652 Christmas Books Nature Vol. 276 7 December 1978

latest velsion of the world picture book ments, crystals, gemstones, economic Armchair geology that grandma bought us for our eleventh minerals and the building of a mineral birthdays. There is little one can fault collection. This book too is but a variant THE mere statistics of wilderness areas Banyard on, lest it be lack of inspiration; of its numerous predecessors over the are impressive enough. The Earth's but it is at times like this that one comes years; but within its stated limitations surface contains something like 18 x 10'; to appreciate Anthony Smith's sense of it is far more authoritative and better km 2 of desert, about half of which is personal quest and involvement. produced than most. accounted for by Australia and the Involvement of another kind is inherent Aggregates of minerals (tllat is, rocks) Sahara. And to this 12 % of the total in Alan Woolley's JIIustrated Ellcyclo­ are generally less colourful than some land surface must be added II % under paedia of the Mil/era! Killgdolll, (Hamlyn: of the pure minerals and thus less popular permanent ice cover, 9 % covered with Feltham, UK, £5 .95) for mineralogy as collectors' items. The most colourful mountain, a further 9 ~ ( ; of cold and in its simplest form, the collection of specimens in Rucks (J( the World, (Per­ waterlogged tundra, and 29 ~/~ of other­ minerals, is the most popular of geology's gamon : Oxford, £ 15), which is not a wise uncultivable continent comprising branches, at least as far as the amateur book but a neatly-mounted set of 36 of semi-arid regions, bare rock, frost-prone is concerned. I presume that this new the world's most basic rocks, are the areas, and so on. Taking the oceans into Hamlyn encyclopaedia has been produced laterite, the serpentinite and the ignim­ account now, only 9/:, of the Earth's largely with the non-geologist in mind, brite; but despite the preponderance of surface can be cultivated and only about but non-mineralogical Earth scientists greys the collection is a fascinating one, a third of that is actually tilled. will also find it useful as far as it goes. not least by the way it suddenly appears To be able (by courtesy of the BBe) Its main defect as far as working geologists in one's hand without all the effort of to escape from man's narrow well-beaten are concerned is that it only goes as far collecting individual samples. Armchair tracks from time to time to make a series as about 300 of the world's 2500 or so geologists of the world wi II rejoice; but of television programmes about the minerals (generally the most common schoolteachers wi II not be displeased world's varied wildernesses, Anthony and widely distributed but including a either, for a good collection of basic rocks Smith, the naturalist-broadcaster (as few rarer ones of greater than usual is , of course, essential for beginning opposed to the political scientist-broad­ interest to mineral collectors). geology classes. The samples are rather caster and the medical journalist of the For the chosen 300, however, all the small (up to about 4 cm across) and, being same name), was indeed privileged. His essential information is given (composi­ mounted, cannot easily be handled by a book, Wilderne.)".\" (Allen and Unwin: tion, hardness, lustre, occurrence, and group of students. As a purely visual Hemel Hempstead, UK. £7.50), though so on) and the colour photographs are display, however, the set can hardly be obviously a spin-off from the series, is good. On the other hand, the book is far faulted. Peter J. Smith not the "book of the film" in the usual from being a mere list, for there are ------sense but, rather, an independent personal summary chapters on the Earth's structure Peter J. Smith is Reader in the Depart­ account involving a mixture of descrip­ and history, crustal composition, minerals men( of Earth Sciences at fhe Open tion, observation, reaction, interpreta­ and rocks in their geological environ- University. Milton Keynes. UK. tion, background and anecdote relating to his visits to the world's largest ice-sheet (Antarctica), the biggest tropical forest (Brazi!), a large desert (central Australia), the highest mountain range (Himalayas), sional) of what has been achieved in this the tundra (northern Canada) and the For budding fit::ld. It is possible to make holographic most extensive swamp (Sudd). holograpbers pendants, three dimensional abstract light "Discovering a nest", says Smith patterns and rainbow cylinder holograms; at one stage with unconscious irony , "is Understanding Holography. By Michael and even Salvador Dali has shown an more rewarding than being shown ten Wenyon. Pp. 176. (David and Charles: interest in the technique. As for the future of them." Precisely-which is why all Newton Abbot and London, 1978.) £5.50. of holography, the author tells us that travel books are inherently unsatisfactory. holographic movies already exist and Whether you like or dislike this one will could well become a viable proposition depend on whether or not you can bear to THIS book is intended for the general on a large scale. There is, however, a visit places through anOlher person's reader and starts wilh two cha pters about sinister comment that " life-like 3D movies words. Generally I cannot; but because light and the laser in which various ideas could also be used in the future for of the unusual nature of the places, I relating to waves, coherence, interference, psychological conditioning or brain­ managed to overcome the resistance in stereoscopic images, stimulated and washing". Holographic television. it this case and was rewarded with a pleasant spontaneous emission, and so on, are seems, is unlikely to be realised in the near afternoon, not least because of the superb introduced in a non-matilematicalmanner. future. Apart from its obvious entertain­ colour plates. There follows a short digression on the ment value, holography can be used in a But if Smith's book is the closest most applications of lasers in such fields as more serious vein, as illustrated by the of liS are likely to get to the true wilder­ medicine and laser light shows before a accounts of applications in the study of ness, the phenomena described by P. J. discussion of the principles of holography. the vibration modes of musical instru­ Banyard in his Natural Wonders of the The basic ideas of holography are con­ ments and the testing of car tyres. World (Orbis: London. £5 .95) are more sidered from the diffraction grating ap­ The final chapter is an account of how accessible. as they lie mainly within proach, and a well informed reader may to make your own holograms with simple man's proportionally small terrestrial have thought that more insight into the equipment. Perhaps the easiest way of domain. Landforms, ice patterns, water process would have been obtained, had making a simple hologram is to use con­ displays, atmospheric phenomena, gurg­ the idea of the grating been extended to ventional fine grain film and to ensure lings from the Earth's interior, exo tic include the Fresnel zone plate. The effects there is a small angle between the object flower arrangements-they are all here of the size and spectral content of the light and the reference beam. ft is a pity there in a combination of pleasing pictures source used in the reconstruction process is no mention of this experiment, if for no and straightforwardly factual text. It are, surprisingly, not considered in detail. other reason than the relative cheapness makes for a nice browse; but there The chapter on display holography of the photographic material. Also the is a sense of deja vu about it alI, for makes entertaining reading and there are double exposure scatter plate experiments what we are looking at is just the many illustrations (necessarily two dimen- could have been described as they are easy CI Macmillan lournals Ltd 1978