On reverse: Newton's sketch of a microscope.||Printed in NC, 4: 536-7, where it is dated April/May 1709 and described as probably to Allardes, and again (without any comment or cross-reference) in NC, 5: 371-3 as 28 January 1713 and to Scott. The latter is clearly correct, as appears from Scott's reply [MINT00453 (Mint 19/1/188)], which supplies the date of this letter. Rough draft in Cambridge University Library Additional Ms. 3965(12), f.362r.||Wastage in copper is higher in Scotland than England due to the fiercer heat of the coal furnaces. For this reason, the Scots were allowed to resume their old practice of adding copper during melting, though no such allowance is made in England [see notes to MINT00387 (Mint 19/1/183)]. Consequently, the waste in Scotland should be proportionately diminished in other respects.