Of 



24 Notes and Memoranda. 



This phenomenon only occurs when the combustion is vivid. When the metal 

 begins to burn the ray D shines on a black ground ; as the combustion becomes 

 more active it developes in one part and another of the ray D, which it enfeebles, 

 intense rays, which at first do not pass beyond its immediate vicinity, but which 

 rapidly invade the whole expanse of the spectrum with ordinary tints as the sodium 

 becomes completely on fire ; and at last there is observed only the rays of the dou- 

 ble ray D which detaches itself in intense black — that is to say, with the same ap- 

 pearance as in the spectrum formed with the light which emanates from the sun." 

 Trepidation op the Soil at Nice. — From a letter by M. Prost to M. Elie 

 de Beaumont, published in Comptes Hendus, we learn that, during the late erup- 

 tion of Vesuvius, tremblings of the ground occurred at Nice, varying suddenly in 

 force and direction. 



The Companion op Sirius. — Mr. Clark of Cambridge, U.S., has discovered, 

 and Mr. Bond has verified, the existence of a companion of Sinus, distant 10''. 

 It had been suspected by Bessel and Peters, on account of certain periodical per- 

 turbations in the right ascensions of the great star, and was conjectured to be a 

 dark body, as it could not be found before Mr. Clark's fortunate observation with 

 an 18-inch instrument. The companion of Sirius has been seen at Paris (since 

 its discovery in America) with M. Foucault's large telescope, with a silvered 

 mirror, 80 centimetres. It is visible only when atmospheric conditions diminish 

 the radiation from the great star. Mr. Peters has written to Cosmos, stating that 

 it cannot be identified with the body whose existence he suspects. The exact dis- 

 tance of the little star is 10" "5, angle of position, 85°. 



Carbon and Hydrogen. — M. Berthelot, who has been long engaged in forming 

 hydro-carbons by a synthetical process, has recently made a remarkable experiment 

 by passing a current of hydrogen between the charcoal points of a Biinsen's battery 

 of 60 elements. At this extreme temperature the hydrogen combined with the car- 

 bon producing a cetyline. The facts were communicated to the French Academy 

 by M. Balard on the 17th March. 



Yocal Fishes. — Dr. Dufosse communicates to the French Academy farther 

 researches into the vocal powers of certain fish, most of his observations being 

 made upon species of Trigla and Zeus (gurnards and dories). He states the 

 sounds to be produced by the vibration of the muscles belonging to the air- 

 bladder, and that large gurnards may be heard at a distance of six or seven 

 yards. Out of five or six hundred individuals of the species mentioned, their 

 voices were comprised between si 2 and re 5 inclusive. The sounds were instan- 

 taneous, or prolonged for several minutes, sometimes as long as seven or eight 

 minutes. The pitch often varies during a single " sonorous emission." The 

 finest vocal performers appear to belong to the species Morrttde, who surpass all 

 their congeners in producing a great number of completely distinct sounds. 

 "They sustain the simple sounds better, and modulate better the compound 

 sounds ; they render more distinctly long successions of sounds different in tone 

 and pitch ; in fine, there is less dissonance in the sonorous vibrations they pro- 

 duce. Other species, however, beat them in intensity. 



Microscopic Writing. — The President of the Microscopic Society of London 

 stated in his annual address that the beautiful machine presented by Mr. Peters 

 has enabled the Lord's Prayer to be written in the 356,000th of a square inch — a 

 space like a minute dot. The English Bible contains 3,566,480 letters. The 

 Lord's Prayer, ending with "Deliver us from evil," 223 letters ; so that the Bible 

 is 15,992 times longer than the prayer, and if we employ round numbers we may 

 say it could be written in 16,000 times the space occupied by the prayer, or in less 

 than the twenty-second part of a square inch. In other words, the whole Bible 

 might be written twenty-two times in one square inch. This wonderfully minute 

 writing is clearly legible when placed under a good microscope. In using the 

 machine the operator writes with a pencil attached to one end of a long lever ; 

 whatever marks he makes on a piece of paper are infinilesimally reduced in corre- 

 sponding motions, by which a glass plate is moved over a minute diamond point. 

 By means of Ibbctson's geometric chuck, beautiful geometric designs may bo 

 engraved on a similar scale of minuteness. 





