292 



NATURE 



{July 25, 1889 



matter, and drawing^ it towards other particles, is capable 

 of conversion into a repelling force. 



A body, half of whose mass has had its attracting 

 tendency converted into a repelling tendency, will have a 

 specific gravity of zero, and if placed in a vacuum will 

 neither rise nor fall. 



If more than half the mass of a body has had its 

 attracting tendency converted into a repelling tendency, 

 it will rise into the air, and, passing the limits of the 

 atmosphere, will continue moving away from the earth 

 with a velocity for a time accelerated by terrestrial 

 repulsion, but tending more and more towards uniformity 

 as it proceeds. 



The " flying machine " was constructed of a substance 

 that had undergone such a conversion. By means of a 

 regulator the resultant of the attracting and repelling 

 tendencies could be turned in any direction, and so the 

 velocity of the machine could be increased or diminished 

 ad libitum. 



It was in this machine that Mr. Stranger made his 

 journey to the planet Mars, and the work mainly deals 

 with Martian history, the customs of the inhabitants, and 

 adventures and incidents en route. The two satellites of 

 Mars were met, and their diameters, distance from their 

 primary, and period of revolution are supposed to have 

 been approximately measured by the adventurer. Having 

 reached the planet in safety, a long description is given 

 of the startling difference one would observe on attempt- 

 ing to walk upon a globe where the surface gravity was 

 only three-eighths that of the earth. 



The Marsians, Martians, or Marticoli, as Prof Young 

 would call the inhabitants of our ruddy brother, were, 

 according to the author, living very happily under a form 

 of Socialism ; and food was almost as free and plentiful 

 among them as the air which they breathed, because 

 they had learnt to manufacture it from its chemical 

 elements — oxygen, hydrogen, carbon, and nitrogen — which 

 existed in abundance on their planet as on the earth. In 

 this Utopia, not only were electric lights in every house 

 and street, and the phonograph an instrument in common 

 use, but the sound-figures drawn upon the revolving 

 cylinder were used as the representation of speech, such 

 characters being truly phonetic. It appears strange, 

 however, that although the Martians had attained such a 

 high degree of civilization, yet they had no knowledge of 

 gunpowder or any explosive whatever, or of any kind of 

 telescope, a circumstance which seems contrary to our 

 ideas on the evolution of inventions. 



The inhabitants of Mars were supposed to have come 

 from the earth, and their transference was effected in the 

 following manner. A sun, accompanied by satellites, in 

 revolving at an immense distance round a larger sun 

 passed very near to Mars and the earth, and caused them 

 to approach one another. In the words of the writer, 

 " The common centre of gravity of the four bodies 

 must have been so situated as to have almost neutralized 

 the resultant of the attraction of the earth and Mars 

 towards their respective centres, so that on one part of 

 the earth's surface the attraction of Mars would overcome 

 that of the earth, and gently and slowly draw a body from 

 its surface to its own ; while in other parts the attraction 

 of the earth would be more powerful and prevent this. 

 The two planets must also have been so near that their 



atmospheres were mingled, and hence the transference 

 did not result in the death of those who had thus to 

 emigrate against their will." 



Such an explanation as this, of some perplexing pheno- 

 mena, shows an intimate knowledge of the laws of gravi- 

 tation. Again, whilst on a visit to one of the small 

 Martian satellites, a fragment of rock was broken off, and 

 instead of at once falling down on the ground, as it would 

 have done on the earth or Mars, it sailed slowly and grace- 

 fully away, until it came in contact with another rock 

 several yards off, when it descended softly and gently to 

 the ground with the motion of a falling flake of snow in a 

 perfect calm^an imaginary incident in perfect accord- 

 ance with the laws of gravitation. Many similar incidents 

 are just as ably treated, and the description of a meteor 

 is worth repeating here : — " Its general shape was globular, 

 and before we had got close to it, it seemed a perfect 

 sphere, but at this near distance it looked like a round 

 mass of incandescent liquid covered all over with bubbling 

 and boiling protuberances, which every now and then 

 emitted huge jets of flaming gas, or, detaching themselves 

 from the general mass, shot forth as globules of white 

 shining liquid. We were, in fact, the spectators of the 

 early formation of a little world, a sun in miniature, but 

 resembling the sun rather as it was many ages ago than 

 as it is now." 



We might quote many other descriptions of phenomena 

 all agreeing with acknowledged facts and rigid scientific 

 principles. We refer to observations of the extreme 

 blackness of the shadows cast by the rocks of the 

 Martian satellite which was supposed to have been 

 visited, the noiseless explosions of the meteor above de- 

 scribed, the apparent motionlessness in space of the flying 

 machine, in spite of its enormous velocity, the inferior 

 attraction of Mars and its satellites, and the explanation 

 of how men got transferred from the earth to Mars. 

 Indeed, the work is as interesting to us as to the general 

 reader, and as a means of disseminating scientific 

 knowledge may be eminently useful. 



R. A. Gregory. 



OUR BOOK SHELF. 



The Uses of Plants : a Manual of Economic Botany, with 

 special refere7ice to Vegetable Products introduced during 

 the last Fifty Years. ' By G. S. Boulger, F.L.S., F.G.S. 

 (London : Roper and Drowley, 1889.) 



That a good manual of economic botany is really wanted 

 no one who knows anything of the subject will deny, and 

 pending the appearance of a satisfactory book any contri- 

 butions towards such an end must be accepted with thanks, 

 always supposing that those contributions are trust- 

 worthy and intelligible. Articles by competent writers 

 on the various products of the vegetable kingdom are 

 to be found in encyclopaedias, and occasionally special 

 subjects are taken up and worked out by individual 

 writers ; but the great want is a thoroughly good book 

 treating of the whole range of economic plants. 



The Httle book before us, which comprises 224 pages, 

 is not one that will help to such a desirable end. 



The plan adopted by the author, of classifying the 

 products under distinct heads, is undoubtedly the best ; 

 but it is not equally carried out in all parts of the work. 

 Although, under " Food, Food Stuffs, and Food Ad- 

 juncts," we find the products divided under different sec- 

 tions, as starches, sugars, roots, fruits, &c., no attempt has 



