August 8, 1889] 



NATURE 



;4i 



points, and by a judicious overhauling might be made 

 into a good book, for it is precisely one of those works 

 that would have been better if the author had taken 

 more pains. 



THE MIDDLE LIAS OF NORTHAMPTONSHIRE. 



The Middle Lias, of Northamptonshire. By Beeby 

 Thompson, F.G.S., F.C.S. Pp. 150. (London: 

 Simpkin, Marshall, and Co., 1889.) 



THE sub-title of this work explains that the subject 

 is considered stratigraphically, palccontologically, 

 economically, as a source of water supply, and as a 

 mitigator of floods. 



The author commences with some account of the 

 beds grouped as Middle Lias, there being considerable 

 difference in the classifications adopted by geologists, 

 from the fact that the distinction between Middle and 

 Lower Lias is mainly dependent on fossils. In con- 

 sidering this matter we have to deal with a series of clays, 

 exhibiting a succession of organic remains, intimately 

 connected, and yet characterized at different horizons 

 by certain species of Ammonites. There are no strati- 

 graphical planes of demarcation for our guidance, and it 

 is merely a matter of convenience (or inconvenience as 

 the case may be) to adopt a divisional line. The subject 

 was discussed at some length in Nature (vol. xv. p. 

 1 1 3) and we may therefore pass on to say that Mr. 

 Thompson includes in his Middle Lias the zones of 

 Avwwnites margaritatus and A. spinatus, in this respect 

 following the plan adopted by the Geological Survey. 



As with the junction of the Middle and Lower Lias, 

 so with that of the Middle and Upper Lias, there is, at 

 any rate in Northamptonshire, evidence of intimate con- 

 nection. We find, in fact, a "transition bed "between 

 Middle and Upper Lias ; and this, although but a few 

 inches thick, has furnished a large number of fossils to 

 Mr. T. Beesley, Mr. E. A. Walford, and the author of 

 this work. Much interest attaches to this transition bed, 

 from the fact that it contains an admixture of Middle and 

 Upper Lias fossils, although a larger proportion of the 

 former. Among the Upper Lias Ammonites found in it 

 are A. coniiuunis, A. annulatus, and A. Holandrei j 

 and it is noteworthy that A. commuitis and A. crassus 

 are recorded also from the Marlstone below (zone of ^. 

 spinatiis). All ihese species are very closely connected, 

 and the abundance of A. comiminis in the lower beds of 

 the Upper Lias of some parts of England, serves to show 

 that its value as a zonal species in the uppermost beds is 

 veiy local. We note that Mr. Thompson speaks of 

 " falcifer " Ammonites — a mode of expression with which 

 we fully sympathize, for the species, unfortunately, are 

 becoming so much subdivided that before long no one 

 but a specialist in Ammonites will dare to identify any 

 particular form. 



The work before us well illustrates the progress made 

 in our knowledge of the details of British formations. 

 The author has evidently laboured long and earnestly at 

 his subject, and indeed no one but a resident geologist 

 could have given us such particulars of the subdivisions 

 of the Middle Lias and the fossils that occur in the 



different layers, for some sections yielding valuable in- 

 formation are open but for a short time, and the geo- 

 logist who spends but a few weeks in a district may fail 

 to find exposures of every zone. Moreover, now increasing 

 attention is given to the biological history of species, the 

 precise position they occupy in the series of strata is of 

 the greatest importance. Hence the work is of value not 

 merely from a local point of view, but as contributing 

 much material that will help towards a full knowledge of 

 the Lias of Britain. 



Summarizing his results, Mr. Thompson catalogues 94 

 genera and 273 species from the Middle Lias, includ- 

 ing, however, but few of the Foraminifera. Vertebrate 

 remains are scarce, but the conditions of deposit, as 

 remarked by the author, were to a large extent shallow 

 water and littoral marine— conditions that appear to be 

 generally unfavourable to the preservation of the fishes 

 and reptiles of the Lias. 



The economic products of the Middle Lias are duly 

 noted by the author. These are practically confined to 

 building-stone and brick earth. The valuable iron ores 

 found in some localities hardly come into the area, 

 although some beds were at one time worked at King's 

 Sutton. 



Considerable attention has been given by the author to 

 the question of water-supply, and in 1881 he suggested 

 that the supply for the town of Northampton might be 

 increased by the formation of a number of dumb-wells. 

 In this way he anticipated that the surface drainage 

 might be conducted underground through the Upper Lias, 

 so that the porous beds of the Middle Lias would be 

 utilized as a natural reservoir, while at the same time the 

 liability to floods would be lessened. The scheme was 

 brought before the Town Council, but, as the author 

 candidly admits, the Water Committee, after consulting 

 Sir Robert Rawlinson, were fully justified in rejecting it. 

 It is, however, far from apparent that the scheme was 

 faulty in theory. The natural storage of water has been 

 advocated by several authorities, and it has been put into 

 practice in India. The whole subject is worthy of close 

 attention, and we can commend this portion of Mr. 

 Thompson's book to those interested in the questions of 

 water-supply and drainage. H. B. W. 



OUR BOOK SHELF. 



A Dictionary of Explosi%>es. By Major J. P. Cundill, R. A. 



Published by the Royal Engineers Institute. (Chatham : 



Mackay and Co., 1889.) 

 It is impossible to look at this listof explosive substances 

 prepared by Major Cundill without coming to the conclu- 

 sion that the chemist has had little to do with the most of 

 them. Mixtures are things which do not delight the 

 chemical mind either in an explosive substance or any- 

 thing else. It places too much reliance on some mechanical 

 operation, mixing or something of that kind, to give the 

 chemical notion of exactness in its composition. 



A theoretically perfect explosive would be a substance 

 like hexanitro-benzene, Cfi(N02),j, but this has not yet been 

 made. The variety and curious nature of substances and 

 mixtures, many of them solemnly patented, described in 

 this book, are most interesting. One, amongst several, is a 

 mixture of carbonate of lime, chloride of sodium, and 

 urine evaporated with charcoal. It seems pretty harmless 

 as an explosive. Not so, however, many other mixtures 



