be sought," so Major Powell correctly puts 

 it, " in order to prevent destructive floods, is to prevent the chok- 

 ing of the channel ; " and again, " The real problem is to relieve 

 the river of its excess of sediment." In these views engineers will 

 ifully concur. The letter touches upon one of these remedies : 

 ^' Much of a coarser sediment is left to add to the geological 

 growth of the region, while vast quantities pass on to the sea." 

 The end to be sought, then, is to reverse this condition, and make 

 the vast quantities add to the geological growth of the region. 

 This can be accomplished by fixing, protecting, and in that way 

 solidifying, large deposits which are now in constant migration, 

 and preventing their being transformed again into floating sediment. 

 To this end force the river into a channel, which removes the de- 

 posits from the current. 



The sediment contributed by the tributaries now is only a trifle 

 as compared with the amount centuries have accumulated in the 

 beds of the Missouri and Mississippi. To make these enormous 

 quantities terra firma is more effective than to clean the mountain 

 waters, because the effect will be felt right there where the work is 

 done, and at once. 



Another means of making the sediment add to the geological 

 growth of the region is this : Create a strip of ' dead ' water on both 

 banks all along the entire extent of the rivers in open and direct 

 connection with the current. There will be a constant exchange 

 of water between the current, where the water is loaded with sedi- 

 ment, and these bodies of standing water; and whatever water 

 irom the current gets into this strip will deposit its sediment. 

 Then it returns into the river, is reloaded with detritus, and. re- 

 enters the strip of standing water. Thus a destructive agency will 

 be turned into a useful tool, carrying along sediment to add to the 

 geological growth of the region. In course of time this strip will 

 be completely filled, and then the water will not only flow in a con- 

 centrated channel, but there will also have been formed a terrace 

 at the foot of the old bank, which protects it. This is the really ef- 

 fective settling-basin, and the thousands of miles of river-banks are 

 the places where they must be constructed, because they do the 

 work right on the spot where it is needed. 



Julius Meyer, C.E. 



Cleveland, O., Sept. i8. 



Chalchiuitl : A Note on the Jadeite Discussion. 



The jadeite discussion is evidently not yet terminated. In the 

 American A?itkropo!ogisi for July, 1888, Dr. A. B. Meyer of Dres- 

 den maintains his position " that the nephrite (jadeite) question is 

 not an ethnologic problem," the mineral occurring wherever the 

 artefacts from it are found ; while at the recent meeting of the 



American Association for the Advancement of Science, August, 

 1888, Prof. F. W. Putnam of Cambridge reiterated his belief, al- 

 ready expressed in the reports of the Peabody Museum, that the 

 specimens of jadeite from Mexico and Central America were origi- 

 nally brought from Asia. 



Jade first became known to modern Europeans by the specimens 

 brought from Mexico, as the origin of the name attests (Spanish, 

 piedra de ijada, so called from its supposed virtues in colic, mal de 

 ijada), and therefore the references to it in the early writers on 

 Mexico merit special attention. These have been partly collated 

 by E. G. Squier, in his ' Observations on a Collection of Chalchi- 

 huitls' {Annals of the Lyceum of Natural History, New York, 

 1869), and later by Professor Fischer in his well-known volume 

 ' Nephrit und Jadeit.' In verifying these quotations, I find that 

 some important authorities have been altogether omitted, and oth- 

 ers only partially reported. No direct reference is made to the 

 Codex Mendoza ; and Squier omits some of the most important 

 observations of Sahagun, to wit, those referring to the provenance 

 of these minerals, — the very point which, in the present stage of 

 the question, we wish light upon. The practical bearing of this 

 point will be readily appreciated when I add that the statement was 

 made at the meeting of the American Association in August, that 

 last wmter an expert was sent to Mexico at considerable expense 

 for the sole purpose of discovering the locality of the jadeite, but 

 his search was vain. 



The Nahuatl (Mexican) name for jadeite is chalchiuitl. This 

 appears to have been applied to any greenish, partially transparent 

 stone capable of receiving a handsome polish. All such were 

 highly esteemed. Specific distinctions were established between 

 such precious minerals by descriptive adjectives, as follows: — 



Jztac chalchiuitl, white chalchiuitl ; of a fine green, quite trans- 

 parent, without stripes or stains. 



Quetzal chalchiuitl, precious chalchiuitl ; white, much transpar- 

 ency, with a slight greenish tinge, somewhat like a jasper. 



Tlilayotic, literally, ' of a blackish watery color ; ' with mingled 

 shades of green and black, partially transparent (chlormelanite ?). 



Tolteca-istli, literally ' Toltec knife,' or ' Toltec obsidian ; ' of a 

 clear, translucent green, and ' very beautiful.' 



These are the descriptions of Bernardino de Sahagun {Historia 

 de la Nueva Espaha, Lib. XI. cap. 8), probably the source of all 

 other writers upon this subject. He is not very exact as to the 

 localities in which they were found by the natives. The first-men- 

 tioned, however, the white chalchiuitl, he states was obtained from 

 quarries in the vicinity of Tecalco. This town, which I do not find 

 on late maps, was in the state of Puebla, and it may be the modern 

 Tecali mentioned by Orozco y Berra in that state (Geografia de las 

 Lenguas Indijenas de Mejico, p. 211). It would be worth while 

 searching in that vicinity. 



With reference to the last-mentioned variety, the Toltec stone, 

 Sahagun makes a noteworthy remark, not quoted by Squier, which, 

 so far as it goes, is certainly in favor of the view that this valued 

 variety was not from any deposit known to the natives. This beau- 

 tiful species of chalchiuitl, he says, did at one time exist in this 

 country (New Spain), "and does yet, as is prcved by the pieces ob- 

 tained from the ancient edifices." In other words, no deposit was 

 known to the natives of his day, and such fragments as they pos- 

 sessed were exhumed from the ruins of the ancient cities. 



The Codex Mendoza is a copy of the tribute-roll of the ancient 

 Mexican Empire (published in LORD Kingsborough's Mexican 

 Antiquities). It defines the tax from each district, naming the 

 cities. Strings of chalchiuitl are mentioned as part of the tribute 

 from a number of localities, and refer evidently to small rounded 

 pieces used as beads, and obtained from the sands of streams. 

 Only from one district are large pieces of chalchiuitl demanded. 

 These, three in number each year, were required from Tototepec, 

 Chinantlan, and other towns situate in the present state of Oaxaca, 

 and principally in the department of Vilalta (Zoochiia). Miihlen- 

 pfordt describes this region as mountainous and wild, inhabited by 

 the Mixe Indians and the Chinantecas {Schilderung der Republik 

 Mejico, Bd. II. s. 213, 214). This is the spot to which the explorer 

 should penetrate if he would discover the locality of the large pieces 

 of Mexican jadeite. D. G. Brinton. 



Media, Penn., Sept. 28. 



