446 report— 1878. 



Au contraire, a, l'epoque ou les phenomenes extraphotospheriques se calnient et 

 presentent leur minimum (Taction, le milieu coronal peut reprendre une figure 

 relativement plus reguliere et se rapproclier davantage des conditions d'ime atmo- 

 sphere en equilibre. 



Si nous possesions des dessins tres exacts de la figure de la couronne pendant 

 les eclipses totales des derniers siecles, il serait bien interessant de les etudier a ce 

 point de vue. 



Mallieureusement les descriptions et les dessins que nous poss^dons ne sont 

 gendralenient pas assez fideles ni assez prdcis pour servir tres utilement a cet objet. 



Cependant on peut considerer comme confirmaut l'idee e'mise, les observations 

 precises de l'eclipse de 1842 analysees par Arago. On voit en effet que la couronne 

 etait alors formee d'anneaux concentriques nettement terminees, ce qui indique un 

 6tat relatif d'equilibre. Or, l'annee 1842 6tait une epoque de minimum. 



En 1871, la couronne presentait au contraire un aspect tres tourmente que j'ai 

 decrit dans mon memoire. Et cette annee etait line epoque de maximum. 



Ajoutons maintenant que la couronne pendant la derniere eclipse de Juillet 

 1878, d'apres les premieres relations publiees, aurait <5te trouvee tres basse et d'un 

 aspect tout different de celui de 1870 et 1871. Nous sommes encore dans la 

 periode minimum, puisque les taches solaires sont encore actuellement si rares, cette 

 observation semble done confirmer encore l'idde que nous avons e"niise dans le 

 memoire de 1871 et developpee au Oongres de Glasgow. 



Nous comptons revenir sur ce point, mais nous devons faire remarquer que si 

 pour nous, l'aspect et la constitution de la couronne sont en dependance 

 avec les phenomenes protuberantiels, il ne faut pas oublier cependant que la 

 couronne peut encore emprunter une partie de ses aspects a des matieres cosmiques 

 circulant autour du soleil dans ces regions, et venant compliquer ainsi les apparences 

 de l'atmosphere coronale. 



10. On a Neiv Form of Receiving Instrument for Microphone. By W. J. 

 Millar, C.E., Sec. Inst. Engineers and Shipbuilders in Scotland. 



Tbe author, having been engaged in experiments upon the transmission of sound 

 by wires without the aid of electricity or magnetism, had his attention more 

 particularly directed to the connection between the strains produced in the bodies 

 experimented upon and the sounds emitted. These experiments having been 

 carried out with copper wires, it occurred to the author, after the announcement of 

 the Microphone of Professor Hughes, that, since a magnetic needle, arranged as a 

 galvanometer, has certain definite motions due to the flow of the electric current, 

 then if the needle -wereflxed, instead of moving it would be thrown into a state of 

 strain, and it would then give out sounds corresponding to the changing condition 

 of the current. To test this, a few yards of covered copper wire were passed 

 lengthwise, in galvanometer fashion, along a small bar magnet ; sounds were imme- 

 diately detected on breaking contact, when the magnet was pressed to the ear. 

 These sounds were much re-inforced by placing the magnet against the shallow lid 

 of a pasteboard box, or by placing it on a piece of tin. 



A horse-shoe magnet with two or three yards of the same wire (about No. 30) 

 laid lengthwise along one of its limbs, and with the lid of a tin box placed on the 

 flat sides of the ends of the magnet, made an excellent receiver — speaking, singing, 

 &c, being easily rendered audible. 



A small form of receiver was exhibited by the author at the meeting, consisting 

 of a bar magnet 3 inches long, ~ inches broad, and about ^ inches thick. About 

 6 yards of No. 30 covered copper wire are passed backwards and forwards length wise 

 along the magnet, galvanometer fashion ; the magnet is placed in a shallow paste- 

 board box, and a couple of pieces of tin are laid above and below the magnet (as 

 this appeared to still further strengthen the sounds) ; the lid is then placed on, and 

 the whole is thus rendered an easily portable pocket instrument. With this instru- 

 ment, speaking, singing, whistling, besides other Microphone phenomena, are readily 

 obtained. A single Leclancbi cell, weakly charged, was used ; a rough form of 



