Chemistry and Physics. 461 
The following table contains the numbers obtained for the 
principal lines and bands. These numbers appear exact to within 
one or two millionths of a millimeter, and may be substituted 
for those which have been given in the publications of my previous 
researches. 
Wave-lengths of the hag! lines and bands in the infra-red Yt of the solar spec- 
expressed in millionths of a millime 
7004. A, [ i oup of two 
771. bands which appear 
ee “ ae to be those indicated 
791 to 796 : by Capt. Abney 
4, o: ani 
819. (Sodium), 1142. (Sodium). 
830. . 1200. (Magnesium). 
844, 1254. a aoe 
Corresponds to a calcium Border inet 
S88: 0-860 | rong: from 1351. Ap- 
. 1354 to 1400. A’, pears to be the 
898 to 900. (Magnesium). band named » 
917 to 920. Band or group of lines. by Abney. 
934 to 945. { A’. Group of lines and} 1440. Feeble band. 
950 to 965. bands very near to one | 1510 to 1560. Group of ban 
968. (> another. 
proximatenum- 
992. bers. This band 
1025, 1800 to 1880. Atv, has been called 
1069 to 1075. @ by Mr. Lang- 
ley. 
The above results show that the phosphorographic method per- 
mits, hosphorescent substances are properly. he . 
the investigation of the i red part of the spectrum as 
mass fovther and farther than reap meth This mastiod 
Nov., 18 ie 
12, On the Strain connected with say “ggg i and with the 
Pesala of perlitic structure—Mr. Frank Rutiey has dine 
Quart. Journ. Geol. Soc., July, 1884) some ae resting obse 
tions on the effe ct of incipient crystallization and the develo pone! 
of the perlitic structure in producing a state of strain in some 
vitreous rocks, as shown by the phenomena observed in polarized 
light. The observations were made upon a section of obsidian 
from Japan. This showed a considerable number of crystals 
under the microscope and about each of them the a pone 
ena occurring within the re toe ee or again there may be 
crystals surrounded by the strained and these areas bound 
