Summer Work at the Observatory.

During the summer vacation, the astronomers at the observatory have been by no means idle, but even harder at work than in the winter. The most interesting piece of news from this department is the generous gift of $50,000, by Miss C. W. Bruce, of New York, for a photographic telescope. The instrument will be made with a double lens, a new form not yet adopted by European astronomers, but considered by Professor Pickering far superior to single lens telescopes. It will have an aperture of twenty-four inches. Its focal length will be short, and consequently it will include a large area of the sky at once, and will also obtain images of very faint stars and nebulae. With this telescope, Professor Pickering expects to accomplish as much as seventeen other observatories working together according to a plan recently matured at Paris. The lenses will require almost as much metal and as much time and care in construction as the great Lick lens. The contracts have been awarded to the manufacturers of the Lick lens, and it is expected to be finished in about two years. A similar telescope with a diameter of eight inches, is now being used at the station of the Harvard observatory in Peru. Over eight hundred photographs have been taken with it and sent to Cambridge. Another eight-inch lens has just been received here for use until the Bruce lenz is completed.

The work at the observatory this summer has consisted chiefly in photographing spectra of stars with an eleven inch refracting telescope, and in experimenting with several new instruments. Among others, a fifteen-inch reflecting telescope, made and presented by the late Henry Draper, is worthy of mention. It is now being used for photographing stars.