496 



NA TURE 



yMairk 20, 1884 



rior nuclear emi'-sion are supposed to oscillate in presence of the 

 sun like the needle of a compass in jiresence of a magnet. Hut 

 M. Fnye sees in these changes mthing but the effect of a rotatory 

 motion powerfully affected l>y solar attraction. Under these 

 conditions the rotation may acquire irregular pendulant vibra- 

 tions without having recourse to the intervention of polar forces. 

 — Explosive gaseoui mixtures : calculation of their temperatures 

 and specific heat at the moment of explosion (continued), by MM, 

 Bertlielot and Vieille. Tables of the results of the-e experiments 

 are appended for the oxyhydric and oxycarbonic mixtures, for 

 cyanogen, and the carburets of hydrogen. — Note on a letter of 

 tlie astronomer Mcchain in connection with the completion of 

 the triangulation of S[)aiii and the extension of the meridian to 

 the Balearic Isles, by M. ]. lefort. — On a differential equation 

 of the third order, by M. E. Goursat. — On the decomposition of 

 polynomes which admit only of primary divisors of a determined 

 form, by M. Lefebure. — On the remarkable variation of the 

 nucleus of the Pons Brooks comet (one illustration, by M. Ch. 

 Ttjiied. — On the barometric oscillations produced by the 

 Krnkatoa eruption, by M. P. Tacchini. — On the crepuscular 

 and auroral lights oliserved at Morge?, in Switzerland, during 

 tlie winter of 1883-84, by M. Ch. L'ufour. — On a method for 

 mcisuring the coefficient of cubic expansion of solid substances 

 in the form of minute particles, by M. J. Thoulet. To deter- 

 mine the coefficients of these bodies the author employs a solution 

 of iodide of mercury in iodide of p ita'sium. The extreme delicacy 

 of the process is shown by its application to quartz, which yields a 

 coefficient of o'ooco357 compared with M. Fizeau's O'cooo36i9. 

 — On the action of two consecutive parts of the same electric 

 current, by M. A. Buguet. — On the spectrum of absorption of 

 water ; preliminary studies connected with the spectral analysis 

 of the rays transmitted through a more or less dense layer of 

 water, by MM. J. L. Soret and Ed. Sarasin. — Action of electric 

 effluvia on oxygen and nitrogen in the presence of chlorine, by 

 M.\l. P. Hautefeuille and J. Chappuis.— Observations on the 

 formula of sime sal ammoniac, by M. R. Engel. — Observation 

 relative to a note of M. Calmels on the poison of Batrachians, 

 by MM. A. Gautierand Etard. — On the Malpighiaa vessels of 

 the Lepidoptera, by M. Cholodknvsky. — On an aberrant form 

 of the phylum Sporozoa, by M. J. Kunstler. — On the presence 

 of manganese in the white cipoline marbles of Carrara, Paros, 

 and the Pyrenees ; geological deductions, by M. Dieulafait. 

 Berlin 

 Physical Society, February 22. — Prof. Lnndolt produced a 

 cylinder of solid carbonic acid he had prepared about an hour 

 before the sitting, and described the mode of its formation. 

 From a Natterer compressing vessel a stream of liquid carbonic 

 acid was made to penetrate into a conical cloth bag. The basj 

 speedily got filled with a loose snow of carbonic acid, which 

 «as then, by means of a stamper, hammered together in a 

 cylindrical vessel into a solid cylinder. Compact carbonic acid 

 cylinders of this kind could be touched gently with the hand, 

 and possessed the hardness of chalk, which, tio, they resembled 

 in aopearance, and on account of their brittleness did not readily 

 admit of Ijeing cut with a knife. The specific gravity of .solid 

 hammered carbonic acid was found to be i'2.^Prof. Schw.albe 

 sh'iwed on a beech tuig the ice swellings he had described at 

 the last sitting. These were produced in a moderately freezing 

 mixture, tlieir formation failing in a strongly freezing mixture. 

 A twig which by way of experiment had been completely dried 

 entirely lost the capability it previously possessed in a high 

 degree of forming ice protuberances. — Prof. Erdmann related an 

 observation he had made some time ago, and had since very 

 frequently repeated. In a perfectly dark room he was able 

 only by indirect vision to perceive an object which reflected 

 li^hl very faintly, while, on endeavouring to look at it fixedly, 

 the object completely disappeared. This phenomenon he ob- 

 served only in the evening in going to bed, after he hid been 

 working for a considerable time in a brightly illuminated room. 

 On the other hand, when he awoke in the night he perceived the 

 faintly lucent object quite .as well by direct as by indirect vision. 

 Me was of opinion that this phenomenon was connected with 

 the lassitude of the middle parts of the retina, while Prof, von 

 Helmholtz explained it by the inferior sensitiveness to light of 

 tlie yellow spot in comparison with its surroundings. — Dr. 

 Rffiig reported at length the experiments which in common 

 v ith Ur. Dietrici he had instituted with a view to determining 

 the col Mr-sensitiveness of normal eyes. Exhibiting the appar- 

 atu . he had made use of. Dr. Kcenig explained its construction 

 and the procedure he had followed in the experiment. Towards 



one angle of a prism was directed an observing telescope, which, 

 instead of an eye-piece, had a diaphragm provided withasli', 

 on which the spectrum fell, so that it was possible to observe 

 sections of any degree of minuteness whatsoever. Tow.ards each 

 of the two other angles of the prism was placed a collimator, 

 which in the focus of its lens had a slit for the entrance of the 

 light, which was polarised by means of a Nicol prism. Behind 

 the slit was a double refracting pri^m, by varying the posi- 

 tion of which in the collimator the slit-image c juld be doubIe<l 

 at pleasure. Through the slit of the objective were seen close 

 beside each other the spectrum of the light which had passed 

 through one collimator, and the spectrum of light which had 

 passed through the other. While one collimator was now kept 

 fixed, the other, by means of micrometers, was displaced till the 

 point was reached at which the observer found the colours in 

 both spectra alike. The wave-lengths in both spectral stripes 

 were then measured, and their difference was the standard 

 of colour- sensitiveness in the single regions. For each wave- 

 length fifty readings were in this way made by each of the two 

 observers, and the mean difference calculated of the wave- 

 lengths in the two spectral ranges, which were perceived to be 

 equal. These experiments extended from the wave-length of 

 640 millionths of a millimetre to the wave-length of 430, and 

 were made from each 10 millionths of a millimetre, each pir- 

 ticular spot being ex.imined under two different intensities of 

 light. From the results of these measurements it was established 

 that the colour-sensitiveness of normal eyes ranged from more 

 than I to about o'2 millioiiths of a millimetre. The difference 

 of the D-linesin the .solar spectrum amounted to o'6 millionths 

 of a millimetre. Altogether three maxima of sensitiveness w ere 

 found. The first maximum appeared with the wave-length of 

 570 near the D-line. A second greater maximum approached 

 the F-line with a wave-length of about 490 to 470. Finally, a third 

 smaller maximum was found with a wave-length of 450 to 440. 

 The place of the maximum changed with the intensity in such a 

 manner that, the greater the in'ensity wa.s, the more the maxi- 

 mum shifted towards the more refrangible part of the spectnun. 

 Beyond the wave-lengths of 640 and 430 these experiments 

 could not be carried out, because, at the red end especially, no 

 differences of colour, but only differences of brightness, were 

 perceived. From the colour sensibility thus found, it was calcu- 

 lated that within the range of the normal spectrum the healthy 

 eye was able to perceive about 300 differences of colour. Dr. 

 Kcenig hoped to be able to set forth on a future occasion further 

 experiments in conjunction with the measurements here commu- 

 nicated, and the consequences resulting therefrom in respect of 

 the theory of the perception of colour. 



CONTENTS Page 



A Biological Laboratory on the English Coast . 473 

 The Unity of Nature. By George J. Romanes, 



F.R.S 474 



Our Book Shelf:— 



"The Electrician's Directory for 18S4'' 476 



Letters to the Editor :— 



On a "M.agnetic Sense." — Prof. W. F. Barrett . 476 



Instinct, — George J. Romanes, F.R.S 477 



The Remarkable Sunsets. — George J. Romanes, 



F.R.S 477 



Right-sidedness. — Henry T. Wharton ; Dr. John 



Rae, F.R.S 477 



Ravens in the United States. — Ira Sayles ; W. W. 



Bailey 47S 



Thread-twisting,— J. S 47S 



Bicycles and Tricycles, in Theory and in Practice. 



By C. Vernon Boys, A. R.S.M 47S 



Dangers from Flies 482 



Edinburgh Marine Station 4S3 



The Deep-Sea Fishes of the "Talisman" (IVilh 



Illustrations) 483 



Ancient Japan 485 



Notes 4S7 



Physical Notes 4S9 



The Chemical Work of Wohler. By Prof. Thorpe, 



F.R.S 4S9 



Meteoric Dust. By Lewis P. Muirhead 494 



University and Educational Intelligence 494 



Scientific Serials 494 



Societies and Academies 495 



