
observed unequal size of the two sides. Were the light stationary, then the greatest & least lengths and brightnesses should occur at the same time in successive years; because on arrearing again at the same points of its orbit, the earth should see again the same parts of the Zodiacal light pointing to the same direction in space; but as already stated the contrary to this has been observed. The greatest elongation observed was 79[degree], & the least 50[degree], but from the varying circumstances & positions in which the observations were made, the short period of time over which they extend, and the distance of the place from the equator, to= =gether with the small number of opportunities which these conditions afforded, no numerical results of much accuracy can be derived from them alone; but some advantage may be gained by comparing them with the results of former observers. The number, however, of these i.e., of actual observers, is comparatively small, and they are all very recent; for strange to say, no notice of the Zodiacal Light is found amongst the writings of astronomers, or natural philosophers until 1661. and indeed when we consider that this phenomenon may be described as a lenticular shaped light seen in the Western sky after sunset, and in the Eastern before sunrise, with a length of about 60[degree], a breadth of 20[degree], combining with a bright= =ness nearly equal to that of the Milky Way, a regular mathematical figure which makes it far more remarkable, & rising at a greater angle to the horizon, so as to be better seen in countries nearer the equator than ourselves, and being probably of as great antiquity as the sun itself, - truly it is astonishing that all these notabilia should have been passed over in the earlier ages of the world, when civilization flourished more to the South, and the men of ancient Athens and Babylon lived under a clear sky, in a genial climate, which invited, rather than forbade, the contemplation of the firma= =ment by night. It remained however for the inhabitants of these cloud-vexed Northern islands, to be the first to take notice of the
Please login to transcribe
Manuscript details
- Author
- Charles Piazzi Smyth
- Reference
- AP/30/18
- Series
- AP
- Date
- 1840
- IIIF
-
(What's this?)This is a link to the IIIF web URL for this item. You can drag and drop the IIIF image link into other compatible viewers
Cite as
Attempt to apply instrumental measurement to the Zodiacal Light , 1840. From The Royal Society, AP/30/18
Comments