| RefNo | HSF/2/1/96 |
| Previous numbers | 32.8.80 |
| Level | Item |
| Title | Letter from J [John] Herschel, Bangalore [Bengaluru], to 'Dear Pater' [Sir John Frederick William Herschel] |
| Creator | Herschel; John (1837-1921); British army officer and astronomer |
| Date | 27 May 1869 |
| Description | He sends a few words of reply to his father's enclosure in Bella's [Isabella Herschel's] letter. He finds that he has more copies of Nos. 102, 103 and 105 than he is likely to distribute and notes his receipt of other Royal Astronomical Society notices, but none of no.109. He would be glad to save his father trouble and he discusses other printings and their distribution, referencing his last solar spectrum letter to [William] Huggins. He has been devoting his every available minute to this last topic using the 4-inch hand spectroscopes sent out by the Royal Society and he notes his plans to observe a large area adjoining the Sun's circumference, which is the proper direction for research he thinks. He discusses the dispersion of light and he is sanguine of success, if he can adapt compound prisms to the existing instrument. He gives his ideas on achromatic lenses, and substituting a simple lens for a compound one. He has tested his plan by putting three of the prisms in line in front of the slit, 'dispersing considerably before the rays from the object glass had conversged to their focus'. He notes that the result was puzzling, but beautiful in the explanation. He gives an explanation, with a sketch, concluding that one result which might be seen would be red, blue and yellow lines being visible at the same time. The Argus Nebula must be given to the Melbourne Telescope for elucidation, as he is too late for it and clouds obscure the low South. John is hard at work reducing the baseline observations. Parchment documents were inserted into the terminal marks, when closed, containing some facts, including and approximate length provided by John. He will now spend months, with an assistant, confirming the first decimal and then supplying a second. He gives details of the work, and says that his writing table is now 'swarming with huge black ants'. |
| Extent | 8p. |
| Format | Manuscript |
| PhysicalDescription | Ink on paper |
| AccessStatus | Open |
Fellows associated with this archive
| Code | PersonName | Dates |
| NA7955 | Herschel; John (1837 - 1921) | 1837 - 1921 |