FULGURITES—NEW SOUTH WALES. ay id 
allite and anorthite, that there was a deficiency of about 1:7, equal 
to ‘9 per cent., of soda. Adding this in accordance with Mr. Stone’s 
note, and recalculating back into percentages, the analysis closed 
with + ‘12 per cent. of silica and — ‘5 per cent. of alumina. 
This calculation gave me a result of 84:10 per cent. of albite 
and 16:73 per cent. of anorthite as the composition of the felspar 
or ab. 5 to an. 1. 
According to a table given by Dana (Min. 1892, p. 327) the 
percentages thus found are about 3 per cent. too high as regards 
the alkaline constituent. 
The comparison of the optical and chemical examinations 
leaves the exact composition of this oligoclase in doubt in so 
far as relates to it being nearer to allite or to anorthite by one 
proportion of the former. But for all practical purposes, the 
observations of the obscuration angles, and of the position of the 
optic axial plane, appear to be sufficiently accurate to serve as a 
grade in diagnosing the character of a felspar observed in a thin 
slice of rock of the group to which the lavas of Mount Anakies 
belong. 
No. 14.—NOTE ON THE OCCURRENCE OF FULGURITES 
IN THESAND-HILLS AT KENSINGTON AND BONDI 
IN NEW SOUTH WALES: WITH A BIBLIOGRAPHY 
OF FULGURITES. 
By G. H. Kyisss, F.R.A.8.; J. W. Grimsuaw, M. Inst. C.E.; 
and Rev. J. M. Curran. 
(Read Tuesday, January 11, 1898.) 
Futeurires, lightning tubes, or ceraunic sinters (Fr. fulgurites, 
pierres foudroyées ; Ger. Fulguriten, Blitzrshren, Blitzsinter), as 
their name implies, are fused tubes or other fused structures, 
produced in sand, earth, or in rocks, by the action of lightning. 
They seem to have been first noticed by Pastor Hermann, of 
Massel,’ Silesia, who, however, erred as to their origin, since he 
failed to recognise that the fusion was due to lightning. It was, 
notwithstanding, early known that lightning causes fusion, as 
the papers of de Fischer,? Buchholz,* Tillet and Desmarest,‘ and 
Alleon Dulae® indicate; and, in his papers on lightning and 
lightning conductors, Reimarus® mentions that the points of 
conductors occasionally melted during storms. In his Alpine 
travels between 1768 and 1789, Saussure’ found small blackish 
