are shown in the reproduced photograph of the station. In this camera the Clark lens of 5-inch aperture, the combination tube of iron and cloth, and the plate-carriage moving by clockwork on an accurately curved metal track, are supported entirely independently of each other. The lens is mounted on the top of a strong interior tower, surrounded by a cloth-covered outer tower, whose duties are to support the upper end of the camera tube and to prevent the wind from shaking the inner tower; a system of lens support devised by Mr. CAMPBELL to meet conditions on the plains of India in 1898. With this form of support the camera can easily be pointed near the zenith if necessary (as in Sumatra by Mr. PERRINE in 1901); and the advantage of having the lens at a good height above the radiating soil is preserved. The towers are easily constructed, the various parts of the camera are quickly put into their approximate positions from simple computations, and the final adjustments are readily made.

The Sun's altitude at Alhama was 55°, and the center of the lens was 32 feet 8 inches €9.96 meters above the center

of the photographic plate.

Ten exposures were made on Seed No. 27 plates, as follows:

The two 64-second exposures were on plates 18 X 22 inches, and the other exposures on plates 14 X 17 inches. Plates Nos. 4, 5, and 9 had "standard square standard square" exposures made near one corner of each of them at Mt. Hamilton in May by means of a Hefner amyl-acetate lamp, kindly loaned for the purpose by the Department of Physics of the University of California.

GENERAL VIEW OF THE LICK OBSERVATORY-CROCKER ECLIPSE EXPEDITION, ALHAMA, SPAIN.

These squares are intended as a basis for a photometric study of the coronal images.

When the negatives were developed we were relieved to find that the clouds had exerted no bad effects upon their quality the obscuration had simply reduced the effective coronal intensity without spoiling the definition. The "seeing" had been good, and the negatives were of great excellence. The longer coronal streamers were recorded out to about one solar diameter from the Sun's edge. The details of the great prominences on the eastern limb, of a few of the smaller prominences, of the coronal arches over the prominences, and of the coronal structure are of great interest. The streamers were, in general, of substantially equal lengths at all points of the solar limb. Those of more than average lengths seemed not to be specially related to the great streamers visible at times of sun-spot minima. The present corona was a "maximum" one. An attempt has been made to reproduce one of the one-second negatives by heliogravure process, in the accompanying illustration. The great prominence is shown, though with serious loss. in sharpness, but the rich details of coronal structure are completely lost. It seems impossible to reproduce coronas by mechanical processes, with any approach to justice to the subject.

THE WM. M. PIERSON CAMERA,

In charge of Sr. D. Cuyás and Professor CASARES;

AND THE FLOYD CAMERA,

In charge of Professor GIMENO and Sr. D. TERRADAS.

The former of these has a Dallmeyer quadruplet objective, aperture 6 inches and focal length 33 inches. The latter has a Clark objective, 5 inches aperture and 67 inches focus. Both cameras were mounted on a clock-driven polar axis, which also carried two spectrographs, to be described later.

Seven exposures were made with each camera, the exposures with the two instruments beginning and ending at the same instants to avoid jarring. They were as follows, on Seed plates No. 27:—

These negatives have recorded the longer coronal streamers out to a distance of about two solar diameters from the limb of the Sun. They likewise were not injured by the clouds, and they will be very valuable in a study of the middle and outer coronal forms. The attempted reproduction of one of the Floyd negatives shows only the general features of the corona, and fails completely to reproduce any of the exquisite detail of the original.

THE INTRAMERCURIAL-PLANET CAMERAS.

In charge of Mr. PERRINE, assisted by Messrs. GREVE, IBAÑEZ, HERNANDEZ, and HERREROS.

The search for an intramercurial planet was to be carried on with lenses exactly similar to those used at the Labrador and Egypt stations and to those used in Sumatra in 1901: 3 inches aperture and II feet 4 inches focus, constructed by ALVAN CLARK & SONS. The region to be photographed comprised an area 29° long, in the direction of the Sun's equator, by 94° wide. The Sun was in the center of this region. Four cameras were fastened together rigidly and mounted on a clock-driven polar axis so as to cover the entire region, using plates 18 X 22 inches in size. Two sets of exposures as long as possible furnished duplicate plates for the detection of defects.

The programme was carried through at the time of the eclipse as planned. The clouds interferred to such an extent, however, that it is not believed that the photographs will add anything to the results obtained at the Sumatra eclipse. The negatives have not yet been closely examined.

The intramercurial apparatus is shown, in the illustration of the camp, to the right of the 40-foot camera, though on a small scale. The corresponding apparatus of the Labrador expedition is shown, on a larger scale, in these Publications (No. 105, p. 180), and that of the Egyptian expedition in the present number (p. 37). The three mountings were designed by Mr. PERRINE and constructed under his immediate superintendence. They were very rigid and worked well.

OBJECTIVE-PRISM SPECTROGRAPH WITH STATIONARY PLATES. In charge of Professor HARTMANN.

The purpose of this instrument was to secure a series of photographs of the changing spectrum of the Sun's edge at