In 1793 Lord Macartney arrived in China as ambassador of King George III. The aims of his embassy were largely directed towards the enlargement of British trade with the far east, and especially with China. The embassy also had a diplomatic and cultural mission, to impress the Chinese with British achievements. They were to do so largely by distributing presents of British manufactures, chief among them being scientific instruments. The Chinese refused the embassy's requests, and clearly regarded the gifts of instruments as merely ingenious toys. This paper describes the role of instruments in the embassy, and contrasts British expectations with Chinese attitudes to scientific instruments. The embassy's failure is shown to reveal fundamental differences in British and Chinese eighteenth-century responses to science, and has wide cultural implications.