1883 .] Correspondence. 433 
in doors or shutters, have been accounted for by the hypothesis 
of Cosmic dust, which, as is said, pervades space, and conse- 
quently our atmosphere. If in England, then, also in Borneo. 
As a matter of faCt, however, no such visible lines of illuminated 
dust are observed here. The houses of at least half the inha- 
bitants of Borneo are built by the sides of rivers, on muddy 
banks, surrounded by forest. They are constructed of wood, the 
flooring generally quite 20 feet above the ground (Swiss lake 
dwellings), more often 40, and the walls and roofs are made of 
leaves of palms. It naturally enough often happens, especially 
after a blow, that apertures larger or smaller are made in the 
roof. The sun and sky may be seen through these apertures, 
and upon the floor may be observed a corresponding circle or 
oval of light, according to the time of day ; but no connecting 
illuminated line. When one blows the smoke of a cigarette 
across the line of connection, that becomes at once illuminated. 
Therefore the theory of Cosmic dust should perhaps be no longer 
entertained. 
And here occurs to me a query. How many of Mr. Editor’s 
molecules would go to make up a particle of this Cosmic dust 
made visible to us by a line of light traversing a comparative 
darkened chamber ? And again, How much of the sun’s light 
and heat should we enjoy were space filled with such gross stuff? 
— I am, &c., 
01 . de Crespigny. 
