Duncan Bryant is a retired space plasma physicist who spent mostof his career at the Rutherford-Appleton Laboratory in Oxfordshire, England. For manyyears he has been challenging a widely accepted theory, that auroral electronsare accelerated by double layers, on the grounds that it contains a fundamentalerror (allegedly, an implicit assumption that charged particles can gain energyfrom conservative fields). It is, of course, right that models of particleacceleration in natural plasmas should be scrutinized carefully in terms oftheir consistency with basic physical principles, and I believe that Dr Bryant hasperformed a valuable service by highlighting this issue. He maintains thatauroral electron acceleration by double layers is fundamentally untenable, andthat acceleration takes place instead via resonant interactions with lowerhybrid waves. In successive chapters, he asserts that essentially the same process canaccount for electron acceleration observed at the Earth's bow shock, in theneighbourhood of an `artificial comet' produced as part of the ActiveMagnetospheric Particle Explorers (AMPTE) space mission in 1984/85, in thesolar wind, at the Earth's magnetopause, and in the Earth's magneto-sphere. Theevidence for this is not always convincing: waves with frequencies of the order of thelower hybrid resonance are often observed in these plasma environments, but ingeneral it is difficult to identify clearly which wave mode is being observed(whistlers, for example, have frequencies in approximately the same range aslower hybrid waves). Moreover, it is not at all clear that the waves which areobserved, even if they were of the appropriate type, would have sufficientintensity to accelerate electrons to the extent observed. The author makes apersuasive case, however, that acceleration in the aurora, and in other plasmaenvironments accessible to in situ measurements, involves some formof wave turbulence.In Chapter 2 it is pointed out that the Debye number (the number ofparticles in a sphere of radius equal to the Debye length) is actually rather higher in thesolar wind and the Earth's magnetosphere than it is in any laboratoryplasma: in this sense space plasmas are more `ideal' than laboratory ones. Changes inmagnetic field topology occur in both the magnetosphere and tokamaks, butin the former case the term `magnetic reconnection' tends to be used only in asteady state context: temporary or sporadic changes in field topology at themagneto-sphere/magnetosheath boundary, for example, are described instead as`flux transfer events'. Reconnection in tokamaks, on the other hand, isgenerally regarded as an intrinsically time dependent process. Such subtledistinctions in terminology should be borne in mind by any fusion researchersreading this book.Dr Bryant's writing style is informal and often entertaining. A good example ofthis, from Chapter 3, is the following: ``Auroral arcs can be bright enough touse as a reading lamp, although it would be something of a waste to use it assuch, since the aurora is vastly more interesting than any document (even thisone).'' Chapter 3, indeed, is the best part of the book, covering as itdoes theauthor's principal area of expertise, namely the aurora. The author gives averyclear account of auroral phenomenology, in particular observations of auroralelectrons, before considering the merits of rival acceleration mechanisms.The approach is largely non-mathematical, with few equations: those that doappear are not numbered (it would have been better if they had been). It has tobe said that the author is not always rigorous or consistent. For example,acceleration a is first defined `in its most general sense' to be rate ofchange of speed, rather than velocity: thus, according to this definition,a = 0 in a static magnetic field. A few pages later, the same symbol is used todenote the modulus of the rate of change of velocity: this, of course, is finite in astatic magnetic field. Such elementary distinctions matter, because in order toaddress the issue of whether or not electrons are `accelerated' in static orquasi-static fields, one must first define unambiguously what `acceleration'means. It is stated in Chapter 2 that the Larmor radius of a particle isproportional to its magnetic rigidity divided by the magnetic field componentnormal to the particle trajectory. This, of course, is incorrect: it is theparticle's momentum component normal to the field which defines the Larmorradius. The book contains a number of statements which are eithermisleading or demonstrably incorrect. For example, at the end ofChapter 3, and again at the end of Chapter 4, neutral beam injection (NBI)in tokamaks is invoked as a precedent for lower hybrid wave excitation by cross-fielddrifts. Although it is true that lower hybrid waves can couple to energeticions in a tokamak, and could in principle be amplified by fusion alpha particles[see N.J. Fisch, J.-M. Rax, Phys. Rev. Lett. 69 (1992) 612], NBI has not, to the best of my knowledge, been used as a source of such waves.In Chapter 9, referring to solar flares, the author states that ``characteristic products of the accelerated electrons areX rays generated by synchrotron radiation in the remaining magneticfields''. In fact, flare accelerated electrons produce X rays via bremsstrahlung, themagnetic field and particle energies being such that synchrotron radiationoccurs at microwave frequencies instead (the more general term `gyrosynchrotronradiation' tends to be used by solar flare researchers, in recognition of thefact that the electrons producing the bulk of the emission are only mildlyrelativistic). Indeed, bremsstrahlung X rays and gyrosynchrotron microwavesprovide important sources of information on the distribution function offlare accelerated electrons, but the author makes only a brief mention of suchobservations, preferring to concentrate on direct measurements offlare accelerated electrons at the Earth's orbit, despite acknowledging thatuncertainties in propagation effects make it very difficult to reconstructconditions at the Sun from such measurements.Similar remarks apply to the final chapter, on acceleration of cosmic rayelectrons. Again, attention is focused almost exclusively on measurements ofparticles rather than the radiation signature of those particles, in this casesynchrotron radiation by ultrarelativistic electrons. No mention is made ofradio and X ray data, indicating that electrons with energies of up to around1014eV are being accelerated at shocks associated with shell typesupernova remnants. Interestingly, resonant acceleration of electrons by lowerhybrid waves has been invoked by A.A. Galeev [Sov. Phys.-JETP 59 (1984) 965] as a mechanism for the production of cosmic ray electrons: althoughGaleev's paper is not cited in this book, the process he describes is verysimilar to that proposed by Dr Bryant for electron acceleration in theaurora and other near Earth plasma environments.The book contains a number of physics errors. For example, on page 17 the timederivative of a magnetic field is equated to an induced electric field, ratherthan the curl of one. On page 21, the author invokes Larmor's formula for thepower radiated by a non-relativistic charged particle, and then combinesit with the relativistic relation between acceleration and energy to estimate themaximum acceleration rate. The book has also been badly proofread. For example,Figure 1.15 appears twice: where it is first used, on page 8, it is clear that theaccompanying caption and text refer to a different figure. I found severalerrors in the reference list (one of my own publications is cited as two separatepapers, with both citations containing inaccuracies). Having said that, thereference list is impressively comprehensive and eclectic. It includes, forexample, Swift's `Gulliver's Travels': a spacecraft in the magnetosphere iscompared to Gulliver in Brobdingnag, the magnetosphere being, in somerespects, a vastly scaled-up version of a laboratory plasma. The author measures particlemomentum in units of 10-21 Ns ≡ 1 zNs - not, I suspect,a unit used often by nuclear fusion researchers. There are many typographicalerrors (in addition to the physics errors noted above).At the end of the book listings are provided of three programs, written inQBasic (a PC compatible version of BASIC), which illustrate simple models of particledistribution evolution under various conditions, and in particular theformation of a bump-on-tail distribution when particles undergo random energy exchangeswith waves. These are instructive and illuminating, although it would have beenmore useful if diskettes had been provided with the book rather than hard copylistings. Questions and exercises are also included, again with the purpose ofillustrating the author's heterodox ideas regarding particle acceleration. Heasks, for example, what the accelerator of Newton's apple was: according to DrBryant, the obvious answer (`the Earth') is incorrect, since it was radiationfrom the Sun which raised the apple's material against the force of gravity inthe first place. The answer to the question depends, of course, on what onemeans by `acceleration': as I have discussed, the author is not whollyconsistent inhis definition of this term.This book will, inevitably, be of more interest to space plasma physicists thanto fusion researchers, although proponents of lower hybrid current drive intokamaks may be gratified to see evidence of a similar process playing animportant role in such a wide range of natural plasma environments. Despitesomeerrors, omissions and inconsistencies, there is no doubt that the bookprovides auseful record of Dr Bryant's valuable contributions to the study of electronacceleration in the aurora and elsewhere.