TALBOT7464

[draft]

Warren de la Rue

L.
8 Oct 57

D^r Sir

I am extr^ly obl t y for ye vy beautif. phot of ye moon ¹ w^ch y sent me & w^ch I look upon as ye precursor of still more import^t results. I am afraid that I am not able to offer any suggest^ions that w^d be useful t y. My instant. process a full acc^t of w^ch was publ in th Comptes Rendus is not applicable,² except to terrest^l objts it consists in illum^g ye objects w^th a flash of electrical light- When common light is used, the process altho’ sens^ve 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 w^d be very much finer. D^r Diamond of the Lun^c Asyl. twicken^m used to be v^y skilful in obtaining a fine silvery effect on glass-³

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 diam^r of the original image. This w^d make the delinⁿ of the belts on the planet much clearer, &an image w^dbe obtained I think in ½ a minute.

L^d Rosse took a great interest in these astronom^l 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 beaut^ful exp^ts.

[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.

L^d 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.