1. Spectroscopes

Various memoranda concerning spectroscopes, 1901-1925.

1. 'Spectroscope', 21 September 1901.
2. 'Spectroscope', 23 September 1901.
3. 'Photographic Spectroscope', January 1900.
4. 'Photographic Spectroscope', 14 October 1901.
5. 'Christie's direct-vision "half prism" spectroscope'.
6. 'Wave lengths of spectrum lines'.
7. 'Standard Wavelengths', 1922 (printed).
8. 'Report on Pure Carbon Electrodes', 1925.

2. Photoheliographs

Correspondence and memoranda concerning photoheliographs, 1908-1926, including:

1. 'Relative definition of the Greenwich Photoheliographs'.
2. 'Madras Photoheliograph now at Kodai Kanal Observatory'.
3. 'The Thompson Photoheliograph, Alteration of scale'.
4. 'The Dallmeyer Photoheliograph', 1910.
5. Correspondence with Ross and Co. on adaptors for homocentric lenses.
6. 'Dallmeyer Photoheliograph', 1911.
7. 'Abney Lens'.
8. 'Dallmeyer Lens'.

Correspondence with Sir Howard Grubb concerning a new 4" object glass for the Dallmeyer Photoheliograph, 1911-1912.

3. Time Ball

Notes of days during the period 1895-1909 when the Time Ball could not be raised or dropped due to faults in the mechanism or the weather. There is also correspondence, principally with Troughton and Simms, concerning repairs to the Time Ball.

4. Clocks

List of clocks and chronometers in the possession of the Royal Observatory on 1 January 1909, and where they were placed.

Report, including graphs, on the temperature of the clock room, giving results and comparisons for 3 and 6 month periods, 1911-1912.

Memoranda concerning clocks, including the Krille chronograph and receiving instruments, 1912-1916.

Blueprint (No. 3697M) of the micrometer for the transit instrument, 27 August 1920.