n 1888 the two chief spiral and other nebulae.[1551]
Photographs of the Lyra nebula taken at Algiers in 1890,[1552] and at
the Vatican observatory in 1892,[1553] were remarkable for the strong
development of a central star, difficult of telescopic discernment, but
evidently of primary importance to the annular structure around.

The uses of photography in celestial investigations become every year
more manifold and more apparent. The earliest chemical star-pictures
were those of Castor and Vega, obtained with the Cambridge refractor in
1850 by Whipple of Boston under the direction of W. C. Bond. Double-star
photography was inaugurated under the auspices of G. P. Bond, April 27,
1857, with an impression, obtained in eight seconds, of Mizar, the
middle star in the handle of the Plough. A series of measures from
sixty-two similar images gave the distance and position-angle of its
companion with about the same accuracy attainable by ordinary
micrometrical operations; and the method and upshot of these novel
experiments were described in three papers remarkably forecasting the
purposes to be served by stellar photography.[1554] The matter next fell
into the able hands of Rutherfurd, who completed in 1864 a fine object
glass (of 11-1/2 inches) corrected for the ultra-violet rays,
consequently useless for visual purposes. The sacrifice was recompensed
by conspicuous success. A set of measurements from his photographs of
nearly fifty stars in the Pleiades, and their comparison with Bessel's
places, enabled Dr. Gould to announce, in 1866, that during the
intervening third of a century no changes of importance had occurred in
their relative positions.[1555] And Mr. Harold Jacoby[1556] similarly
ascertained the fixity of seventy-five of Rutherfurd's Atlantids,
between the epoch 1873 and that of Dr. Elkin's heliometric triangulation
of the cluster in 1886,[1557] extending the interval to twenty-seven
years by subsequent comparisons with plates taken at Lick, September 27,
1900.[1558] Positive, however, as well as negative results have ensued
from the application of modern methods to that antique group.

On October 19, 1859, Wilhelm Tempel, a Saxon peasant by origin, later a
skilled engraver, discovered with a small telescope, bought out of his
scanty savings, an elliptical nebulosity, stretching far to the
southward from the star Merope. It attracted the attention of many
observers, but was so often missed, owing to its extreme sus