282 



NATURE 



[December 13, 1917 



The concluding- chapter is devoted to the g-eo- 

 log-ical history of the " banket " and to the much- 

 discussed question of the mode of orig-in of its 

 gold. The original deposition of the con- 

 glomerates has been variously assigned to lacus- 

 trine, fluviatile, deltaic, and marine agencies. A 

 marine origin has been most g-enerally favoured, 

 and is here supported. With regard to the 

 genesis of the gold, the well-known "placer," 

 "infiltration," and "precipitation" theories are 

 outlined. The last, in agreement with prevailing- 

 opinion, is regarded as untenable. The author, 

 at one time an advocate of the second theory, is 

 now led to adopt that modification of the first to 

 which so many who have followed the controversy 

 have been attracted of late years, viz. that the 

 "bankets" are ancient and highly modified 

 " placers " in which the originally detrital gold 

 has been dissolved by high-temperature solutions 

 and redeposited. This has entailed the loss of 

 its detrital form, and the assumption of the crystal- 

 lised state and the association with secondary 

 minerals which it now exhibits. There is much 

 to be said for this view, since it reconciles the 

 facts which point to a "placer " origin with those 

 which prove deposition from solution, and from 

 which " infiltration " of the gold from outside has 

 been erroneously inferred. 



The author is to be congratulated upon his 

 remarkably fine series of illustrations. The collec- 

 tion and preparation of the material for these must 

 have involved the expenditure of much time and 

 labour. They add greatly to the value and interest 

 of tbe volume. C. G. C. 



MUNICIPAL ENGINEERING. 

 Municipal Engineering Practice. By A. Prescott 

 Folwell. Pp. xi + 422. (New York: John 

 Wiley and Sons, Inc. ; London : Chapman and 

 Hall, Ltd., 1916.) Price i6s. 6d. net. 

 'T'HE author defines the purpose of municipal 

 -■- engineering to be the planning, construct- 

 ing", and maintaining of the publicly owned 

 features and utilities of a city. He points out that 

 its practice must conform to natural laws and 

 legal enactments. A municipal engineer, there- 

 fore, should be acquainted with various branches 

 of science and engineering. There is not much 

 reference to scientific principles in this treatise ; 

 it is mainly a clear and interesting- descriptive 

 account of the methods and devices of city 

 engineering, and that entirely from an American 

 point of view. The large subjects of water supply, 

 sewerage, and street-paving are fully dealt with 

 in other text-books, and are omitted or slightly 

 discussed, but the author thinks that information 

 as to street cleansing, comfort stations, and 

 similar matters is not readily available, and that 

 city planning, street lighting, etc., require treat- 

 ing from the point of view of the taxpayer and 

 the city engineer. 



Methods of estimating and forecasting popu- 

 lation are described, and some striking statistics 

 are given of the growth of American cities. In 

 NO. 25 1 1, VOL. 100] 



a chapter on town-planning-, the chequer-board,, 

 ring, and radiating systems of streets are exam- 

 ined, and an account is given of broad roads 

 divided for automobile, truck, and street railway 

 services. As might be expected, the construction 

 of streets in the States is often less satisfactory 

 than here. For instance, in St. Paul there are 

 321 miles of plank footways, which have a life of^ 

 only three to six years. It is significant that 

 judgment suits for accidents occurring on them 

 cost the city nearly 3L per mile per annum. Con- 

 crete footways are now most generally adopted 

 with concrete kerbs. 



There is a good chapter on surveys in cities, 

 which are very systematically carried out in 

 America, and plotted records of all the surface 

 and sub-surface structures are preserved. In some 

 cities a large use is made of photographic records, 

 one purpose being to preserve records which may 

 be valuable in future lawsuits. Sprinkling mac- 

 adam or gravel roads with oil once to three times 

 a season is a practice said to have become quite 

 general, but we think is unknown here except in 

 the different form of tar spraying. The oil is 

 said to be distributed by an ordinary water- 

 sprinkling- cart. The disposal of city waste and 

 the laying out of parks and planting shade trees 

 are among-st other subjects described. 



A MANUAL ON EXPLOSIVES. 

 A Short Account of Explosives. By A. Mar- 

 shall. Pp. viii + 96. (London: J. and A. 

 Churchill, 1917.) Price 55. net. 



THE two volumes comprising the second edition 

 of Mr. Marshall's treatise on explosives 

 have been recently reviewed in these columns, 

 and the present small book consists of a con- 

 densation of parts of the larger treatise in order 

 " to present in a clear and simple manner the 

 main facts concerning explosives and their pro- 

 perties." 



After a short introductory chapter, the author 

 deals in the succeeding six chapters with the pre- 

 paration and properties of black powder and 

 similar mixtures, nitrocellulose, nitroglycerine, 

 military and commercial high explosives, and 

 smokeless powders. Another chapter is g-iven to 

 fireworks, and the remaining- three chapters to 

 the properties of explosives, ignition and detona- 

 tion, and precautions to be taken in the manu- 

 facture, handling, and storage of explosives. 



Referring to the large Congreve war-rocket of 

 24 lb. weight, which was used with g-ood effect 

 at Copenhagen, Walcheren, and Leipzig-, Mr. 

 Marshall expresses the opinion that the future 

 may see its use revived. Its great defect is stated 

 to be want of accuracy, but an obvious disadvan- 

 tage is that rockets carry their own propulsive 

 charge, so that for a given destructiveness they 

 have to be relatively very heavy. Trials have been 

 made by the Germans in the present war, but 

 rockets are unable to compete with guns, 

 howitzers, and trench mortars. 



In his concluding pages Mr. Marshall deals 



