76 Reviews — Greenwell ^ Ehden — Roads. 



as one of the constituents in the compound known as Tile Ore : but 

 occasionally, as at Glen Farg, it shows traces of crystalline exterior ; 

 or as at Boyleston, where Mr. Craig-Christie has got it in the 

 capillary or velvet-like form. Some of the silicate of copper from 

 Lauchentyre appears to me to be coloured red by Cuprite, which 

 may also occur there in the free state. 



(230) Tenorite has not yet been proved to occur as a separate 

 Scottish mineral ; but the black Chrysocolla from Lauchentyre and 

 other mines in the neighbourhood may possibly owe its coloration 

 to this mineral. 



(288) Malachite calls for no special remark here beyond the 

 statement that it does not appear to show crystalline termination 

 at any locality in Scotland except at Sandlodge, in Shetland, where 

 it seems to have been taken for Brochantite. 



(289) Azurite is singularly rare in Scotland, and has not yet 

 been found with visible crystalline faces. (290) Aurichalcite, 

 (741) Linarite, and (739) Caledonite, well known as secondary 

 products of the decomposition of veins containing Copper, do not 

 call for any special remark in this abstract. 



DB S "V I IE "W" S. 



I. EOADS : THEIR CONSTRUCTION AND MAINTENANCE ; WITH 



Special Eeference to Eoad Materials. By Allan Greenwell, 

 Assoc. M. Inst. C. E., F.G.S., and J. V. Elsden, B.Sc, F.G.S. 

 Svo ; pp. 280. (London : The Builder Student's Series. 

 Price 5s.) 



GEOLOGISTS may well claim to have an interest in road-metal. 

 The heaps of stone by the roadside arrested the attention 

 of the ' naturalists ' in old days, and ofttimes attracted them to 

 the quarries. Thus the Kellaways Eock of Wiltshire came into 

 notice and attained a distinction which nowadays would not have 

 been accorded to it. Then each parish, whenever possible, provided 

 material for its roads, and in different parts of the country there 

 were numberless pits and quarries, many of which have long since 

 been closed and hidden beneath soil and vegetation. Even now 

 many by-roads are mended with local stone of no great durability, 

 and in parts of Somerset these ways are repaired with the basement 

 limestones and fossils of the Upper Lias. Along the principal roads 

 the freestones and rag-beds of the Oolites, however, are less frequently 

 used ; the Carboniferous Limestone, the Hartshill stone, and the 

 dark basalts of Clee Hill and Eowley Eegis have usurped their 

 place. Far better roads have resulted, although carriers have 

 complained that they cannot see their way at night so readily as of 

 yore on the present dark metal. To the introduction of railways we 

 may trace the dispersal of the better kinds of road material, while, 

 as the authors remark in the work before us, the powers acquired 

 by County and District Councils " have completely revolutionised 

 the system of road management in this country." 



