Page:In the high heavens.djvu/56



N a visit to Cambridge, Professor E. E. Barnard, the discoverer of the fifth satellite of Jupiter, exhibited at the Cavendish Laboratory a most interesting collection of photographs made at the Lick Observatory. These pictures were obtained by a six-inch photographic lens of three-feet focus, attached to an ordinary equatorial, the telescope of which was used as a guider when it was desired to obtain a picture of the stars with a long exposure. Among the advantages of this process may be reckoned the large field that is thereby obtained, many of the plates that he exhibited containing as much as sixteen square degrees. I am, however, not now going to speak of Barnard's marvellous views of the Milky Way, nor of the plate on which a comet was discovered, nor of the vicissitudes of Holme's comet, nor of that wonderful picture in which Swift's comet actually appears to be producing, by a process of gemmation, an offshoot which is evidently adapted for