October 28, 19 15] 



NATURE 



?39 



trades. On the other hand, the codes of all the chief 

 European countries, the United States, and India con- 

 tain provisions requiring adequate lighting in 

 factories. 



The results of bad lighting have been studied in 

 detail. A statistical inquiry into the number of acci- 

 dents in various industries in each month of the year 

 points to the conclusion that inadequate lighting is 

 a contributory cause of accidents ; it is significant that 

 in mines the number of fatal accidents in surface work 

 is greater in the winter when there is less daylight 

 available, and the "accident rate" in most industries 

 studied is considerably greater by artificial than by 

 natural illumination. The evidence of witnesses and 

 the statements of the Accident OfTiees Association, 

 which embraces most of the insurance companies 

 interested in the Workman's Compensation Act, sup- 

 ports this view. Specific instances are quoted of the 

 effect of improved lighting in increasing the output 

 and quality of work, and there is a general impression 

 that unsatisfactory lighting is, in various ways, pre- 

 judicial to health. 



The committee recommends that : — 



(i) There should be a statutory provision : — 



(a) Requiring adequate and suitable lighting in 

 general terms in every part of a factory and work- 

 shop, and 



{h) Giving power to the Secretary of State to make 

 Orders defining adequate and suitable illumination for 

 factories and workshops or for any parts thereof or 

 for any processes carried on therein. 



It is pointed out that "adequate lighting" should 

 comply with the following requirements : — 



(a) Adequacy. 



(&) A reasonable degree of constancy and uniformity 

 of illumination over the necessary area of work. 



(r) The placing or shading of lamps so that the 

 light from them does not fall directly in the eyes of 

 an operator when engaged on his work, or when 

 looking horizontally across the workroom. 



{A) The placing of lights so as to avoid the casting 

 of extraneous shadows on the work. 



Certain recommendations are also made regarding 

 the amount of illumination necessary in the working 

 areas of factories, in foundries, dangerous parts of 

 wavs and open spaces, etc., and there is a special 

 recommendation providing for exemption in special 

 cases. These values, which range from 005-0-4 ft.- 

 candle, are prescribed in the interests of safety and 

 convenience, and without prejudice to the special 

 illumination required for the carrying on of work. 

 At present the committee is not prepared to recom- 

 mend standards of illumination for various classes of 

 work which require further investigation. 



In the appendices, the measurements of illumination 

 in various classes of factories are tabulated in such 

 a way as to show the average values existing, and it 

 is shown that the above values, which are suggested 

 as a practical legal minimum, impose no hardship. 

 Many manufacturers would prefer to provide sub- 

 stantially higher values, and these recommendations 

 would be mainly instrumental in improving the 

 illumination in out-of-date factories which have 

 lagged behind the general advance. Besides carrying 

 out tests of the artificial lighting in factories in terms 

 of foot-candles, the committee has also accumulated 

 a considerable amount of information regarding the 

 natural illumination. This is expressed in terms of 

 the "daylight factor" {i.e. the relation between the 

 illumination inside a workroom and the total un- 

 restricted illumination out of doors). The experiments 

 at the National Physical Laboratory illustrate the con- 

 nection existing between the amount of illumination 

 required and the character of the material illuminated, 

 which may be expressed thus : — 

 NO. 2400, VOL. 96] 



Coefficient of reflection of material x illumination 

 necessary = constant. 



Other experiments bear on the relative merits of 

 direct and indirect lighting for certain classes of work. 

 The visibility of detail consisting of fabrics, embossed 

 papers, engraved metal, etc., demands unidirectional 

 illumination, and the ability to distinguish such 

 detad is, for the same illumination, greater by direct 

 than by indirect light. 



An enterprising step in connection with this report 

 is the issue of a short memorandum summarising its 

 aims and conclusions, and pointing out the special 

 interest attaching to the report at the present time, 

 when so many factories are working overtime and 

 preparations are being made for the period of the year 

 when artificial lighting is mainly required. 



THE TURQUOISE.^ 



DIKING several years, whilst a curator in the 

 United States National Museum, Dr. Pogue 

 collected all the available information respecting this- 

 familiar gem-mineral, visiting for this purpose the 

 principal museums and libraries of America and 

 Europe. The result is an elaborate compilation with 

 numerous footnotes giving references to the scattered 

 literature of the subject. Being an exhaustive treatise 

 on turquoise, although containing practically no- 

 original matter, it would have been more accessible 

 and convenient for reference if it had been issued as 

 a separate octavo volume, rather than being buried in 

 the large quarto volumes of an academy publication. 



The various aspects under which the subject is 

 treated are indicated in the title. The section on 

 geology contains a detailed account of the occurrence 

 of the mineral at all its known localities, particularly 

 those in Persia, the Sinai Peninsula, and the south- 

 western portion of the United States. The States of 

 New Mexico, Arizona, California, Nevada, and 

 Colorado, where many ancient workings are known, 

 have recently become important sources of the 

 mineral, producing stones rivalling the Persian in 

 quality. A useful table is given stating the enclosing 

 rocks (mainly igneous rocks, and especially trachyte), 

 the associated minerals (usually limonite, kaolin, and 

 sericite), etc., for the more important turquoise 

 occurrences. The mode or modes of origin of the 

 mineral are discussed, and the general conclusion 

 drawn that it has been formed by the percolation of 

 surface waters through aluminous rocks containing 

 apatite and disseminated copper minerals. An 

 attempt is made to disentangle the confusion asso- 

 ciated with the name " chalchihuitl" of the American 

 aborigines. Although the early Spaniards confused 

 several green stones under this name, it would appear 

 that the Indians of the south-western States referred 

 to turquoise, whilst in Mexico the material so-called 

 was mainly jade. A detailed bibliography and a good 

 index complete the work. The plates are, for the 

 most part, devoted to representations of ancient orna- 

 ments set with turquoises. L. J. S. 



PURPOSEFUL FORAMINIFERS. 



MR. EDWARD HERON-ALLEN is to be con- 

 gratulated on the interesting results which are 

 rewarding his assiduous study of the Foraminifera, 

 His latest contribution (Phil. Trans., June, 1915) deals 

 with the processes of reproduction and of shell-making. 

 In addition to the production of zoospores observed 



1 "The Turqnoise. A Study of its History, Mineralogy, Geology. Ethno- 

 logy, Archaeology. Mythology, Folklore, and Technologjj." By J. E. Pogue. 

 Memoirs of the National Academy of Sciences, Washington, D.C. , 1915, 

 vol. xii., part ii., 3rd Memoir, pp. 162, za plates. 



