April 13, 1893] 



NATURE 



565 



closing a small hole in the observing tube by a plate of aluminium 

 o'oo3 mm. thick, it was possible to study their -properties out- 

 side the tube. It was found that the rays produce a slight 

 luminosity in air, and when they fall on phosphorescent bodies, 

 held near the window, cause the latter to shine with the same 

 light they show when enclosed within the vacuum tube itself. 

 The brightness diminishes rapidly as the distance from the 

 window increases, so that in air all glow ceases at about 6 cm. 

 On bringing a magnet near the tube so that the kathode rays 

 no longer fall on the inner surface of the window, all phosphor- 

 escence ceases without the tube. A quartz plate half a milli- 

 metre thick entirely stopped the rays ; ;ordinary gold, copper, 

 and aluminium leaf, however, allowed them to pass almost un- 

 diminished. In air at the ordinary pressure these ra)s are not 

 propagated in straight lines but are diffused, so that it is im- 

 possible to obtain a sharp shadow of a body placed between the 

 window and the phosphorescent substance. As these waves 

 cannot be generated in a high vacuum it has been up to now 

 impossible to say whether they are only propagated when matter 

 is present. By enclosing the observing tube in another, the 

 author has shown that in the best vacuum attainable with a 

 mercury pump, these waves are transmitted with as great facility 

 as in air at the pressures ordinarily existing within Geissler 

 tubes. Different gases transmit the rays to very different ex- 

 tents, thus, with hydrogen at atmospheric pressure, phosphor- 

 escence is produced in a body placed at a distance of 20 cm. 

 from the window. These experiments seem to show that while 

 for light of the smallest known wave-length the matter behaves 

 as if it completely filled the space it appears to occupy, in the 

 case of these kathode rays even gases behave as non -homogeneous 

 media, and each separate molecule acts as an obstacle diffusing 

 the rays. 



Notes from the Marine Biological Station, Plymouth : — 

 Recent captures include the Polyclada Etirylepta cornuta, 

 Cyclcporus papillosus and Leptoplana, the Actinian Zoanthus 

 Couchii, and the Opisthobranchs Scaphander lignarius and 

 Aigirus pumlilucens. The sea has lately become increasingly 

 richer in diatoms and floating algae, esp. Coscinodiscus, Rhizose- 

 tenia and the so-called "gelatinous alga." In the floating 

 fauna the Dinoflagellate Ceratium tripos has been constantly 

 plentiful^ throughout the winter ; Noctiluca is very scarce. Of 

 the Hydroid meduste, small Obelicc are still abundant ; medusee 

 of Ctytia Johnstoni are generally present ; and Forbes's Thau- 

 maniias octoiia has been again observed. The Actinian larva 

 Arachnactis occurs in most townettings. Zoseae of Porcellana 

 have slightly increased in number. The Actinian Bunodes 

 verrucosa (= f^eininacea) is now breeding. 



The additions to the Zoological Society's Gardens during the 

 past week include a Leopard i^Fetis pardtis) from India, pre- 

 sented by Admiral W. B. Kennedy, R.N., F.Z.S. ; a Common 

 Squirrel (Sciurus vtitgaris) British, presented by Miss Edith 

 Mackenzie ; two Black Rats {Mus rattus) British, presented by 

 Mr. Sydney Wedlock; a Panama Amazon [Chrysotis pana- 

 mensis) from Panama, presented by Mrs. Mackey ; a European 

 Pond Tortoise (Emys eiiropcea) European, presented by Mast, 

 J. F. Harben ; a Macaque Monkey {Macaais cynomotgus) from 

 India, deposited ; a Common Pintail {Dafila acuta) European, 

 a Bell's Cinixys {Cinixys beltiana), a Home's Cinixys {Cinixys 

 hoineana) from West Africa, purchased ; a Mute Swan (CTy^g'w/w 

 otor) European, received in exchange ; three Coypus {Myopo- 

 tamus coypus) born in the Gardens. 



OUR ASTRONOMICAL COLUMN. 

 Solar Observations at Ro.vie. — In the Meniorie degli 

 Spettroscopisti Italiani for March, Prof Tacchini communicates 

 the solar observations made at the Royal College. These obser- 



NO. 1224, VOL. 47] 



vations refer to the 4th trimestre of 1892, and are given here 



somewhat in detail. Taking prominences first, the numbers 

 show a great falling off when compared with the preceding 

 three months ; thus for the northern and southern hemispheres 

 the frequency of these phenomena for the three months was 

 81, 78, 61 for the former (sum 220) and 105, 138, 90, for the 

 latter (sum 333) the foregoing trimestre giving 431 and 493 for each 

 hemisphere. The greatest freciuencies took place in latitudes 

 + 60° -f 70° N. and - 30^ - 40° S., but the numbers indicate 

 really two other maxima for each hemisphere, and they lie in 

 the zones -I- 30° -f 20° and - 50° - 60 . 



The frequency of groups of faculae recorded for both north and 

 south latitudes are given as 100 and 132 respectively ; the 

 average for each month amounted to 37, but for the southern 

 zones during October an increase to 20 above this average was 

 noted ; the greatest frequencies occurred in zones + 10" -f 20° 

 and - 20° - 30°. In dealing with the spots their frequency 

 may be generally stated to be about half that of the faculae. 

 The table gives 46 and 58 for the two zones, and in this case 

 also the greatest disturbances seem to have occurred in the 

 southern hemisphere during October ; the numbers for the 

 monthly records are, for the northern zones 18, 13 and 15, and 

 for the southern 26, 12, and 20, the greatest frequencies occur- 

 ing in latitudes + 10° 4- 20'"' N. and - 20° - 30" S. 



Prof. Tacchini, in addition to the above communication, de- 

 scribes in a short note a large protuberance observed on No- 

 vember 20 of last year, and gives 10 figures to illustrate the 

 various forms which it successively assumed. The height and 

 velocity of ascent can be gathered from the few numbers 

 below : — 



„ II. M. 



146-3 about 10 57 



1555 „ II 225 



1888 „ I 21 



1841 „ I 58 



1864 ,, 2 38 



154-6 ,, 2 52 



Parallaxes of /* and Q Cassiopei.e. — In No, 5 of the 

 contributions from the Observatory of Columbia College, New 

 York, Mr. Harold Jacoby presents us with the results he has 

 obtained with regard to the parallaxes of /x and Cassiopeise, 

 as deduced by him from an examination of the Rutherfurd 

 photographic measures of the stars surrounding /< Cassiopeia;. 

 The negatives, which were twenty-eight in number, two impres- 

 sions being on each plate, were made between July, 1870, and 

 December, 1873, and as they were specially taken for parallax 

 determinations, the observations were restricted to the months 

 of July, January, and December. The study of the parallax 

 here made is based upon measures of distance only. Each pair of 

 stars was selected so as to differ approximately 180° in position 

 angle with respect to fx Cassiopeiae, and the scale value was 

 determined for each pair, on each plate, in order to make the sum 

 of the distances from ju constant. By taking the difference of 

 the same distances as the quantity from the variation of which 

 the parallax should appear, "the excess of the parallax of the 

 principal star over the mean of the parallaxes of the two com- 

 parison stars" is, satisfying certain conditions, finally obtained. 



The values for the parallaxes which he has obtained are — 



Parallax of ii Cassiopeiae 

 ., 



o'275 ± 0024 

 0*232 ± 0-067 



On comparing the former of these values with the work of 

 other observatories the discordances, he says, are large. The 

 Oxford photographic result was o"o36 ± o"oi8, while the 

 Rutherfurd plates gave o"249 ± o"o45, the same pair of com- 

 parison stars being used in each case. Struve from distant 

 measures deduced the value o'-25i ± o" 075, and from position 

 angles the value o" -425 ± o"-072. " It is therefore plain that 

 the photographic method of determining parallaxes cannot be 

 regarded as free from systematic error." 



Fam, ok a Meteorite. — A brief account of the fall of a 

 meteorite at a place in South D.-ikota, 4 km. south of Bath, on 

 August 29 of last year, is given in the cut rent number of 

 Prometheus, No. 183. It was observed about four o'clock in 

 the afternoon, attention being first drawn to it by the sound of 

 a series of explosions. As the observer looked upwards he saw 

 a meteoritic stone flying through the air, leaving a trail of 

 smoke behind it. On reaching the ground it plunged to a depth 



