| RefNo | HSF/2/1/83 |
| Previous numbers | 32.8.68 and 32.8.76 |
| Level | Item |
| Title | Incomplete letter from [John Herschel], Bangalore [Bengaluru], to [Sir John Frederick William Herschel] |
| Creator | Herschel; John (1837-1921); British army officer and astronomer |
| Date | 16 April 1868 |
| Description | Commencing with a copy letter to Major [James Francis] Tennant on local climates, with theory pointing to plain country as the most cloudless [for astronomical observations of the total eclipse]. The places and country around Kolar seem to be most free from rain. It is difficult to say what plan of observation to pursue, noting the possible use of the spectroscope and the knowledge required for totality. He discusses prominences and the photosphere as targets.
The letter continues [directly to J F W Herschel] that since writing this, John has heard that the weather in the far East is prohibitory and Tennant will have to come further West, or risk it. Since he last wrote, John has become better acquainted with the subject of compensated bars and he is cross with previous computers. Reductions have been so formularized as to almost intentionally mask the truth at intermediate stages. No law of variation has been formulated or taken account of in temperature effects on the bars. It might have been arrived at some time ago if the calculations had been assayed differently and he gives a sketch of curves showing metal bar temperature lagging behind air termperature. He continues to describe the relationship between metal bars and external temperature, but the ensuing difficulty has been shirked. He discusses compensated bars and simple ones, considering how to ensure equality of temperature, which is a puzzle, he thinks. This is an old story - he cannot leave the problem well alone, but he thinks it would be a neglect of duty to pass over something compromising accuracy. |
| Extent | 6p. |
| Format | Manuscript |
| PhysicalDescription | Ink on paper |
| AccessStatus | Open |
Fellows associated with this archive
| Code | PersonName | Dates |
| NA7955 | Herschel; John (1837 - 1921); Colonel; military engineer, surveyor and astronomer | 1837 - 1921 |