296 



NATURE 



[December 28, i<j 



1 1 



Imp'' 

 fa. 



"<1 in th^ir manu- 

 'f blows i* prac- 

 ir<! of nfcr>«i»iiy 



of the iprrim^n* shown exhibited marked tinuoiit 



<di,'<s. hut the bl" ■ ' ' \\ caused them were alt oblique 

 nnd impiniJed at \ .;les. 



(a) Experiments -><.. i»i formed in natural pressure bv 

 means oi an ordinary and a difTurfntiai srrrw press (witd 

 a rubber rnm), f^ivin^; a pressure ranging from 40 to 300 

 tons to the square inch. 



It was found that through a thin layer of sand the 

 pressure was incapable of fracturing the thinnest flint 

 flake*. 



On a hard surface, th»« pressure and resistance being 

 equal, f1al<es were detached from flint nodules showing 

 two bulbs, one at each end of the flake and opposite to 

 each other. 



In the case of a flake detached by percussion, only one 

 bulb occurs. Thcrrforp this fact provides an excellent 

 test for differentiating between man's work and flaking 

 by natural pressure. 



If the under surface on which the flint rests is not 

 sufTiriontly resistant, a flake detached shows only one bulb, 

 which is entirely different from that produced by per- 

 cussion. 



When a suitable flint is carefully placed upon another 

 equally suitable, and pressure applied, a *' hollow-scraper " 

 can be produced showing much finer flaking than that 

 resulting from percussion. 



It is known that the finer flaking on Neolithic imple- 

 ments, such as arrow-heads and " pigmies," is always 

 produced by pressure applied by man. 



.\ large number of specimens was shown to illustrate 

 e.ich experiment described. 



71 



THE MEDICAL WORK OF THE LOCAL 

 GOVERNMENT BOARD. 



"HE report of the medical officer of the Local Govern- 

 ment Board for the year 1910-11 ' has been issued 

 with commendable promptitude. Dr. Newsholme's report, 

 which occupies the first seventy pages of the volume, gives 

 a comprehensive review of the public health in 1910 and 

 of the work of the medical department of the Board, and 

 epitomises some special subjects considered during the year, 

 public vaccination, and the auxiliary scientific investiga- 

 tions carried out for the Board. 



The review of the public health gives some of the more 

 important facts as to the incidence of particular diseases, 

 and a comparison is given graphically for the ten vears 

 1901-10. It is gratifying to find that there has been a 

 decline in the death-rate for all the following : — general 

 death-rate, infant mortality, enteric fever, scarlet fever, 

 diphtheria, puerperal diseases and accidents, and phthisis 

 and tuberculous diseases. Measles alone has not markedly 

 diminished. One of the most striking declines in the 

 death-rate is that of enteric fever, which has diminished 

 from about 16 per 100,000 in 1901 to about 45 in 1910, a 

 percentage decline of 70, representing a saving of nearlv 

 10,000 lives in 1910 compared with 1901, and a financial 

 saving estimated at 1,492,800!. Pulmonarv tuberculosis 

 (phthisis, consumption) was responsible for '38,639 deaths 

 in 1909, still a heavy mortality ; but had the same death- 

 rate existed in this year as in 1871-So the deaths would 

 have been 78,308 : this saving of life represents a financial 

 saving of nearly six millions sterling. Preventive medicine 

 may well be proud of such results as these ! 



The circumstances of the outbreak of plague in Suffolk 

 are discussed, but these have already been dealt with in 

 our pages. 



Of the auxiliary scientific investigations, Dr. Gordon has 

 once more studied the types of streptococci present in the 

 fauces in scarlet fever. He has found that the scarlatinal 

 streptococci are indistinguishable from streptococci present 

 in other disease processes ; this leaves the problem of the 

 etiology of scarlet fever still unsolved. Infantile diarrhoea 

 has been investigated by Dr. C. J. Lewis at Birmingham, 



J Fortieth Annual Report of the Local Government Board, tgto-ii 

 Supplement oontam.ng the Report of the Medical Officer for 1910-11. 



NO. 2200, VOL. 88] 



Dr. S. M. Ro»f at Manchester, Dr. R. A. O'Br • 

 London, and Dr. T. Orr at Shrewsbury. Of d. 

 cat«a, 49-2 per cent, yield non-lactose fermenting orj; 

 from the f icces ; of non-diarrhoea cases, only 19-1 yi' 

 •tmilar organisms, showing a much greater fr<*qu''nr^- 

 non-Iactose fermenters in diarrhoea than in t 

 one type of organism, however, has been 

 suflficient frequenc)' to justify the assumptiun m.u - 

 disease is necessarily or usually attributable to one .'■ 

 the same organism. 



Dr. Andrewes contributes a study of the bacteria pre*- 

 in the air of sewers and drains, a subject previous 

 investigated by him for the Board in 1906-8. In the c.-> 

 of sewers, the dissociation of micro-organisms from ti 

 sewage is very small. In the case of drains, where th- 

 may be much more splashing than in sewers, organ is r 

 dissociated from the sewage may be far more numer<< 

 and may be carried by air currents in large numbers f 

 considerable distances. 



Dr. Inman has studied the secondary infections 

 pulmonary tuberculosis. He considers that in nearly ev- ; 

 case of "open tuberculosis" of the lungs the tubertl 

 bacillus is the predominant infecting agent. 



R. T. !^- ■'— 



THE HEDLEY GOLD FIELD, BRITISH 

 COLUMBIA.' 



'T'HK; mining town of Hedley on the Similkameen Riv' 

 in British Columbia, a little west of the 120: 

 meridian and about twenty miles north of the I'nited Stat' - 

 boundary, is the most important mining camp in thr 

 district, and is of interest owing to the unusual charact. 

 of its ores. The town is situated near the mouth of t 

 Twenty Mile Creek, a canyon from 2500 to 4000 feet d- 

 and with walls sloping at angles of 40°. The first mini: 

 claims were discovered there in 1894, and though m.i: 

 small mineral deposits have been found in the district, th- 

 are only two producing mines, the Nickel Plate and t. 

 Sunnyside Mines, of which the former is the most produc-,, 

 tive gold mine in Canada. 



The country consists of Upper Palaeozoic rocks, doul 

 fully identified as Carboniferous ; they include a lower ser 

 of limestones, quartzites, and argillites, a middle series 

 limestones and quartzites — the Nickle Plate Format 

 and an upper series of tuffs and volcanic breccias — the 

 Mountain Formation. The sedimentary series was invad 

 in early Mesozoic times by intrusions of gabbro and diori^ 

 The ore deposits are unique in America, for they are conta 

 metamorphic deposits containing arsenopyrite as the pr 

 cipal gold-bearing mineral. The ores are developed ale 

 the contacts between the gabbro and diorite with the se 

 mentary deposits. The igneous rocks have metamorphc , 

 the limestones, but have had a comparatively small efffl 

 on the quartzites, argillites, and tuffs. The mineralisat^ 

 is greatest where the contact alteration is greatest, 

 though gold is found in all the sulphides the highest vali 

 occur in the arsenopyrite. The granodiorite has had coa 

 paratively little effect either as a source of metamorphii^ 

 or of ores, and the gabbro has been far more actjve thi 

 the diorite. The gabbro forms the foot-wall or is closf' 

 associated with the ore bodies in the two producing min 

 and in some of the smaller ore deposits. 



After the intrusion of the igneous rocks the field was 

 faulted and fissured ; but neither faults nor fissures are ot 

 much economic importance. The faults were later in dat.- 

 than the ore bodies, and the fissures are filled with barren 

 veins of quartz and calcite, and contain no ore deposits of 

 commercial value. The ores, in fact, do not occur in well- 

 defined lodes, but they grade off imperceptibly into barren 

 country rock. As the ore deposits occur parallel to th 

 bedding planes, it has been suggested that the gold was 

 originally scattered through the sedimentary rock, and has 

 been concentrated by the igneous activity ; this suggestion 

 was all the more natural, as the gold has been found widely 

 distributed through the sedimentary rocks. It is found in 

 them, however, only within the sphere of influence of the 



1 "The Geology and Ore Deposits of Hedley Mining District, BritiA 

 Columbia." By C. Camsell. Canada Department of Mines Geological 

 >iir\ey Branch, Memoir No. a. Pp. 2i8-|-xx plates+S figs+4 map*. 

 (Ottawa, 1910 ) 



