[draft]
Warren de la RueL.
8 Oct 57
Dr Sir
I am extrly obl t y for ye vy beautif. phot of ye moon <1> wch y sent me & wch I look upon as ye precursor of still more importt results. I am afraid that I am not able to offer any suggestions that wd be useful t y. My instant. process a full acct of wch was publ in th Comptes Rendus is not applicable,<2> except to terrestl objts it consists in illumg ye objects wth a flash of electrical light- When common light is used, the process altho’ sensve is not more so than the collodn process-
The first image wch you obtained in the focus of ye telescope, in a given time, has only necessarily only a given certn degree of lightness. But it appears to me that nothing prevents your obtaining a tenfold degree of lightness in the magnified image, simple by giving allowing time enough, and I think the resulting effect wd be very much finer. Dr Diamond of the Lunc Asyl. twickenm used to be vy skilful in obtaining a fine silvery effect on glass-<1>
I think that an improved effect might be obtain’d with Jupiter (and even with the lunar crust) by interposing a concave lens before the rays reach the focus of the telescope, so as to lengthen the focus a little and obtain a larger image, perhaps twice the diamr of the original image. This wd make the delinn of the belts on the planet much clearer, &an image wdbe obtained I think in ½ a minute.
Ld Rosse took a great interest in these astronoml What has already been accomplished is of so much scientific interest that we must that I trust ye subject will be presented that I hope y will find leisure to continue such beautful expts.
[expanded version:]
Warren De La Rue
Lacock Abbey
8 October 1857
Dear Sir,
I am extremely obliged to you for the very beautiful photographs of the moon which you sent me and which I look upon as the precursor of still more important results. I am afraid that I am not able to offer any suggestions that would be useful to you. My instantaneous process a full account of which was published in the Comptes Rendus is not applicable, except to terrestrial objects it consists in illuminating the objects with a flash of electrical light. When common light is used, the process although sensitive, is not more so than the collodion process.
The first image which you obtained in the focus of the telescope, in a given time, has only necessarily only a given certain degree of lightness. But it appears to me that nothing prevents your obtaining a tenfold degree of lightness in the magnified image, simply by giving allowing time enough, and I think the resulting effect would be very much finer. Dr. Diamond of the Lunatic Asylum Twickenham used to be very skilful in obtaining a fine silvery effect on glass.
I think that an improved effect might be obtained with Jupiter (and even with the lunar crust) by interposing a concave lens before the rays reach the focus of the telescope, so as to lengthen the focus a little and obtain a larger image, perhaps twice the diameter of the original image. This would make the delineation of the belts on the planet much clearer, and an image would be obtained I think in ½ a minute.
Ld Rosse took a great interest in these astronomical What has already been accomplished is of so much scientific interest that we must that I trust the subject will be presented that I hope you will find leisure to continue such beautiful experiments.
Notes:
1. Primarily known as a member of the family of stationers who introduced the envelope to correspondence, Delarue was an accomplished scientist who invented a technically practical but economically unfeasbile lightbulb in 1840. A decade later, influenced by James Nasmyth, he built a 13 inch telescope and used it to make drawings of celestial objects. A daguerreotype of the moon shown at the Great Exhibition in 1851 inspired him. His subsequent photographs of the moon, taken by the wet collodion process, remained the standards until the mid-1860s.
2. The Amphitype process - see Doc. No: 06493.
3. Dr Hugh Welch Diamond (1809-1886), surgeon & photographer.