For example, the German-born physician Engelbert Kaempfer (1651–1716) spent two years in Japan (1690–1692) with the Dutch East India Company, conducted extensive studies on local plants, and returned with botanical samples, materials relating to acupuncture and the country's political, social and physical condition. After Kaempfer's death Sloane bought the lot. One item was a manuscript History of Japan, translated into English at Sloane's expense by his librarian John Gaspar Scheuchzer and published in two volumes in 1727.
Although the original manuscript was in German, the printed German version was a translation from the English edition. Sloane also subscribed to plant hunting expeditions. Other specimens and documents were contributed directly or indirectly by an array of individuals, friends and acquaintances including William Dampier.
Sloane bought the property next door to his house, to house the ever-expanding museum, which became a prime destination for visiting connoisseurs and scientists.
When declining health forced Sloane to retire from his medical practice in 1742, he transferred the collections, along with the rest of his household, to the Manor House in Chelsea.
Sloane's carefully drafted will, initially drawn up in October 1739 and reinforced by half a dozen codicils between 1746 and 1752, directed his executors to offer the collection for sale, and stipulated that the purchaser should provide a legacy of £20,000 for Sloane's two daughters.