April 20, 1876] 



NA TURE 



497 



system, and tentacles — underwent a marked decrease ; so that at 



last I was only able to obtain specimens one half or one quarter 



the ordinary size of Aurelia aurita, and having nearly all their 



natural rose-pink colour discharged. I believe that these two 



•^'cnomena — the loss of colour and the diminution in size — are 



ued to one another in a very intimate manner. Just at the 



:;e of year when these two phenomena began to manifest them- 



ves, I observed that all the specimens of Aurelia I met with 



: e infested by a species of crustacean, which lodged chiefly in 



the ovaries and nutritive canals. These crustaceans appeared to 



devour with avidity all the coloured parts of their hosts, and I 



think it was probably due to the ever-increasing numbers of these 



parasites that the size of the individuals composing the incoming 



renerations of Aurelia continued to become more and more 



linutive. I shall, however, attend to all these points more 



^ely next year, after which I shall doubtless be able to speak 



V. ith more certainty regarding them. 



SCIENTIFIC SERIALS 



American yournal of Science and Arts, Afarch. — In this 

 number Mr. Tiouvelot directs attention to the phenomenon of 

 what he calls "veiled solar spots." During last year, the chromo- 

 sphere has been notably thinner than usual, and the granulations 

 smaller and less numerous, rendering more conspicuous the 

 light-grey coloured back-ground between the granules. The 

 veiled spots are seen through the chromosphere that is spread 

 over them like a veil ; they are, like ordinary spots, true openings 

 of the photosphere ; they are scattered throughout all latitudes, 

 though more complicated in regions where the ordinary spots 

 make their appearance. Mr. Trouvelot has observed spots at 

 least w ithin 10 degrees of the north pole of the sun (very few of 

 the ordinary spots have hitherto been observed beyond 40). — 

 Prof. Kimball describes an ingenious arrangement by which he 

 lonstrates that the law affirming the coefficient of friction on 

 inclined plane to be constant for all velocities, is not strictly 

 li lie. The sliding box had a cover 6 feet long, wiih strips lT 

 smoked glass upon it, on which a tuning fork, fixed above to an 

 independent support, traced a wave-line as the box slid down, 

 thus giving a perfect autograpliic register of the experiment. — A 

 new method of measuring the velocity of electricity is described 

 by Prof. Lovering. He avails himself of Lissajous' method of 

 compounding the rectangular vibrations of two tuning forks, the 

 reflected beam entering a telescope. The forks being maintained 

 in vibration by electro-magnets and brought into unison, the 

 resultant orbit seen in the telescope is invariable. A length of 

 resistance coil is introduced sufficient to change the orbit to some 

 other in the series, and this change reveals the amount of retard- 

 ation of the one fork's vibrations, due to the inserted resistance. 

 — Prof. Mallet discusses the constitutional formula; of urea, uric 

 acid, and thefr derivatives. — A new trilobite, Dalmanitis dtntata 

 is described by Dr. Barrett, and Prof. Marsh gives (in an 

 appendix) the principal characters of Tillodontia, a 'new order 

 of extinct mammals found in the Eocene deposits of North 

 America. — Mr. Wallace gives an account of some flint implements 

 found in the stratified drift in the vicinity of Richmond, Virginia, 

 and there are one or two notes on points in American geology. 



Pogoendorff" s Atmalen der Physik und Chetnie, No. 12, 1875. 

 — A few years ago, separate researches were published by Narr 

 and Stefan, on the conduction of heat in gases. M. Winkel- 

 maim here extends the inquiry, his object having been to ascertain 

 how far production of currents and radiation affected the velocity 

 of cooling, to study the behaviour of more gases, in order to a 

 fuller comparison with theory, and to determine the dependence 

 of heat-conduction of gases on temperature (the last is reserved 

 for another paper). His apparatus was substantially hke Stefan's, 

 and he examined ten gases. The numbers obtained differ con- 

 siderably from those of Narr, in whose experiments, he thinks, 

 currents had not been avoided, and had contributed not a little 

 to the velocity of cooling. Stefan's value for air is 6 per cent, 

 greater than the author's, and this difference is explained by 

 radiation, which Stefan had not taken into account. — M. Weber 

 studies the coloured products obtained through the action of sul- 

 phur and selenium on sulphuric acid anhydride. He has got from 

 this action a new oxygen compound of sulphur and a correspond- 

 ing substitution product of selenium. The former contains twice 

 as much sulphur as sulphuric acid (57 "14 per cent.), and the 

 formula assigned is Sj O3. M. Weber proposes for it the 

 name of sesquioxide »f sulphur, or dithionoxide. In the dry state 

 it forms bluish-green crystals, and is like malachite in structure. 



Liquid only in the moment of production, it soon solidifies and 

 cannot b€ fused again without decomposition. In a cool 

 chamber, decomposition occurs but slowly. The selenium com- 

 pound is denoted by the formula Se SO, (it requires 49'68 per 

 cent, selenium, 20"i2'per cent, sulphur.) The crystallised sohd is 

 of a dirty green colour, and it is much more stable than dithion- 

 oxide. — Before hi, death. Prof. J. J. Miiller was engaged in 

 experimenting on the influence of insulators on induction ; and 

 he communicated to Dr. Fiedler the following results, (i) 

 Insulating media exercise, on the strength of induction, the 

 opposite mfluence to the induced magnetism of the conductors. 

 (2) Static electricity accumulated on insulators, exerts an influence 

 on the strength of induction. Dr. Kleiner here gives details of 

 the experiments, from which these conclusions were formed. — In 

 a paper on thermo-electricity, M. Kohlrausch considers that for a 

 theory of the phenomena, we do not need an immediate action 

 of the contact surfaces, but can arrive at full agreement with the 

 facts by assuming electromotive forces in the interior of the con- 

 ductors, the places of contact having only a secondary influence. 

 In every thermopile, when in action, there necessarily is, with 

 the difference of temperature, a streaming over of heat from the 

 hotter to the colder junction. The difference of temperature of 

 the soldered parts has hitherto been thought the cause of the 

 electromotive force ; but with equal right we may take as basis 

 the other inseparable circumstance, and suppose that with a heat 

 current in a determinate mass, dependent on the nature of the 

 conductor, an electric current is connected (provided that other 

 electromotive forces are fir^t excluded). These ideas are deve- 

 loped in the paper. — M. Holtz communicates the results of various 

 attempts to improve the simple " influence " machines ; and Pro(. 

 Lommel fumisnes an elementary treatment of some optical pro- 

 blems, the smallest deflection in the prism, the achromatic prism, 

 and the elementary theory of the rainbow. — M. Edlund deals 

 with two objections to his unitarian theory of electriciiy ; one by 

 Prof. Newman, that to explain unipolar induction, the presence 

 of at least two electric fluids is necessary ; the other by M. 

 Baumgartner, that tlie unitarian theory seems to contradict the 

 supposition that vacant space has no conductivity for the galvanic 

 current. — M. Sadebeck contributes some mineralogical studies 

 from Kiel University ; and among other subjects treated in this 

 number are, the behaviour of electricity in electrolytes (Budde) and 

 the alteration of the velocity of light in quartz through pressure 

 (Mach and Merten). 



Memorie Delia Societa degli Spettroscopisti Italiani, Sept. 1875. 

 — Prof. Tacchini continues his detailed remarks on sun-spois 

 and faculae observed by him at Palermo in 1873. The spectral 

 lines of the prominences in the neighbourhood of faculas are also 

 fully given, the lines which appear to have been seen in nearly 

 every eruption are D, b^ b- b^ b^, 4,943, 5,031, and 5,316; the 

 other lines less frequently seen are 5,263, 5,272, 5,282, 5,226, 

 5,232, 5,234, and 5,195. 



Oct. 1875. — Prof. Tacchini gives a note on his observations in 

 the previous number, and remarks the greater number of erup- 

 tions of magnesium on the western limb than on the eastern ; 

 the numbers on the former being more than double those on the 

 eastern. The actual numbers for each month in 1873 are given. 

 The number of eruptions in the northern and touthern hemi- 

 spheres are equal to each other. The zones of maximum erup- 

 tions appear to be between N. lat. 10" and 20*, and S. lat o* 

 and 10°. — Communications from Father Secchi, Prof. Doma, 

 and Prof. Tacchini on the partial solar eclipse of Sept. 29, 1875. 

 It is remarkable that the first contact was observed by the spec- 

 troscopic method some seconds later than by the simple tele- 

 scopes, and the last contact several seconds earlier. — Drawings 

 of llie solar prominences during the months of May and June 

 1874 by Secchi and Tacchini accompany this number. 



Zeitschrift der Oesttrreichischen Gesellschaft fiir Metcorologie, 

 Dec. I, 1875. — The concluding part of Htrr Wild's paper on 

 the late congresses appears in this number. Against what has 

 been said of these gatherings, that their sole result would be 

 the accumulation of millions of useless observations upon the 

 millions that have already been pubhshed, he contends that in 

 his opinion observations are useless only when they are faulty 

 and inaccessible ; and that he has found himself hampered, not 

 by their great quantity, but by their deficiencies, inconvenience 

 of form, or variety of arrangement. It is true that out of mil- 

 lions of figures perhaps only some thousands prove of value to 

 the invesUgator ; but who can decide which will and which will 

 not eventually be used ? Registers intended for publication are 

 submitted to a more careful revision than those preserved only 



