But the crimes I am charged with are, that on the 7th of August last, some person or persons did, accidentally or maliciously, disturb the telescope, during the exposure of plates Nos. III. and IV., and that the said plates mislead, and are not faithful representations of the phenomena seen and also, that they contradict the statements of Commander Ashe, with regard to the “rapid shooting out of a certain prominence.”
In clearing myself of these heavy charges, I shall divide my evidence into two parts—negative and positive.
In the first place, the telescope was firmly placed upon a platform made by the heavy sleepers borrowed from the railway station, and surrounded by boards, as may be seen in the photograms; and Commander Ashe has been too long at sea to travel 1398 miles with a heavy telescope, and then not to be able to give it stability. There were four persons inside the building—Mr. Falconer, seated some distance from the telescope, observing the general appearance of the eclipse with the naked eye; Mr. Stanton upon a platform, ready to uncover and cover the object-glass with a light cloth; Mr. Douglas in the dark room, and myself at the telescope, which was firmly clamped in hour-angle, and declination. The people outside were at a distance upon an elevation, and were quite still. The telescope, if it moved, must have moved in hour-angle, or declination, or in both; if it moved in hour-angle, the endless screw must have tripped upon the driving-wheel, which it could not do without making a noise, which would have been heard by me. If it moved in declination, Mr. Stanton must have moved it in uncovering the object-glass; but in so doing, he must have given the telescope a pretty hard blow, of which he must have been aware. But neither Mr. Stanton nor myself are aware of any disturbance of the telescope. There was no wind, which would only have caused a vibration, and given a blurred image. In examining Nos. I. and II. photograms, the limb of the moon may be clearly traced, and there is not a shadow of suspicion of any relative motion in the telescope. Here we have proof that the driving clock was performing its duty well for the first half of totality; and no one will have the hardihood to say that it altered its rate in the next minute and a-half. In looking at No. IV. photogram, we see that a point of light is double. Now, we will suppose this duplication was caused by the telescope receiving a smart blow; then, by drawing a line through the two positions of the same object, we get the direction of the motion. Now, look to the right and we see a protuberance with a triplicate form. Here, then, the telescope must have received two blows; and by drawing a line along the top of the three figures, we get the direction of the motion, or disturbance; and on looking at the different directions of the two motions, we see that the telescope moved two ways at once, and also, that one part of the plate was disturbed once, whilst another part of the same plate was disturbed twice—which is absurd; and lastly, Mr. Vail who had not seen the photograms when he wrote his report, gives a description of certain lines and cracks that are to be seen in the negatives when they are examined by a lens. How is it possible to get over this? Here, an American gentleman sees with a telescope exactly what is photographed. But this is negative testimony; I will now prove, conclusively, giving geometrical evidence, that Mr. De la Rue has made an egregious misstatement. The reader will have it in his power to corroborate this testimony. Place a piece of paper behind the photograms III. and IV. (taken in the principal focus), and with a needle make holes in four or five different places, taking care not to mark the bottom of a protuberance, which is a notch, but where you can see distinctly the limb of the moon; then remove the paper and find the centre of three holes, and draw a circle through them; and if it passes over the other holes, you have positive proof that the centre did not move during the exposure. Now, look at the lithograph, and you will see a circle drawn through five marks made upon the limb of the moon of No. III., and through four marks made upon the limb of the moon of No. IV.—Q. E. D.
IV.
Having proved that the very remarkable photograms taken at Jefferson are correct representations of the phenomena seen at that place, I will proceed to describe the details of the four negatives that are to be seen when examined with a lens.
The moment the sun disappeared, out flashed the corona, which resembled an aurora, and no doubt belongs to the sun, and not to the moon. No. I. shews the continuous mass of red matter with the flame-like appearance of the so-called “Ear of corn;” a little to the left are seen two detached red lumps, like glowing coals; and underneath is seen the slightest trace of a prominence that is to play a conspicuous part in the eclipse. No. II., the limb of the moon, is seen completely round, and a little more is seen of the prominence underneath. Now, it is time to remark that the flame-like mass in No. I., and the detached prominences in Nos. I. and II., appear to cut in upon the limb of the moon. Dr. Curtis, after trying several experiments, is firmly convinced that this appearance is entirely due to a photographic effect, by excessive overexposure of the plates. I have to remark, that nothing was more conspicuous than the indentations of the glowing masses upon the limb of the moon. Remember that these protuberances were not dazzling lights, but could be contemplated with the greatest comfort; and the eye is so fastidious, that in running round the limb of the moon, it immediately detects the sudden break in the circumference. But I have a theory, and it is dangerous to trust the eye of a man with a theory, without good support. Directly after the eclipse, some of those outside joined us, and the conversation was upon the extraordinary shooting-out of the prominence, which they were all describing. In the midst of the conversation, a carpenter touched me on the arm, and said: “But what were the notches on the moon?” Now, this is conclusive evidence, and would be taken in any court of law. Remember, the word “notches,” (the language of a carpenter) is his own, and no other word do I think so applicable. I answered that I did not know, and that nothing puzzled me more. On examining the negatives with a lens, I saw the limb of the moon distinctly through the prominence; and further, that the part on the moon was a similar and inverted figure to the upper part, and I was convinced that the “notch” was caused by reflection of the protuberance on the surface of the moon.
Let B F be the height of the protuberance, and L B the line of sight, tangent to the point B, and let the lines of sight, both direct and reflected, be considered parallel to each other; now, through the point D draw a tangent, and let the incident ray, F D, and the reflected ray, O D, make equal angles with it; then, the exterior angle, O D C, is equal to the angles D AC and A C D; take away the right angles, D and A, and we have the remaining angles, O D E and C, equal; and B A (the depth of the notch) is equal to the versine of the angle of reflection.