Ma^ch 28, 1 901] 



NATURE 



M 



The remarkable subsidences which have often occurred in 

 and around the town of North wich, in Cheshire, form the subject 

 of a paper by Mr. T. Ward, recently issued by the Institution 

 of Mining Engineers. The subsidences are chiefly due to 

 mining in the Upper Bed of rock-salt, and the too rapid removal 

 of brine by means of modern pumps. In a natural condition 

 the water in or on tlie salt-beds becomes saturated with salt 

 and then ceases to dissolve it, but now the brine is continually 

 pumped up in" immense quantities, and the fresh water which 

 flows to take its place dissolves the salt pillars which have 

 supported the roof and overlying strata, with the result that 

 there is a depression towards each pumping centre. In almost 

 every case the mines in the Upper Bed of rock-salt are destroyed 

 by water rapidly eroding the salt pillars in this way. Another 

 cause of subsidence is the pumping of brine from off the rock- 

 head, that is, the surface of the Upper Bed of rock-salt. These 

 are by far the most serious and widespread, and it is from them 

 that the town of Northwich suffers so much damage. Owing 

 to the subsidences, which show themselves first by small cracks 

 in the buildings, and in doors and windows refusing to shut, a 

 system of framework buildings has been allowed, so that when 



a building sinks it can be lifted by screw-jacks and put back to 

 its original position. By degrees the town is becoming one of 

 framework buildings, and will, for England, be unique in this 

 respect. The accompanying illustration, which we are enabled 

 to give from Mr. Ward's paper, shows a subsiding house in a 

 street at Northwich. 



We learn from the Scientific American that Mr. Edison has 

 recently taken out a patent for a method of obtaining permanent 

 phonographic records. The wax cylinder on which the im- 

 pressions due to the speech have been made in the usual way is 

 first coated with an extremely thin layer of gold ; this is effected 

 by revolving the cylinder in a vacuum between two gold 

 electrodes between which a vacuum discharge is passing. This 

 thin layer of gold is backed up with copper by electro-deposition 

 and the wax is removed, we imagine by melting it off. Upon 

 the copper matrix thus obtained a deposit of silver is thrown 

 down electrolytically, and when this is of sufficient thickness the 

 copper is dissolved off. The remaining silver deposit will 

 retain the thin layer of gold and will be an exact reproduction 

 of the original wax record, but one much more capable of stand- 

 ing repeated use. The value of the invention depends obviously 



NO. 1639, VOL. 63] 



on the fidelity with which the final silver record reproduces the 

 original sounds ; if the reproduction is accurate the process is a 

 very useful one, since a phonographic record which is at once 

 faithful and permanent should be of considerable value for 

 historical purposes. 



In the February number of the Victorian Naturalist Mr. 

 A. J. North continues his observations on the geographical 

 distribution of Australian birds. 



A RECENT issue of the Bulletin of the Illinois State Laboratory 

 of Natural History (vol. v. art. 12) deals with the local fauna of 

 leeches (Hirudinea), of which several new forms are described. 

 The occurrence of certain European species is especially note- 

 worthy. Several beautiful plates illustrate the morphology of 

 some of the more remarkable types. 



In its Report for the past year the Oxfordshire Natural 

 History Society and Field Club sets an excellent example to 

 association? of a similar nature by the publication of the first 

 instalment of a local fauna. The group dealt with on the pre- 

 sent occasion is the Hymenoptera Aculeata, comprising ants, 

 wasps and bees. The local list is also 

 issued in a separate form, printed only on 

 one side of the paper for cutting up to 

 label collections. 



Dr. L. Stejneger sends us a copy of 

 a paper on the North American wheatears 

 {P. U.S. Mus. xxiii. p. 473), in which it is 

 shown that a race of these birds habitually 

 breed in North America. From the differ- 

 entiation of this Greenland race the author 

 thinks we are justified in inferring that the 

 Greenland-Iceland-England line of migra- 

 tion must be considerably older than the 

 Alaska-Tchuktchi-Udski route, since it 

 has resulted in the establishment of the 

 local variety of the wheatear forming the 

 subject of this communication. 



Two papers in the March issue of the 

 Quarterly Journal of Microscopical Science 

 record important advances in our know- 

 ledge of the lancelets. In the first Dr. 

 A. Willey describes a new subgeneric type 

 of these primitive chordates from the Orissa 

 coast, under the name of Branchiostoma (Dolichorhynchtis) 

 indicus. The distinctive characteristic is the anterior prolonga- 

 tion of the notochord and head- fin ; so that this form is 

 exactly the opposite of Heteropleuron (Asytntnetron) lucayanum, 

 in which these parts are extended in the other direction. In 

 the second communication Prof. W. B. Benham describes the 

 New Zealand lancelet as Heteropleuron hectori. It may be 

 mentioned that, according to modern ideas of nomenclature, the 

 name of the first subgenus of the typical group should be 

 Branchiostoma, and not Amphioxus, which is a synonym. 



To the same journal Mr. R. I. Pocock contributes an im- 

 portant memoir on the Scottish Silurian scorpion, with a figure 

 of the specimen discovered in Lanarkshire in 1883. This the 

 author makes the type of a new species, Palaeophonus htcnteri. 

 As the result of his investigations, Mr. Pocock concludes that 

 Palaeophonus apparently occupies a position intermediate be- 

 tween the king-crabs (Limulus) and the Palsozoic Eurypterids, 

 on the one hand, and modern scorpions on the other, although, 

 if anything, rather nearer the former than the latter. The 

 Scotch species thus supplies a few more links to the chain of 

 evidence connecting the line of descent of the modern terrestrial 

 scorpions from marine ancestors more allied to the king-crabs. 



