A little ramble through 19th century astronomy - Mars observed in 1865

The Planet Mars

During the oppositions of 1862 and1864, we have made upwards of 100 drawings of the planet Mars, on object of so much interest, from the changing phases of its very Earth-like surface; and we trust that a selection from them arranged so as to render a comparison of both series at once easy and obvious. The recurrence of the markings in each series tends to the conclusion of their general permanence, modified nethertheless apparently, by the difference of position of the planet’s axis by atmospheric causes on its surface, as is very observable in Nos. 1 and 6 of Mr Banks’ 1862 set, which differ but a few minutes in Martial time.

Drawings by Mr Banks

Each series shows the most interesting phases at intervals during one rotation, and the Nos of 1862 and 1864, synchronise respectively as far as practicable; but the exhibition of remarkable features has been deemed of mire consequence than a rigid adherence to differences in time. There is consequently, a greater interval between the first than the last three of each set.

The dark markings are usually supposed to be analogous to our seas; but we suggest, for further consideration, whether when near the centre of he disc, they exhibit the characteristic reflection n of a fluid surface under a vertical sun? The southern “snow zone”, so conspicuous in 1862, was much less striking during the last opposition, but the northern polar regions, which has since come into view, appeared to have much diffused light about it, terminated in some views, by luminous points, connected by a serrated outline. This is most decidedly seen in Mr Green, No 4, 1864, where, from irradiation, it sensibly impaired the true figure of the disc.

Drawings by Mr Green

The drawings from which the accompanying series have been carefully reduced were, as already stated , made independently by Mr Banks at Ealing and Mr Green at St John’s Wood; and they venture, from their professional familiarity with the pencil, to claim for them the truthfulness which is acquired by practice in rendering upon paper the impressions made upon the eye whilst their fidelity to the originals has been secured by Mr Green lithographing them himself.

The instruments employed were by Mr Banks, a Tulley of 3.75 inch aperture and 63 inch focal length; by Mr Green a French object glass of fine quality, 4.25 inch aperture and 58-inch focus. The powers used were from 160 to 240; less than the former being insufficient to bring out the details; and a very few fine nights only allowing the use of the latter. Mr Banks found a Kitchener’s Pancratic Tube, drawn out to 160, of much easier and sharper definition when observing the “half tint markings” than a Huygenian 180, with which the bright points were generally best seen.

In conclusion, we trust that this effort to excite in others the interest we ourselves have felt will be kindly received by other amateurs, and tend to  draw their attention to the planet during the next opposition in January 1867, when, as far at least as increased diameter is concerned, the opportunity for observation will be somewhat more favourable than during that now passed.

W L Banks, Ealing

N E Green St John’s Wood

February 14^th 1865

 

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