 Subsequently they made another, larger, better piece of apparatus, and taking particular care that the measurements should be accurate, tested the hypothesis “that supposes the pressures and expansions to be in reciprocal proportion.” The results are set out, with misprints, in two tables, and Boyle’s conclusion was that the experimental findings matched the predicted results very well in the case of compression, less well in the case of rarefaction. Boyle suggested that the divergence from the expected result in the case of rarefaction may have been due to “some little aerial bubbles in the quicksilver” (“so easy is it in such nice experiments to miss of exactness,” he added).