Local System and Draper Extension 75
this indicates that the obscuring cloud is not completely
opaque, but merely cuts down the light of the more distant
stars by two or three magnitudes.
The obscuring nebulosity of the Taurus region extends
northward and westward for many degrees, beyond the
graphic magnitudes.
limits of the plots here given. In order to investigate fur-
ther its extent and its distance from the Sun, the Henry
Draper Extension is being spread over the whole region
affected. When the material is available we shall be able
to consider thoroughly the position of the Taurus nebulosity;
and perhaps by making special spectroscopic studies of the
various classes of stars in or beyond the nebulosity we may
be able to learn more concerning the nature of the ma-
terials of which such cosmic clouds are composed.