The sunspot observations by Samuel Heinrich Schwabe
  A long time-series of sunspot observations is preserved from Samuel Heinrich Schwabe who made notes and drawings of sunspots from 1825-1867. Schwabe's observing records are preserved in the manuscript archives of the Royal Astronomical Society, London. The drawings have now been digitized for future measurements of sunspot positions and sizes. The present work gives an inventory and evaluation of the images obtained from the log books of Schwabe. The total number of full-disk drawings of the sun with spots is 8486, the number of additional verbal reports on sunspots is 3699. There are also 31 reports about possible aurorae. 
R. Arlt
physics.hist-ph astro-ph.SR