542 



NATURE 



{April 7, 1 88 1 



sulphuric and nitric acid are added. Glycerine has an affinity 

 for water. A molecule of water is abstracted, and a molecule 

 of nitrous acid takes its place. Nitro-glycerine may be put into 

 the fire or it may be struck without any dangerous consequence. 

 If however it be set on fire by a fulminant, there is an e.xplosiuii. 

 If, as stated, the Russian bombs were made of filass, there must 

 have been small projections made in the glass shell when manu- 

 factured, filled with fulminating powder. The explosive cha- 

 racter arises from this : Nitrogen is composed of molecules in 

 pairs of atoms. Nitric acid contains only oue atom in its 

 molecules. Upon this atom being set free from its unslahle 

 combination in the glycerine, the two atoms of nitrogen ruth 

 together, producing a vast amount of energy of combiuation in 

 the shape of heat. The gaseous products are thus heated, and 

 an explosion takes place immediately." 



A School of Gardening and Practical Floriculture has been 

 established at the Crystal Palace, under the superintendence of 

 Mr. Edward Milner. 



M. Daudigny, electrical engineer in Paris, has sent to 

 the Municipal Council- a petition asking for authority to esta- 

 blish on the top of the Colonue de Juillct a large electric lamp 

 fed by a magneto-electric machine of fifty horte-power. This 

 enormous light is to be diffused by a large reflector of s; eci.il 

 construction. 



A MOST successful experiment in theatre illumination was 

 tried on March 30 and 31J at the Athenicum of the rue ues 

 Martyrs, Pari-, with the Werdermann incandescent light. The 

 peculiarity of it is that it can be graduated at will for scenic 

 effects, either by introducing resistance coils or varying the 

 velocity of the Gramme machine. These experiments were 

 witnessed by several influential members of the Municipal 

 Council, who on the following morning proposed au inquiry 

 into the propriety of obliging all the theatrical managers to light 

 their halls with electricity. 



Mr. F. W. Putnam sends us a paper on Pueblo Pottery, 

 which he contributed to the February number of 'i\\t Amci ican 

 Art Rcvie-^v. There are some well-executed coloured illustraiious 

 of specimens of the pottery which show some little taste in 

 colour and ornamentation. 



We have had several replies to our inquiry concerning the late 

 Dr. Ihomas Dick's astronomical instruments. They seem to 

 have been disposed of after his death, and only one small instru- 

 ment can be definitely traced. None of the in?truments seem to 

 have been of much scientific value. 



Mr. Johnston-Lavis writes, under date March 29 ;— 

 " Ve.-uvius is to-night again active, lava running do» n the north- 

 western slope of the cone. Only the reflection is vi-ible from 

 Naples. On Sunday morning a slight shock, or more correctly 

 subterranean thunder, v\ as felt at Casamicciola, although t ho- e 

 in the ruins at the moment only became aware of it by the pale r 

 of others present, whose whole attention is arrested by the 

 faintest move or noise." 



A Science Students' Association has been formed in Liverpool, 

 which includes all departments of science in its programme ; the 

 president is Mr. A. Norman Tate. 



The system of compressed-air clocks, of the use and construc- 

 tion of which in Paris we gave an account some time ago, is 

 likely to have a trial in London. A Bill h.as been introduced 

 into Parliament for this purpose. The number of stations 

 proposed for the metropolis is ten. 



In the notice of the meeting of the Mathematical Society in 

 Nature, vol. xxiii. p. 379, Mr. Wooiter Woodruff Beman's 

 name was misspelt Benson. 



Lieut.-Col. H. Collett, of Meean Meer, North-West 

 Punjab, has sent us a money-order for 3/. towards the John 

 Duncan Fund. We also acknow ledgereceipt of U. from M. G. S. 



The additions to the Zoological Society's Gardens during the 

 past week include a Two-Spotted Paradoxure (A'nKn'/w/r: binotata) 

 from West Africa, presented by Mr. A. Wentworth Forbes ; a 

 Golden Sparrow {Atiripasser cuchlorus) from Abyssinia, presented 

 by Mr. J. Abrahams ; a Chukar Partridge {Caciabis chukar), a 

 Grey Fraucolin {Francolinus fonticeriaiius) from India, presented 

 by M. J. M. Comely, C.M.Z.S. ; two Indian Antelopes {Antelope 

 cenicapra S 6 ) from India, deposited ; two .'Ethiopian Wart 

 Hogs {Phacocharus cethiopicus i 9 ) from South-East Africa, a 

 Dusky Parrut {Pionus violaceiis) from Guiana, three Ceylonese 

 Hanging Parrakeets (Lonctilus asiaticiis S i 9 ) from Ceylon, 

 a Yellow Troupial (Xanthosoma Jlavus) from Buenos Ayres, 

 purchased; a Fork- tailed Jungle Fowl (Callus fit rcattis i ) from 

 Java, on approval ; two Four-horned Antelopes ( Tetraceros 

 quadricornh (J 9 ), a Burrhel Wild Sheep (Ovis burrhel i ) from 

 India, a Javan Adjutant (Leploptiliis javanicus) from Java, a 

 Rock-hopper Penguin {Eudyptes chtysocome) from the Falkland 

 Islands, received in exchange. 



OUR ASTRONOMICAL COLUMN 



The Variable Stars U Cephei and U Geminorum. — 

 We learn from Mr. Knott that Ceraski's short-period variable 

 in Cepheus was at a minimum on March 29 at about I2h. 45m. 

 G. M.T. ; clouds prevented observations till iih. 3Sm. , when 

 it had barely fallen to minimum ; for two hours, iih. 45m. 

 — I3h. 45m., the star's light was sensibly constant — about 9'4m. 

 On April 3 Mr. Knott again obtained a pretty complete obser- 

 vation ; the time of minimum, taking the middle of the phase, 

 was I2h. 24m. G.M.T. ; for nearly 2h. 30m., or from iih. lom. 

 to I3h. 36m., the star remained about 9'4m. Guided by these 

 and previous observations the following apprcximate times of 

 minima are inferred, and it is to be hoped that the series may 

 be well observed : — 



Ap.il 8 



'3 



18 



12 4 

 II 43 



April 23 



28 



May 3 



May 8 

 13 



9 59 

 9 39 

 9 18 



This variable has been hitherto called T Cephei in this column, 

 but Mr. Knott draws attention to the circumstance that Ceraski 

 {Ail roil. iVac/i., No. 2343) applied that designation last October 

 to another variable discovered by him, the position of which by 

 meridian observations at Moscow was found to be in R.A. 

 2ih. 7m. 57'05s., Decl. + 68° o' 8"'4 for i8So'o, and we 

 accordingly follow his suggestion that the short-period variable 

 will be more properly termed U Cephei. 



U Geminorum was observed by Mr. Knott at about the 

 maximum, or abuut 9"3m., on April 2 and 3. Maxima of this 

 very irregular variable star are by no means easy to catch. It 

 precedes the principal component of 5 1 158 by Im. 26 '55 , and 

 is north of it 7' 31". Prof. Winnecke gave a series of com- 

 parison stars in Astron. Nach., No. 1120. Argelander's position 

 for 1855 is R.A. 7h. 46m. 29-8Ss. ; Deck -f 22° 22'4l";S. 



While writing upon variable stiirs we may mention that 

 B.A.C. 4767 is probably to be included amcmg them. It 

 was estimated 4m. by D'Agelet on May 15, 1783 ; it is called 

 6m. by Lacaille, Lalande, and Piazzi, and was so estnnated in 

 Argelander's Zone, No. 301 ; but although rated 5-7 in the 

 Uranoiiictria Argentina it is not feund in Heis's Atlas nor in the 

 Uranometria of Argelander. Its place for the present year is in 

 R.A. I4h. l8m. is., with south declination, 24° I5''6. 



The Comet of 1S12. — Several years since, Mr. W. E. 

 Pluramer of the University Observatory, Oxford, after a new 

 reduction of the observations made at Paiis and Viviers, which 

 we possess in their original form, found the period of revolution 

 about I5 years le>s than that given by Encke, so that it is quite 

 pcstible that the comet may arrive again at perihcliim within the 

 present year. We have already mentimed that M. Schulhof of 

 Paris is engaged upun a strict investigation of the elements of 

 this comet, and has the i.itention of pre] aring extended epheme- 

 rides, in the same manner that he has done for several of the 

 minor planets which had not been observed nt several opposi- 

 tion«, but the sweeping lines for every fourth day throughout 

 the year are given in Herr Mahn's ephemeris comi-uted on the 

 suggestion of Prof. Winnecke, which will be found in the 

 Vierteljahrsschrift der Astronomisclten Ceselhchaft, 12 Jahrgang. 



