472 



SCIENTIFIC NEAVS. 



[May 1 8, 1888. 



IXeiJielD^* 



The Starry Heavens. A Popular Intelligible Astronomy* 

 (i) By Professor W. Valentiner. Stuttgart : 

 Ferdinand Enke. 

 Every astronomer is of necessity a mathematician. As 

 such he is under strong temptation to expound his results 

 in mathematical language. This is about as judicious as 

 if an architect, on the completion of a building, should 

 insist on keeping up all the scaffolding, ladders, and other 

 appliances used in the course of the erection. We 

 must therefore congratulate Prof. Valentiner on his 

 having overcome this temptation, and on having given 

 us a survey and oversight of the starry heavens per- 

 fectly intelligible to the non-specialist. 



He considers in succession the nature of the 

 heavenly bodies — the sun, the moon, the interior planets, 

 the planetoids, the exterior planets — and devotes a special 

 section to the hypothetical planets within the orbit of 

 Mercury. A review of comets and shooting stars, and 

 of the so-called fixed stars, completes the work, which is 

 throughout drawn up with remarkable clearness, and 

 ought to prove acceptable to the educated readers who 

 have neither the time nor the training to become astro- 

 nomical specialists. 



We naturally seek to learn the author's opinions on 

 certain controverted, or, at least, undecided, points in con- 

 nection with the heavenly bodies. On the question of 

 the possible existence of a planet beyond Neptune, we 

 find no expression of opinion. The existence of an 

 intramercuria! planet, however, is thoroughly discussed, 

 with the result that we have no positive evidence of the 

 existence of such a body. An anomaly in the move- 

 ments of Mercury, not as yet explained, is admitted. 

 But this phenomenon, if, indeed, it be due to the attrac- 

 tion of unknown masses revolving in close proximity to 

 the sun, may be occasioned, not by a single planet, but 

 by a ring-like swarm of bodies, each too small to be 

 detected by us under such unfavourable circumstances. 



The supposed discovery of a satellite of Venus is 

 attributed to an optical deception. Attention, is, how- 

 ever, called to the fact that there sometimes occurs on 

 that part of the disc of this planet not illuminated at the 

 time by the sun a development of light concerning which 

 we are still ignorant. 



Concerning the origin of the small planetoids or 

 asteroids, circulating between the orbits of Mars and of 

 Jupiter, and now found to be 277 in number, little is 

 said. The supposition is mentioned — at one time enter- 

 tained — that they may be fragments of a larger planet 

 burst into fragments of some internal force. Another 

 supposition, much cherished by alarmists, was that 

 some unfortunate planet had been destroyed by the 

 shock of a comet. Whenever, therefore, a large comet 

 was seen approaching, the unscientific public were duly 

 warned that a similar fate might overtake our earth, and 

 a scare was the result. 



Concerning the supposed influence of comets upon the 

 weather, we find mention of Littrow's elaborate calcula- 

 tion that during more than 150 years the appearance of 

 comets was attended fifteen times with unusual heat, 

 but fourteen times with extraordinary cold. In ten hot 

 years 30 comets were observed, in ten years of mean 

 temperature 2t, and in ten cold years 24, so that no in- 



* Dcr Geiiirnte Himmel. Eine gemeinverstandliche Astrmiomie. 



fluence upon the character of a season can be traced. As 

 to the superstition which regarded comets as harbingers 

 of wars, revolutions, famines, and epidemics, it is in- 

 teresting to read the opinion of Seneca, here quoted. 

 This old sage, though no astronomical specialist, scouted 

 the notion that a comet was a fire recently kindled. 

 From recent investigations it would appear that of the 

 300 comets whose orbits have been calculated, 70 only 

 are elliptical and 220 parabohcal. Hence the majority 

 of these bodies cannot be regarded as permanently 

 belonging to the solar system, but rather as incidental 

 visitors. 



Concerning the probable mass of the larger comets, 

 we find here no statement ; but these bodies, of what- 

 ever apparent size, are regarded as closely related to the 

 shooting-stars, meteors, or fire-balls, especially as on 

 some occasions many of the last bodies have been seen 

 to draw after them, or to leave behind them, a train of 

 light, reminding us of the tail of a comet. 



As regards the so-called " new " fixed stars, the 

 author considers not ten new stars have been discovered 

 with certainty during the past 2,000 years. 



Among variable stars, a prominent place belongs to 

 the " star of Tryche," first noticed in 1572 in the con- 

 stellation of Cassiopoia, and which for a short time was 

 visible even in the day. Its colour was at first white, 

 becoming, as it faded away, yellow, and finally red. 



A no less remarkable phenomenon was the appear- 

 ance of a definite star in the nebula of Andromeda in 

 1876. 



We regret that space does not permit us to follow 

 the author in his account of the double stars, of the 

 nebulas, and their resolution. 



Casting a general glance at the whole work, we must 

 recognise Prof. Valentiner as an eminently judicious and 

 sober-minded astronomer, who contents himself with 

 advancing demonstrable truths, without seeking to 

 amuse his readers with vague conjectures. Hence he 

 will be found a safe and trustworthy guide — a quality 

 that is highly desirable in an age given to rash specula- 

 tion. 



Transactions of the Institution of Engineers and Ship- 

 builders in Scotland. Thirty-first Session, 1887- 

 1888. 



Among the papers here inserted we notice the fol- 

 lowing : — 



" On Liquid Fuel," by Mr. James M. Storrar. 

 The author contends that the value of hydrocarbon oils 

 is not, as generally considered twice, but about four times 

 that of coal. Gas of 70-candle power can be produced 

 from the intermediate oils. 



The " Application of Electricity to Portable Engineer- 

 ing Tools," by Mr. F. J. Rowan, C.E., is too purely 

 technical a subject for discussion in our columns. 



" Collisions at Sea ; How to Avoid, and how to Mini- 

 mise their Disastrous Results," by Mr. Lawrence Hill, is 

 a most important paper. The author mentions that for 

 the last quarter of a century the Board of Trade has 

 taken a retrograde step by consenting to certify sea- 

 going vesssls not divided into water-tight compartments 

 by bulkheads. He shows, in our opinion very conclu- 

 sively, that the additional cost of these appliances is more 

 than recouped by saving in insurance and by other 

 economies. Mr. Hill specifies a number of causes which 

 either lead to collisions or aggravate their results. 



