On the second picture the details of the polar rays are better brought out, but the extensions are shortened. In the third the region near the sun’s edge has many interesting details very clearly defined, while all the extensions are gone. It is evident that each lens has its advantage, according to the details sought, and they ought all to be employed in the eclipse. The reproductions on paper by no means do justice to the original negatives, which make the distinctions even more pronounced than shown on Chart V. [Illustration: CHART V.--RELATIVE IMAGES OF THE CORONA AS TAKEN WITH TELESCOPES RANGING FROM FORTY FEET TO FOUR FEET IN FOCAL LENGTH.] Some amateur observers have telescopes but no mountings suitable for eclipse work, and many astronomical telescopes have good equatorial mountings at home which are yet unavailable in the field for lack of proper foundations and supports. The ordinary telescope balanced near the center, with the eye end subject to all sorts of motions which may happen through jarring and rough handling in the hurry of shifting photographic plates, makes a very poor eclipse apparatus. All telescopes of any length should be held firmly at each end, so as to be perfectly steady, since the least vibration ruins a coronal picture devoted to delicate photographic effects. There are two ways of accomplishing this, and only two. Dispensing with an equatorial mounting, the lens must be set permanently on a base, and light reflected from a mirror must be utilized, which shall be concentrated on a plate also placed on a fixed base. This is the method employed by Schaeberle in Chili, April 16, 1893, to obtain No. III of Chart V. There is no objection to it if an observer possesses a perfectly plane mirror, which it is very difficult and also expensive to obtain; if the reflecting mirror should be imperfect it would distort the image of the corona. The second method, lacking a good mirror, is to mount the long-focus lens in a tube and point it directly at the sun. A forty-foot lens was thus mounted at Cape Ledo for December 22, 1889, and its action was very satisfactory. Of course, it was a cumbersome arrangement, and could not be employed by a small party. The foundation for the mounting of the forty-foot tube consisted of two casks filled with stones and cement, and set firmly in the ground. These made two good piers, since the narrowing tops of the casks held the bed plates of the telescope as in a vise. A triangle, whose base was parallel to the earth’s axis and having the telescope tube itself for the long side, was fitted with an extension rod for adjustment in altitude on the third side, and the whole was made to revolve on ball bearings. This triangular support was rotated by a side rod of adjustable length, whose end terminated in a sand piston working with a regulating valve. The sand flowed out steadily like an hour-glass, and dropped the tube, keeping it central on the sun. The image was