Sowerby retained the specimens used in the expansive volumes he helped to produce. Many notable geologists, and other scientists of the day were to lend or donate specimens to his collection. He had intended that his some thousands of minerals, many not known elsewhere, a great variety of fossils, most of the plants of English Botany about 500 preserved specimens or models of fungi, quadrupeds, birds, insects, &c. all the natural production of Great Britain become the foundation of a museum. The addition of a room at the rear of his residence, housing this collection, was to see visits from the president of the Royal Society, Joseph Banks, and Charles Francis Greville who also lent to the informal institution. A much sought exhibit, one that was frequently chipped for samples, was the Yorkshire meteorite; this was sighted and collected in 1795, the first recorded English meteorite.