Letter, from William Balle to Henry Oldenburg, dated at Mamhead, Devon Autograph letter with observations of Saturn and of Mars There is a figure of Saturn as it was seen at 4 am with a 12 foot glass Balle has also attached a paper model of Saturn as it was seen in Mamhead, Devon with a telescope 38 foot approximately and a double eyeglass A copy of Balle's accounts for expenditure on magnets is attached 14 April 1666