Length Of Trail Research Articles

IN the hope of being able to record photographically the passage through our atmosphere of some of the August meteors, I exposed during the night of August 12 three photographic plates, one towards the pole star, and the other two towards the constellations of Perseus and Lyra. On the plate exposed to the latter constellation absolutely no trace of any meteor trail can be seen, but on the other two a very definite and distinct trail, peculiar for the different degrees of condensation in it, is easily visible. From the position and similarity of the trail on the two plates, there is no doubt that the same meteor was in question. These two plates were exposed in cameras, one a 5 × 4 with a Zeiss double combination lens of 224 millimetres focal length, and the other a 71/2 × 5 with a Dallmeyer rapid rectilinear lens. The trail recorded by the latter instrument falls so near the edge of the plate that the image is somewhat out of focus; but on the other plate, although it is also near the edge, the image is very sharp and clear. From an examination of this plate, the following particulars have been obtained:—The path of the meteor extends nearly 9° in the constellation of Camelopardus, and a comparison with Cottam's star chart shows that the coordinates of the points of appearance and disappearance were, according to the photographic plate, R.A. 4h. 53m. Decl. + 65° 25′, and R.A. 5h. 32m. Decl. + 66° 15′. The actual visible length of trail must have been much longer than this, although the lens and plates used were both very rapid. It may be mentioned that the most dense part of the trail was equal in intensity to that given by the image of β Camelopardus (4th mag.) after an exposure of fifty-five minutes (11.20 p.m. to 12.15 a.m.).