Letter, from Henry Oldenburg to Renatus Franciscus Slusius Sends an algebraic proposition (see EL/O1/46a) for Slusius's consideration which some say had already been solved by Johann Rahn in his 'Algebra'; Oldenburg will send a copy of the 'History' of the Royal Society as soon as it is printed; wishes for any titles of books on physics or mathematics published in Liege At the end Oldenburg has written a note for Henry Justel about whether it was Magnan who wrote against Lalovera's tract on mechanics 6 June 1667