The Transparency of Comets.

Two circulars recently issued by the Observatory describe the work being done on the accumulated photographic plates which has been made possible by the grant lately made by the Carnegie Institution and by record observations made by Professor O. C. Wendell in regard to the transparency of comets to stellar bodies. The plates under study have been made both at the Cambridge station and at the Observatory in Peru. From the observations made by Professor Wendell he disproves the statement that comets are perfectly transparent. In addition to data on these two subjects observations are recorded on missing asteroids, whose disappearance is regarded as a serious loss by astronomers.