NOTES. 



719 



aa engineer, Alessandro Giordano, called 

 attention to the danger of extending these 

 excavations farther toward the city. Add 

 to this the action of the carbonic waters of 

 the thermal springs in hollowing out caverns 

 in the trachytic rocks, and we have probable 

 a condition of the subsoil and underlying 

 formations extremely perilous to the stabil- 

 ity of the foundations of the town, and one 

 under which just such a disaster as has 

 overtaken it might be readily conceivable. 



M. Wrodlewski has been investigating 

 the boiling-points of air, oxygen, nitrogen, 

 and carbonic oxide, at the ordinary press- 

 ure of the atmosphere, and fixes them as 

 follows : Oxygen, 299° Fahr. ; atmospheric 

 air, SU"; nitrogen, 31 5'5° ; carbonic oxide, 

 3I4"4°. Atmospheric air seems destined to 

 be the refrigerant of the future, for it is 

 already at hand, and will produce a degree 

 of cold that is only insignificantly exceeded 

 by that induced by any other substance. It 

 must, of course, be first compressed and 

 liquefied ; then, when it is to be used, it will 

 be let loose to freeze by its evaporation, as 

 is now done with other refrigerants operat- 

 ing in a similar way. 



M. GcsTAVE Hermite describes a method 

 of taking phosphorescent photographs, which 

 he has found to be practicable with any 

 phosphorescent substance, but for which he 

 prefers sulphuret of calcium, a material 

 from which a luminous paint is made. This 

 substance is very sensitive to light, and 

 assumes a phosphorescence the intensity of 

 which is proportioned to the intensity of 

 the light to which it is exposed, rather than 

 to the length of the exposure. A glass 

 plate is painted with it, and is exposed in a 

 bright light in the face of the object of 

 which a picture is desired. The picture 

 appears very distinct when the plate is 

 taken into the dark. It may be revived 

 afterward by breathing upon the plate, and 

 then passing a hot flat-iron over it. Sul- 

 phuret of calcium becomes phosphorescent 

 under the influence of heat (300° C.) as 

 well as of light. 



M. E. L. TnorvELOT has concluded, from 

 observations on the planet Saturn for sev- 

 eral years, that his rings are not fixed but 

 very variable ; and that the hypothesis that 



they are composed of multitudes of cor- 

 puscles or minute satellites, revolving in 

 independent orbits, is very probable, and 

 affords the best explanation of the phe- 

 nomena. 



NOTES. 



Dr. Austin Flint is quoted in the seven- 

 teenth report of the Peabody Museum as au- 

 thority for the statement that the metalcs, 

 or grinding-stones, used in Nicaragua, are 

 obtained from the old burial-mounds. Dr. 

 Flint informs us that this is true, so far 

 as the northwestern departments of Costa 

 Rica are concerned, but that the idea of the 

 same being the case in Nicaragua is an er- 

 ror, arising from an inaccuracy of his own 

 expression incidentally committed in writ- 

 ing hurriedly on another subject. The me- 

 iates in universal use in Nicaragua are made 

 there now, and are much inferior to those 

 found in the mounds ; and, being of much 

 less value, they are gradually being bought 

 in Costa Ilica. 



The biological class at the University of 

 Cambridge has outgrown the capacity of any 

 lecture-room to accommodate it, and at the 

 last term numbered two hundred in the ele- 

 mentary department alone. A consideiVble 

 number of graduates remain at the univer- 

 sity engaged in biological research, and the 

 museums are continually being enriched 

 with specimens presented by recent gradu- 

 ates who are traveling on scientific expedi- 

 tions. 



General Sir Edward Sabine, for ten 

 years President of the Royal Society, and for 

 twenty years General Secretary of the British 

 Association, recently died at Richmond, Eng- 

 land, aged ninety-four years. After serving 

 on the English side in the war which we call 

 the War of 18 1 2, he became officially engaged 

 in scientific work, and served his govern- 

 ment and the scientific associations for twen- 

 ty years in astronomical and magnetic in- 

 vestigations, in the course of which he was 

 connected with several Arctic and marine 

 expeditions. He was elected General Secre- 

 tary of the British Association in 1839, For- 

 eign Secretary of the Royal Society in 1846, 

 and Vice-President and Treasurer of the 

 same in 1850; and was President of the 

 Royal Society from 1861 to 1871. Our pres- 

 ent conception of the exact figure of the 

 earth is said to be mainly due to his inves- 

 tigations. A portrait and sketch of General 

 Sabine were published in the second number 

 of Vol. II of " The Popular Science Monthly." 



M. Pasteur, in consideration of his re- 

 searches in hydrophobia, has been awarded 

 a gold medal by the French SociHe Centrale 

 I jiour V Amelioration des Races des Chicns. 



