the present state of our acquaintance with the configuration of its surface, is not generally understood. When, however, the attention of astronomers is more generally directed to the study of the lunar surface, Science will he greatly the gainer, as it is there that the past and future of our earth is to be learned.
IN Les Mondes, January 20, 1876, appeared a list of the principal telescopes of the world, with their apertures and focal lengths. It was defective in regard to its enumeration of American telescopes, and in other respects, as all such lists must be. We have compiled from it, and from other sources available, a larger list, which is itself manifestly incomplete, but which will give a better idea of the number of telescopes available, or soon to be available, for astronomical purposes. It is a melancholy fact that the return from so many instruments, that is, the interest from so much astronomical capital, is not so great as it should be, and it suggests the question as to whether future benefactors of American colleges, for example, will not do better to provide astronomers to use the telescopes already constructed than observatories in which to put new ones. In the second column, the first name is that of the maker of the objective or speculum, the second that of the engineer who mounted the telescope.
|OWNER OR DIRECTOR,
|Constructed by||APERTURE.||FOCAL LENGTH.||Remarks|
|Lord Rosse, Birr Castle||Rosse||6 ft.||55 ft.|
|Wm. Herschel, Slough||W. Herschel||4 "||40 "||Out of use.|
|Lassell, Liverpool, etc.||Lassell||4 "||37 "||Destroyed.|
|Ellery, Melbourne||Grubb||4 "||32 "|
|Le Verrier, Paris||Martin, Eichens||1.20||7||Silvered glass|
|Lord Rosse, Birr Castle||Rosse||36 in.|
|Tisserand, Toulouse||Foucault||0.80||Silvered glass.|
|Stephan, Marseilles||Foucault, Ei-
|H. Draper, near N. York||H. Draper||28 in.||13 ft.||Silvered glass.|
|Lassell, Maidenhead||Lassell||24 "||20 "||Metal.|
|W. & J. Herschel, Slough
and Cape Good Hope
|W. & J. Herschel||15 "||Several mirrors.|
|H. Draper, near N. York||H. Draper||15 "|
|Maclean, Turnbridge Wells||With & Brown-
|Pritchard, Oxford||De la Rue||13 "||10 ft.|
|Worthington and Raven-
|With & Brown-
|Hirst, New Zealand||Browning||8½||Silvered glass.|
and many others.